Portable electronic device having a radio transmit-receive unit and a computer unit

Abstract: A radio transmit-receive unit can perform the communication processing stably without being affected by high frequency noise with the system activation of a computer unit, whereby if a communication processing request from the radio transmit-receive unit occurs, the computer unit sets the system state of a sub-CPU being activated to a rest state, a counter starts clocking the signal receive time of the radio transmit-receive unit when the system state of the sub-CPU is in a rest state, and a latch circuit holds electric field strength information of carrier received by the radio transmit-receive unit upon the termination of clocking by the counter. And the computer unit switches the system state of the sub-CPU being at rest to an active state, based on the end state of clocking by the counter, to restart the activation of the computer unit.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a portable electronic device having a computer unit for performing data processing of desired information with radio communication. Related Background Art Conventionally, this type of electronic device has a radio transmit-receive unit for performing the radio communication and a computer unit for performing the data processing, wherein such a protective measure is often taken that the radio transmit-receive unit is encased for protection in a box with a metallic plate or the like to lie in a shield state, providing a greater interval between computer unit and antenna, or the computer unit is encased in a box with a metallic plate or the like for shielding, so that the influence of high frequency noise from the computer unit may be eliminated while the radio transmit-receive unit is processing the communication. However, in a portable electronic device requiring the miniaturization, as it is an antinomy proposition that the device is miniaturized while the computer unit is completely shielded, the computer unit may be arranged as great distance as possible away from the antenna, in which there was a problem that the influence of high frequency noise from the computer unit was not completely removed. In REVIEW OF THE ELECTRICAL COMMUNICATIONS LABORATORIES, Vol. 35, No. 2, March 1987, Tokyo, pages 109-114, by Yuki et al, an electronic device is described comprising a radio transmit-receive unit, a computer unit (logic section) and a control means for setting the computer unit to a rest state, i.e. a CPU halt mode. Moreover, an intermittent reception is described, during which a power supply is turned off. The rest state and intermittent reception are established for power saving purposes. Furthermore, the EP-A-0 463 621 discloses an electronic device as defined in the preamble of claim 1. The computer unit is separated into a receiving unit used for selectively storing data in a memory, and an evaluation unit for evaluating the stored data. Thereby, any interference resulting from data processing can be reduced during reception. Furthermore, a timer is arranged to provide a timing reference for switching the receiving unit and the evaluating unit. In particular, the evaluation unit is switched on and off at particular timings determined by the timer. Thus, noise is reduced by separating data reception and data evaluation in order to minimize interference caused by data processing. It is an object of the present invention to provide an electronic device having a radio transmit-receive unit by means of which noise can be minimized during reception. This object is achieved by an electronic device as defined in claim 1. Advantageous developments of the invention are defined in the dependent claims. In the present invention, if a communication processing request from the radio transmit-receive unit occurs, control means sets the system state of the computer means being activated to a rest state, timer means starts clocking the signal receive time of radio transmit-receive unit when the system state of the computer means is in the rest state, and holding means holds electric field strength information of carrier received by the radio transmit-receive unit upon the termination of clocking by the timer means. And the control means switches the system state of the computer means being at rest to an active state based on the end state of clocking by the timer means in order to restart the activation of the computer means, whereby the radio transmit-receive unit can perform the communication processing stably, without being affected by high frequency noise arising with the system activation of computer means. Also, the control means is configured to set the system state to a rest state by shutting down the power supply to the computer means, whereby the radio transmit-receive unit can perform the communication processing stably, without being affected by high frequency noise arising with the system activation of computer means, by stopping the occurrence of high frequency noise of computer unit temporarily. Further, the control means is configured to set the system state to a rest state by resetting the computer means, whereby the radio transmit-receive unit can perform the communication processing stably, while influence of high frequency noise arising with the system activation of the computer means is relieved by suppressing the occurrence of high frequency noise of computer means temporarily. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram for explaining a configuration of a portable electronic device according to one embodiment of the present invention. Fig. 2 is a flowchart showing one example of a first radio communication processing procedure in the portable electronic device according to the present invention. Fig. 3 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 2. Fig. 4 is a block diagram for explaining a configuration of a portable electronic device according to another embodiment of the present invention. Fig. 5 is a flowchart showing one example of a second radio communication processing procedure in the portable electronic device according to the present invention. Fig. 6 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 5. Fig. 7 is a block diagram for explaining a configuration of a portable electronic device according to another embodiment of the present invention. Fig. 8 is a flowchart showing one example of a first radio communication processing means in the portable electronic device according to the present invention. Fig. 9 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 8. Fig. 10 is a block diagram for explaining a configuration of a portable electronic device according to another embodiment of the present invention. Fig. 11 is a flowchart showing one example of a second radio communication processing means in the portable electronic device according to the present invention. Fig. 12 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 11. Fig. 13 is a flowchart showing in detail another example of a carrier sense processing procedure as shown in Fig. 8. Fig. 14 is a flowchart showing in detail still another example of a carrier sense processing procedure as shown in Fig. 8. Fig. 15 is a block diagram for explaining a configuration of a portable electronic device according to another embodiment of the present invention. Fig. 16 is a flowchart showing one example of a first radio communication processing means in the portable electronic device according to the present invention. Fig. 17 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 16. Fig. 18 is a block diagram for explaining a configuration of a portable electronic device according to another embodiment of the present invention. Fig. 19 is a flowchart showing one example of a second radio communication processing means in the portable electronic device according to the present invention. Fig. 20 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 19. Fig. 21 is a flowchart showing in detail another example of a carrier sense processing procedure as shown in Fig. 16. Fig. 22 is a flowchart showing in detail another example of a carrier sense processing procedure as shown in Fig. 16. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig. 1 is a block diagram for explaining a configuration of a portable electronic device according to one embodiment of the present invention. In the figure, 1 is a computer unit, comprising a keyboard for the input of information or instructions, a display unit for displaying input information or processed result, a memory for storing data and processing procedures as shown in flowcharts as thereafter described, processing means for processing data in accordance with processing procedure stored in the memory, and communication interface for communicating the information processed by processing procedure to the outside. The computer unit 1 is connected to a sub-CPU 2 via a control line 8, the sub-CPU 2 comprising a memory for storing data and programs for executing processing procedures as shown in flowcharts as thereafter described, processing means for processing data in accordance with the program stored in the memory, and a communication interface for communicating the information processed by processing means to the outside. The sub-CPU 2 communicates with the computer unit 1 for the transmission of information. The computer unit 1 is initiated upon a clock supplied from an oscillation circuit 14 via a clock line 12 with a reset signal 7 released. The clock supplied via the clock line 12 from the oscillation circuit 14 is divided in frequency by a divider circuit 15, and an output 13 after dividing into a frequency of e.g., 2msec is output via a low-pass filter 19 to a counter 16. 3 is a radio transmit-receive unit for communicating with an external equipment, not shown, via an antenna 4. A received electric field strength detected by the radio transmit-receive unit 3 is A/D converted by an A/D converter 18, and then latched in a latch circuit 17 via an A/D converter output line 25. The latch circuit 17 may be either of a first-in first-out system of memory and an addressing system, when storing the received electric field strength for a plurality of channels. 5 is a battery for supplying power supply voltage in accordance with the on/off state of a power supply switch 11. 6 is a power supply monitor IC for monitoring the power supply voltage state from the battery 5 to send out a reset signal via a computer reset line 7 to the computer unit 1 and an AND gate 24. The AND gate 24 sends out the reset signal via a sub-CPU reset line 10 to the sub-CPU 2, based on the reset signal and the output state from the computer unit 1. 20 is a ripple carry-out of the counter 16, 21 is a signal strength detection line, and 22 is a latch data output line for outputting electric field strength data latched in the latch circuit 17 to the sub-CPU 2. 23 is a reset line for transferring a counter control signal from the computer unit 1 to the counter 16. 9 is a control line. In the portable electronic device thus constituted, if a communication processing request from the radio transmit-receive unit 3 occurs, control means sets the system state of the computer means being activated to a rest state, timer means (counter 16) starts clocking the signal receive time of the radio transmit-receive unit 3 when the system state of a computer means (sub-CPU 2) is in a rest state, and holding means (latch circuit 17) holds electric field strength information of carrier which the radio transmit-receive unit 3 has received upon the termination of clocking by the timer means (counter 16). And the control means (computer unit 1) switches the system state of the computer means (sub-CPU 2) being at rest to an active state, based on the end state of clocking by the timer means (counter 16), to restart the activation of the computer means (sub-CPU 2), whereby the radio transmit-receive unit 3 can perform the communication processing stably, without being affected by high frequency noise arising with the system activation of the computer means (sub-CPU 2 in this embodiment). Also, the control means is configured to set the system state to a rest state by shutting down the power supply to the computer means, whereby the radio transmit-receive unit 3 can perform the communication processing stably, without being affected by high frequency noise arising with the system activation of the computer means, by stopping the occurrence of high frequency noise of the computer means temporarily. Further, the control means is configured to set the system state to a rest state by resetting the computer means, whereby the radio transmit-receive unit 3 can perform the communication processing stably, while the influence of high frequency noise arising with the system activation of the computer means is relieved by suppressing the occurrence of high frequency noise of the computer means temporarily. Fig. 2 is a flowchart showing one example of a first radio transmit-receive processing procedure in a portable electronic device according to the present invention. Note that (1) to (9) indicate each step. First, if power switch 11 is turned on, computer unit 1 is reset upon a reset signal sent out via the computer unit reset line 7, and sub-CPU 2 is reset upon a reset signal sent out via the sub-CPU reset line 10 (1). Then, the computer unit 1 is checked to determine whether to start the radio communication (2), in which if the answer is NO, the computer unit 1 executes other process (3) and the procedure returns to step (2). On the other hand, if the determination at step (2) is YES, the radio transmit-receive unit 3 receives all the channels one by one to execute carrier sense process (the detail procedure will be described later) for retrieving the channel having a predetermined electric field strength or less. Then, the presence or absence of any vacant channel is determined (5), in which if the answer is NO, the computer unit 1 displays a message "NO VACANT CHANNEL COMMUNICATION UNABLE" on a display unit, not shown (6), and the procedure returns to step (2). On the other hand, if the determination at step (5) is YES, an arbitrary vacant channel, for example, a channel having the smallest channel number among the vacant channels, is selected (7). Then, communication is performed through selected channel, that is, the computer unit 1 communicates data with the sub-CPU 2, which in turn ocmmunicates data with the radio transmit-receive unit 3, with data exchange (8), and the end of data communication is judged (9), in which the procedure returns to step (2) if the answer is YES, or otherwise to step (8). Referring now to flowchart as shown in Fig. 3, processing operation of carrier sense as shown in Fig. 2 will be described below. Fig. 3 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 2. Note that (1) to (9) indicate each step. First, data for setting transmit-receive channel is set to zero (1). At this step, the radio transmit-receive unit 3 has no channel setting. Then, the computer unit 1 sets channel (N=N+1) in the radio transmit-receive unit 3 via the sub-CPU 2 (2). Then, the sub-CPU 2 is kept in reset state (3), and reset line 23 of counter 16 is released (4). Then, waiting for a predetermined time to elapse until the counter 16 outputs a ripple carry-out 20 (5), and if the ripple carry-out 20 is output, the sub-CPU 2 is released from reset state (6). Then, ripple carry-out signal 20 is output by a processing to be carried out during waiting time of the step (5), that is, if the input of the counter 16 is counted (2msec for one period) by, for example, fifteen times, and latch data latched in latch circuit 17 by a processing of latching the value of A/D converter 18 in latch circuit 17 is read by the sub-CPU 2 via the latch data output line 22, and transmitted via the control line 8 to the computer unit 1 (7). Then, the reset line 23 is kept in reset state (8). And a determination is performed as to whether or not the signal strength of each of all the channels is read (N=10 (where channel number N is e.g., from 1 to 10)) (9), in which if the answer is YES, the procedure returns to main procedure, or otherwise returns to step (2) to repeat the above processing. In the above embodiment, the radio transmit-receive unit 3 is prevented from experiencing influence of noise arising in the processing of the sub-CPU 2 by resetting the sub-CPU 2 during the communication of the radio transmit-receive unit 3, but it will be appreciated that the radio transmit-receive unit 3 may be configured not to be affected by noise arising in the data processing as above described, by shutting down the power supply to the computer unit 1 during the communication of the radio transmit-receive unit 3, as will be described later. Fig. 4 is a block diagram for explaining a configuration of a portable electronic device according to another embodiment of the present invention. In the figure, 51 is a computer unit containing RAM 81, the contents of RAM 81 held by a backup battery 80 (consisting of lithium battery). The computer unit 51 is initiated by the clock supplied via a clock line 76 from an oscillator 57. 54 is a battery for supplying a constant power supply voltage to the circuit in accordance with the on/off state of a power supply switch 52. 53 is a power supply voltage monitor IC for monitoring the voltage state to be applied to the computer unit 51 to send out a reset signal via a reset line 55 to the computer unit 51. 56 is a relay switch which is switched on/off by a relay drive circuit 73. 58 is a divider circuit for dividing in frequency the clock supplied via a clock line from the oscillator 57 to send out divided clock having a predetermined frequency to a counter circuit 59. 60 is a latch circuit for latching received electric field strength, which is detected by the radio transmit-receive unit 62 and then transmitted via an A/D converter output line 64 after A/D conversion by an A/D converter 61. 63 is an antenna, 65 is an open collector inverter which sends out a reset signal to a flip-flop 70 depending on the state of a reset control signal input via a reset control signal line 75 to which a resistor 78 having its one end grounded is connected. 74 is a reset line for outputting the reset signal output from the open collector inverter 65 to the flip-flop 70. The reset line 74 is pulled up by a resistor 66. 67 is an open collector inverter which sends out the reset signal to the counter circuit 59 depending on the state of reset control signal input via a reset control signal line 79 to which a resistor 69 having its one end grounded is connected. 68 is a resistor for pulling up the voltage of counter input line. 82 is a substrate the packaged chip components of which are driven by a power supply VDD from a power supply line 71. 72 is a ground line with its one end connected to a ground line GND of the substrate 82. 76 is a latch data line for transferring received electric field strength latched in the latch circuit 60 into the computer unit 51. 77 is a communication line. Fig. 5 is a flowchart showing one example of a second radio communication processing procedure in a portable electronic device according to the present invention. Note that (1) to (9) indicate each step. First, if power switch 52 is turned on, the reset control signal lines 79, 75 are at "LOW" in the initial state, whereby the counter 59 carries out after the elapse of e.g., 30msec, the flip-flop 70 sets the output Q to "HIGH", the relay driving circuit 73 turns on the relay switch 56, the compunter unit 51 is reset via the reset line 55 and sets the reset control signal line 79 to "HIGH", and then initialization process is executed (1). Then, the computer unit 51 is checked to determine whether to start the radio communication (2), in which if the answer is NO, the computer unit 51 executes other process (3) and the procedure returns to step (2). On the other hand, if the determination at step (2) is YES, the radio transmit-receive unit 62 receives all the channels one by one to execute carrier sense process (the detail procedure will be described later) for retrieving the channel having a predetermined electric field strength or less. Then, the presence or absence of any vacant channel is determined (5), in which if the answer is NO, the computer unit 51 displays a message "NO VACANT CHANNEL COMMUNICATION UNABLE" on a display unit, not shown (6), and the procedure returns to step (2). On the other hand, if the determination at step (5) is YES, an arbitrary vacant channel, for example, a channel having the smallest channel number among the vacant channels, is selected (7). Then, communication is performed through selected channel, that is, the computer unit 51 communicates data with the radio transmit-receive unit 62 via the communication line 77, with data exchange (8), and the end of data communication is judged (9), in which the procedure returns to step (2) if the answer is YES, or otherwise to step (8). Referring now to flowchart as shown in Fig. 6, processing operation of carrier sense as shown in Fig. 5 will be described below. Fig. 6 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 5. Note that (1) to (8) indicate each step. First, data for setting transmit-receive channel is set to zero (1). At this step, the radio transmit-receive unit 62 has no channel setting. Then, the computer unit 51 sets channel (N=N+1) in the radio transmit-receive unit 62 (2). Then, the reset control signal line 79 is set to "LOW" (3), and subsequently the reset control signal line 75 is set to "HIGH" (4). Thereby, the flip-flop 70 is reset, the output Q is at "LOW", the relay driving circuit 73 is kept in the off state, and the power supply to the computer unit 51 is kept in the off state. Therefore, the reset control signal line 75 is kept in the off state. Then, the procedure waits for a predetermined time to elapse until the counter 59 outputs a ripple carry-out (5). If the counter 59 outputs a ripple carry-out after the elapse of e.g., 30msec, the Q output of flip-flop 70 is kept in "HIGH" state, the relay driving circuit 73 is kept in "ON" state, and the power supply to the computer unit 51 is turned on. However, the reset control signal lines 75, 79 are kept in "LOW" state, because the computer 51 has a high impedance when the power is turned on. Then, if a ripple carry-out is output, backed up RAM 81 is referred to and it is recognized that a carrier sense value is set in the latch data line 76 (6). Then, latch data latched in the latch circuit 60 is read via the latch data line 76 to recognize the electric field strength of receiving channel (7). Then, a determination is performed as to whether or not the signal strength of each of all the channels is read (N=10 (where channel number N is e.g., from 1 to 10)) (9), in which if the answer is YES, the procedure returns to main procedure, or otherwise returns to step (2) to repeat the above processing. As above described, in the present invention, if a communication processing request from the radio transmit-receive unit occurs, control means sets the system state of the computer means (computer unit 51) being activated to a rest state, timer means starts clocking the signal receiving time of the radio transmit-receive unit when the system state of the computer means is kept in rest state, and holding means holds electric field strength of carrier received by the radio transmit-receive unit upon the termination of clocking by the timer means. And the control means switches the system state of the computer means being at rest to an active state, based on the end state of clocking by the timer means, to restart the activation of the computer means, whereby the radio transmit-receive unit can perform the communication processing stably, without being affected by high frequency noise arising with the system activation of the computer means. Also, the control means is configured to set the system state to a rest state by shutting down the power supply to the computer means, whereby the radio transmit-receive unit can perform the communication processing stably, without being affected by high frequency noise arising with the system activation of the computer means, by stopping the occurrence of high frequency noise of the computer means temporarily. Further, the control means is configured to set the system state to a rest state by resetting the computer means, whereby the radio transmit-receive unit can perform the communication processing stably, while the influence of high frequency noise arising with the system activation of the computer means is relieved by suppressing the occurrence of high frequency noise of the computer means temporarily. Accordingly, there is the effect that an inexpensive and small apparatus can be provided, with looser limitations in the circuit arrangement between the computer means and the radio transmit-receive unit, and a simpler shielding measure for the computer means. Fig. 7 is a block diagram for explaining a configuration of a portable electronic device according to one embodiment of the present invention. In the figure, 201 is a computer unit, comprising a keyboard for the input of information or instructions, a display unit for displaying input information or processed result, a memory for storing data and processing procedures as shown in flowcharts as thereafter described, processing means for processing data in accordance with processing procedure stored in the memory, and communication interface for communicating the information processed by processing procedure to the outside. The computer unit 201 is connected to a sub-CPU 202 via a control line 208, the sub-CPU 202 comprising a memory for storing data and programs for executing processing procedures as shown in flowcharts as thereafter described, processing means for processing data in accordance with the program stored in the memory, and a communication interface for communicating the information processed by processing means to the outside. The sub-CPU 202 communicates with the computer unit 201 for the transmission of information. The computer unit 201 is initiated upon a clock supplied from an oscillation circuit 214 via a clock line 212 with a reset signal 207 released. The clock supplied via the clock line 212 from the oscillation circuit 214 is divided in frequency by a divider circuit 215, and an output 213 after dividing into a frequency of e.g., 2msec is output via a low-pass filter 219 to a counter 216. 203 is a radio transmit-receive unit for communicating with an external equipment, not shown, via an antenna 204. A received electric field strength detected by the radio transmit-receive unit 203 is A/D converted by an A/D converter 218, and then latched in a latch circuit 217 via an A/D converter output line 225. The latch circuit 217 may be either of a first-in first-out system of memory and an addressing system, when storing the received electric field strength for a plurality of channels. 205 is a battery for supplying power supply voltage in accordance with the on/off state of a power supply switch 211. 206 is a power supply monitor IC for monitoring the power supply voltage state from the battery 205 to send out a reset signal via a computer reset line 207 to the computer unit 201 and an AND gate 224. The AND gate 224 sends out the reset signal via a sub-CPU reset line 210 to the sub-CPU 202, based on the reset signal and the output state from the computer unit 201. 220 is a ripple carry-out of the counter 216, 221 is a signal strength detection line, and 222 is a latch data output line for outputting electric field strength data latched in the latch circuit 217 to the sub-CPU 202. 223 is a reset line for transferring a counter control signal from the computer unit 201 to the counter 216. 209 is a control line, 226 is a reset signal from the computer unit 201 to the sub-CPU 202, and 227 is an interrupt signal. In the portable electronic device thus constituted, if a communication processing request from the radio transmit-receive unit 203 occurs, the computer unit 201 releases the reset state of the control line 223, and sets the sub-CPU 202 to a reset state via the control line 226. Timer means (counter 216) starts clocking upon the releasing of the reset state via the control line 223, nad holding means (latch circuit 217) holds electric field strength information of carrier (with a ripple carry-out signal 220 from the counter 216) which the radio transmit-receive unit 203 has received upon the termination of clocking by the timer means (counter 216). And the control means (computer unit 201) releases the system activation state of the computer means (sub-CPU 202) being at rest from the reset state via the control line 226, based on the end state of clocking by the timer means (counter 216) (upon the occurrence of n interrupt signal 227 from the counter 216), to restart the activation of the computer means (sub-CPU 202), whereby the radio transmit-receive unit 203 can search for available channel having a defined electric field strength or less and perform the communication processing with that channel in a stable manner, without being affected by high frequency noise arising with the operation of the computer means (sub-CPU 202 in this embodiment). Fig. 8 is a flowchart showing one example of a first radio transmit-receive processing procedure in a portable electronic device according to the present invention. Note that (1) to (9) indicate each step. First, if power switch 211 is turned on, computer unit 201 is reset upon a reset signal sent out via the computer unit reset line 207 by the power supply monitor IC 206, and sub-CPU 202 is reset upon a reset signal sent out via the sub-CPU reset line 210 (1). Then, the computer unit 201 is checked to determine whether to start the radio communication (2), in which if the answer is NO, the computer unit 201 executes other process (3) and the procedure returns to step (2). On the other hand, if the determination at step (2) is YES, the radio transmit-receive unit 203 receives all the channels one by one to execute carrier sense process (the detail procedure will be described later) for retrieving the channel having a predetermined electric field strength or less (4). Then, the presence or absence of any vacant channel determined (5), in which if the answer is NO, the computer unit 201 displays a message "NO VACANT CHANNEL COMMUNICATION UNABLE" on a display unit, not shown (6), and the procedure returns to step (2). On the other hand, if the determination at step (5) is YES, an arbitrary vacant channel, for example, a channel having the smallest channel number among the vacant channels, is selected (7). Then, communication is performed through selected channel, that is, the computer unit 201 communicates data with the sub-CPU 202, which in turn communicates data with the radio transmit-receive unit 203 (8), and the end of data communication is judged (9), in which the procedure returns to step (2) if the answer is YES, or otherwise to step (8). Referring now to flowchart as shown in Fig. 9, processing operation of carrier sense as shown in Fig. 8 will be described below. Fig. 9 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 8. Note that (1) to (9) indicate each step. First, data for setting transmit-receive channel is set to zero (1). At this step, the radio transmit-receive unit 203 has no channel setting. Then, the computer unit 201 sets channel (N=N+1) in the radio transmit-receive unit 203 via the sub-CPU 202 (2). Then, the sub-CPU 202 is kept in reset state (3), and reset line 223 of counter 216 is released (4). Then, waiting for a predetermined time to elapse until the counter 216 outputs a ripple carry-out 220 (5), and if the ripple carry-out 220 is output, the computer unit 201 senses it via interrupt line 227, and the sub-CPU 202 is released from reset state upon the reset signal (6). Then, ripple carry-out signal 220 is output by a processing to be carried out during waiting time of the above step (5), that is, if the input of the counter 216 is counted (2msec for one period) by, for example, fifteen times, and latch data latched in latch circuit 217 by a processing of latching the value of A/D converter 218 in latch circuit 217 is read by the sub-CPU 202 via the latch data output line 222, and transmitted via the control line 208 to the computer unit 201 (7). Then, the reset line 223 is kept in reset state (8). And a determination is performed as to whether or not the signal strength of each of all the channels is read (N=10 (where channel number N is e.g., from 1 to 10)) (9), in which if the answer is YES, the procedure returns to main procedure, or otherwise returns to step (2) to repeat the above processing. In the above embodiment, the radio transmit-receive unit 203 is prevented from experiencing influence of noise arising in the processing of the sub-CPU 202 by resetting the sub-CPU 202 for a certain time until electric field strength output data of the radio transmit-receive unit 203 is held. Fig. 10 is a block diagram for explaining a configuration of a portable electronic device according to another embodiment of the present invention. In the figure, 251 is a computer unit containing RAM 281, the contents of RAM 281 held by a backup battery 280 (consisting of lithium battery). The computer unit 251 is initiated by the clock supplied via a clock line 299 from an oscillator 57 upon the releasing of the reset on the reset line 255. 254 is a battery for supplying a constant power supply voltage to the circuit in accordance with the on/off state of a power supply switch 252. 253 is a power supply voltage monitor IC for monitoring the voltage state to be applied to the computer unit 251 to send out a reset signal via a reset line 255 to the computer unit 251. 256 is a relay switch which is switched on/off by a relay drive circuit 273. 258 is a divider circuit for dividing in frequency the clock supplied via a clock line from the oscillator 257 to send out divided clock having a predetermined frequency to a counter circuit 259. 260 is a latch circuit for latching received electric field strength, which is detected by the radio transmit-receive unit 262 and then transmitted via an A/D converter output line 264 after A/D conversion by an A/D converter 261. 263 is an antenna, 265 is an open collector inverter which sends out a reset signal to a flip-flop 270 depending on the state of a reset control signal input via a reset control signal line 275 to which a resistor 278 having its one end grounded is connected. 274 is a reset line for outputting the reset signal output from the open collector inverter 265 to the flip-flop 270. The reset line 274 is pulled up by the resistor 266. 267 is an open collector inverter which sends out the reset signal to the counter circuit 259 depending on the state of control signal input via a reset control signal line 279 to which a resistor 269 having its one end grounded is connected. 268 is a resistor for pulling up the voltage of counter input line. 282 is a substrate the packaged chip components of which are driven by a power supply VDD from a power supply line 271. 272 is a ground line with its one end connected to a ground line GND of the substrate 282. 276 is a latch data line for transferring received electric field strength latched in the latch circuit 260 into the computer unit 251. 277 is a communication line. Fig. 11 is a flowchart showing one example of a second radio communication processing procedure in a portable electronic device according to the present invention. Note that (1) to (9) indicate each step. First, if power switch 252 is turned on, the reset control signal lines 279, 275 are at "LOW" in the initial state, whereby the counter 259 carries out after the elapse of e.g., 30msec, the flip-flop 270 sets the output Q to "HIGH", the relay driving circuit 273 turns on the relay switch 256, the computer unit 251 is reset via the reset line 255 and sets the reset control signal 279 to "HIGH", and then initialization process is executed (1). Then, the computer unit 251 is checked to determine whether to start the radio communication (2), in which if the answer is NO, the computer unit 251 executes other process (3) and the procedure returns to step (2). On the other hand, if the determination at step (2) is YES, the radio transmit-receive unit 262 receives all the channels one by one to execute carrier sense process (the detail procedure will be described later) for retrieving the channel having a predetermined electric field strength or less (4). Then, the presence or absence of any vacant channel is determined (5), in which if the answer is NO, the computer unit 251 displays a message "NO VACANT CHANNEL COMMUNICATION UNABLE" on a display unit, not shown (6), and the procedure returns to step (2). On the other hand, if the determination at step (5) is YES, an arbitrary vacant channel, for example, a channel having the smallest channel number among the vacant channels, is selected (7). Then, communication is performed through selected channel, that is, the computer unit 251 communicates data with the radio transmit-receive unit 262 via the communication line 277, with data exchange (8), and the end of data communication is judged (9), in which the procedure returns to step (2) if the answer is YES, or otherwise to step (8). Referring now to flowchart as shown in Fig. 12, processing operation of carrier sense as shown in Fig. 11 will be described below. Fig. 12 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 11. Note that (1) to (8) indicate each step. First, data for setting transmit-receive channel is set to zero (1). At this step, the radio transmit-receive unit 262 has no channel setting. Then, the computer unit 251 sets channel (N=N+1) in the radio transmit-receive unit 262 (2). Then, the reset control signal line 279 is set to "LOW" (3), and subsequently the reset control signal line 275 is set to "HIGH" (4). Thereby, the flip-flop 270 is reset, the output Q is at "LOW", the relay driving circuit 273 is kept in the off state, and the power supply to the computer unit 251 is kept in the off state. Therefore, the reset control signal lines 275, 279 are kept in "LOW". Then, the procedure waits for a predetermined time to elapse until the counter 259 outputs a ripple carry-out (5). If the counter 259 outputs a ripple carry-out after the elapse of e.g., 30msec, the Q output of flip-flop 270 is kept in "HIGH" state, the relay driving circuit 273 is kept in "ON" state, and the power supply to the computer unit 251 is turned on. However, the reset control signal lines 275, 279 are kept in "LOW" state owing to resistors 269, 278, because there is no output from the computer unit 251 when the power of computer unit 251 is turned on. Then, the computer unit 251 refers to backed up RAM 281 and recognizes that a carrier sense value is set in the latch data line 276 (6). (the computer unit is turned off by the flag state of RAM 281, because of a carrier sense processing, and reset via the reset line 255, thereby recognizing the initiation.) Then, latch data latched in the latch circuit 60 is read via the latch data line 276 to recognize the electric field strength of receiving channel (7). Then, a determination is performed as to whether or not the signal strength of each of all the channels is read (N=10 (where channel number N is e.g., from 1 to 10)) (8), in whcih if the answer is YES, the procedure returns to main procedure, or otherwise returns to step (2) to repeat the above processing. Fig. 13 is a flowchart showing another embodiment of the present invention. Note that the block diagram and the main flowchart are the same as those of embodiment shown in Figs. 7 and 8. Referring now to flowchart as shown in Fig. 13, processing operation of carrier sense as shown in Fig. 8 will be described below. Fig. 13 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 8. Note that (1) to (9) indicate each step. First, data for setting transmit-receive channel is set to zero (1). At this step, the radio transmit-receive unit 203 has no channel setting. Then, the computer unit 201 sets channel (N=N+1) in the radio transmit-receive unit 203 via the sub-CPU 202 (2). Then, the computer unit 201 releases the reset line 223 of counter 216 (3), and keeps the sub-CPU 202 in halt state by executing a halt instruction (4). Then, waiting for a predetermined time to elapse until the counter 216 outputs a ripple carry-out 220 (5), and if the ripple carry-out 220 is output, the computer unit 201 is released from the halt state via the interrupt line 227 (6). Then, ripple carry-out signal 220 is output by a processing to be carried out during waiting time of the above step (5), that is, if the input of the counter 216 is counted (2msec for one period) by, for example, fifteen times, and latch data latched in latch circuit 217 by a processing of latching the value of A/D converter 218 in latch circuit 217 is read by the sub-CPU 202 via the latch data output line 222, and transmitted via the control line 208 to the computer unit 201 (7). Then, the reset line 223 is kept in reset state (8). And a determination is performed as to whether or not the signal strength of each of all the channels is read (N=10 (where channel number N is e.g., from 1 to 10)) (9), in which if the answer is YES, the procedure returns to main procedure, or otherwise returns to step (2) to repeat the above processing. In the above embodiment, the radio transmit-receive unit 203 is prevented from experiencing influence of noise arising in the processing of the computer unit 201 by halting the computer unit 201 for a certain time until electric field strength output data of the radio transmit-receive unit 203 in held. Fig. 14 is a flowchart showing another embodiment of the present invention. Note that the block diagram and the main flowchart are the same as those of embodiment shown in Figs. 7 and 8. Referring now to flowchart as shown in Fig. 14, processing operation of carrier sense as shown in Fig. 8 will be described below. Fig. 14 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 8. Note that (1) to (11) indicate each step. First, data for setting transmit-receive channel is set to zero (1). At this step, the radio transmit-receive unit 203 has no channel setting. Then, the computer unit 201 sets channel (N=N+1) in the radio transmit-receive unit 203 via the sub-CPU 202 (2). Then, the computer unit 201 keeps the sub-CPU2 in halt state (3), releases the reset line 223 of counter 216 (4), and keeps itself in halt state (5). Then, waiting for a predetermined time to elapse until the counter 216 outputs a ripple carry-out 220 (6), and if the ripple carry-out 220 is output, the computer unit 201 releases itself from the halt state via the interrupt line 227 (7). Then, the computer unit 201 releases the sub-CPU 202 from the halt state (8). Then, ripple carry-out signal 220 is output by a processing to be carried out during waiting time of the above step (6), that is, if the input of the counter 216 is counted (2msec for one period) by, for example, fifteen times, and latch data latched in latch circuit 217 by a processing of latching the value of A/D converter 218 in latch circuit 217 is read by the sub-CPU 202 via the latch data output line 222, and transmitted via the control line 208 to the computer unit 201 (9). Then, the reset line 223 is kept in reset state (10). And a determination is performed as to whether or not the signal strength of each of all the channels is read (N=10, where channel number N is e.g., from 1 to 10) (11), in which if the answer is YES, the procedure returns to main procedure, or otherwise returns to step (2) to repeat the above processing. In the above embodiment, the radio transmit-receive unit 203 is prevented from experiencing influence of noise arising in the processing of the computer unit 201 and the sub-CPU 202 by halting the computer unit 201 and the sub-CPU 202 for certain time until electric field strength output data of the radio transmit-receive unit 203 is held. Fig. 15 is a block diagram for explaining a configuration of a portable electronic device according to one embodiment of the present invention. In the figure, 301 is a computer unit, comprising a keyboard for the input of information or instructions, a display unit for displaying input information or processed result, a memory for storing data and processing procedures as shown in flowcharts as thereafter described, processing means for processing data in accordance with processing procedure stored in the memory, and communication interface for communicating the information processed by processing procedure to the outside. The computer unit 301 is connected to a sub-CPU 302 via a control line 308, the sub-CPU 302 comprising a memory for storing data and programs for executing processing procedures as shown in flowcharts as thereafter described, processing means for processing data in accordance with the program stored in the memory, and a communication interface for communicating the information processed by processing procedure to the outside. The sub-CPU 302 communicates with the computer unit 301 for the transmission of information. The computer unit 301 is initiated upon a clock supplied from an oscillation circuit 314 via a clock line 312 with a reset signal 307 released. The clock supplied via the clock line 312 from the oscillation circuit 314 is divided in frequency by a divider circuit 315, and an output 313 after dividing into a frequency of e.g., 2msec is output via a low-pass filter 319 to a counter 316. 303 is a radio transmit-receive unit for communicating with an external equipment, not shown, via an antenna 304. A received electric field strength detected by the radio transmit-receive unit 303 is A/D converted by an A/D converter 318, and then latched in a latch circuit 317 via an A/D converter output line 325. The latch circuit 317 may be either of a first-in first-out system of memory and an addressing system, when storing the received electric field strength for a plurality of channels. 305 is a battery for supplying power supply voltage in accordance with the on/off state of a power supply switch 311. 306 is a power supply monitor IC for monitoring the power supply voltage state from the battery 305 to send out a reset signal via a computer reset line 307 to the computer unit 301 and an AND gate 324. The AND gate 324 sends out the reset signal via a sub-CPU reset line 310 to the sub-CPU 302, based on the reset signal and the output state from the computer unit 301. 320 is a ripple carry-out of the counter 316, 321 is a signal strength detection line, and 322 is a latch data output line for outputting electric field strength data latched in the latch circuit 317 to the sub-CPU 302. 323 is a reset line for transferring a counter control signal from the computer unit 301 to the counter 316. 309 is a control line, 326 is a reset signal from the computer unit 301 to the sub-CPU 302, and 327 is an interrupt signal. In the portable electronic device thus constituted, if a communication processing request from the radio transmit-receive unit 303 occurs, the computer unit 301 releases the reset state of the control line 323, and sets the sub-CPU 302 to a reset state via the control line 326. Timer means (counter 316) starts clocking upon the releasing of the reset state on the control line 323, and holding means (latch circuit 317) holds electric field strength information of carrier (with a ripple carry-out signal 320 from the counter 316) which the radio transmit-receive unit 303 has received upon the termination of clocking by the timer means (counter 316). And the control means (computer unit 301) releases the system activation state of the computer means (sub-CPU 302) being at rest from the reset state via the control line 326, based on the end state of clocking by the timer means (counter 316) (upon the occurrence of an interrupt signal 327 from the counter 316), to restart the activation of the computer means (sub-CPU 302), whereby the radio transmit-receive unit 303 can search for available channel having a defined electric field strength or less and perform the communication processing with that channel in a stable manner, without being affected by high frequency noise arising with the operation of the computer means (sub-CPU 302 in this embodiment). Fig. 16 is a flowchart showing one example of a first radio communication processing procedure in a portable electronic device according to the present invention. Note that (1) to (9) indicate each step. First, if power switch 311 is turned on, computer unit 301 is reset upon a reset signal sent out via the computer unit reset line 307 by the power supply monitor IC 306, and sub-CPU 302 is reset upon a reset signal sent out via the reset line 310 of sub-CPU 302 (1). Then, the computer unit 301 is checked to determine whether to start the radio communication (2), in which if the answer is NO, the computer unit 301 executes other process (3) and the procedure returns to step (2). On the other hand, if the determination at step (2) is YES, the radio transmit-receive unit 303 receives all the channels one by one to execute carrier sense process (the detail procedure will be described later) for retrieving the channel having a predetermined electric field strength or less (4). Then, the presence or absence of any vacant channel is determined (5), in which if the answer is NO, the computer unit 301 displays a message "NO VACANT CHANNEL COMMUNICATION UNABLE" on a display unit, not shown (6), and the procedure returns to step (2). On the other hand, if the determination at step (5) is YES, an arbitrary vacant channel, for example, a channel having the smallest channel number among the vacant channels, is selected (7). Then, communication is performed through selected channel, that is, the computer unit 301 communicates data with the sub-CPU 302, which in turn communicates data with the radio transmit-receive unit 303 (8), and the end of data communication is judged (9), in which the procedure returns to step (2) if the anser is YES, or otherwise to step (8). Referring now to flowchart as shown in Fig. 17, processing operation of carrier sense as shown in Fig. 16 will be described below. Fig. 17 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 16. Note that (1) to (9) indicate each step. First, data for setting transmit-receive channel is set to zero (1). At this step, the radio transmit-receive unit 303 has no channel setting. Then, the computer unit 301 sets channel (N=N+1) in the radio transmit-receive unit 303 via the sub-CPU 302 (2). Then, the sub-CPU 302 is kept in reset state (3), and reset line 323 of counter 316 is released (4). Then, waiting for a predetermined time to elapse until the counter 316 outputs a ripple carry-out 320 (5), and if the ripple carry-out 320 is output, the computer unit 301 senses it via interrupt line 327, and the sub-CPU 302 is released from reset state upon the reset signal 326 (6). Then, ripple carry-out signal 320 is output by a processing to be carried out during waiting time of the above step (5), that is, if the input of the counter 316 is counted (2msec for one period) by, for example, fifteen times, and latch data latched in latch circuit 317 by a processing of latching the value of A/D converter 318 in latch circuit 317 is read by the sub-CPU 302 via the latch data output line 322, and transmitted via the control line 308 to the computer unit 301 (7). Then, the reset line 323 is kept in reset state (8). And a determination is performed as to whether or not the signal strength of each of all the channels is read (N=10 (where channel number N is e.g., from 1 to 10)) (9), in which if the answer is YES, the procedure returns to main procedure, or otherwise returns to step (2) to repeat the above processing. In the above embodiment, the radio transmit-receive unit 303 is prevented from experiencing influence of noise arising in the processing of the sub-CPU 302 by resetting the sub-CPU 302 for a certain time until electric field strength output data of the radio transmit-receive unit 303 is held. Fig. 18 is a block diagram showing a configuration of a portable electronic device according to another embodiment of the present invention. In the figure, 351 is a computer unit containing RAM 381, the contents of RAM 381 held by a backup battery 380 (consisting of lithium battery). The computer unit 351 is initiated by the clock oscillating within the computer unit 351 upon the releasing of the reset on the reset line 355. 354 is a battery for supplying a constant power supply voltage to the circuit in accordance with the on/off state of a power supply switch 352. 353 is a power supply voltage monitor IC for monitoring the voltage state to be applied to the computer unit 351 to send out a reset signal via a reset line 355 to the computer unit 351. 356 is a relay switch which is switched on/off by a relay drive circuit 373. 360 is a latch circuit for latching received electric field strength, which is detected by the radio transmit-receive unit 362 and then transmitted via an A/D converter output line 364 after A/D conversion by an A/D converter 361. 363 is an antenna, 365 is an open collector inverter which sends out a reset signal to a flip-flop 370 depending on the state of a reset control signal input via a reset control signal line 375 to which a resistor 378 having its one end grounded is connected. 374 is a reset line for outputting the reset signal output from the open collector inverter 365 to the flip-flop 370. The reset line 374 is pulled up by the resistor 366. 367 is an open collector inverter which sends out the reset signal to the counter circuit 359 depending on the state of control signal input via a reset control signal line 379 to whcih a resistor 369 having its one end grounded is connected. 368 is a resistor for pulling up the voltage of counter input line. 382 is a substrate the packaged chip components of which are driven by a power supply VDD from a power supply line 371. 372 is a ground line with its one end connected to a ground line GND of the substrate 382. 376 is a latch data line for transferring received electric field strength latched in the latch circuit 360 into the computer unit 351. 377 is a communication line. Fig. 19 is a flowchart showing one example of a second radio communication processing procedure in a portable electronic device according to the present invention. Note that (1) to (9) indicate each step. First, if power switch 352 is turned on, the reset control signal lines 379, 375 are at "LOW" in the initial state, whereby the counter 359 carries out after the elapse of e.g., 30msec, the flip-flop 370 sets the output Q to "HIGH", the relay driving circuit 373 turns on the relay switch 356, the computer unit 351 is reset via the reset line 355 and sets the reset control signal 379 to "HIGH", and then initialization process is executed (1). Then, the computer unit 351 is checked to determine whether to start the radio communication (2), in which if the answer is NO, the computer unit 351 executes other process (3) and the procedure returns to step (2). On the other hand, if the determination at step (2) is YES, the radio transmit-receive unit 362 receives all the channels one by one to execute carrier sense process (the detail procedure will be described later) for retrieving the channel having a predetermined electric field strength or less (4). Then, the presence or absence of any vacant channel is determined (5), in which if the answer is NO, the computer unit 351 displays a message "NO VACANT CHANNEL COMMUNICATION UNABLE" on a display unit, not shown (6), and the procedure returns to step (2). On the other hand, if the determination at step (5) is YES, an arbitrary vacant channel, for example, a channel having the smallest channel number among the vacant channels, is selected (7). Then, communication is performed through selected channel, that is, the computer unit 351 communicates data with the radio transmit-receive unit 362 via the communication line 377, with data exchange (8), and the end of data communication is judged (9), in which the procedure returns to step (2) if the answer is YES, or otherwise to step (8). Referring now to flowchart as shown in Fig. 20, processing operation of carrier sense as shown in Fig. 19 will be described below. Fig. 20 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 19. Note that (1) to (8) indicate each step. First, data for setting transmit-receive channel is set to zero (1). At this step, the radio transmit-receive unit 362 has no channel setting. Then, the computer unit 351 sets channel (N=N+1) in the radio transmit-receive unit 362 (2). Then, the reset control signal line 379 is set to "LOW" (3), and subsequently the reset control signal line 375 is set to "HIGH" (4). Thereby, the flip-flop 370 is reset, the output Q is at "LOW", the relay driving circuit 373 is kept in the off state, and the power supply to the computer unit 351 is kept in the off state. Therefore, the reset control signal lines 375, 379 are kept in "LOW". Then, the procedure waits for a predetermined time to elapse until the counter 359 outputs a ripple carry-out (5). If the counter 359 outputs a ripple carry-out after the elapse of e.g., 30msec, the Q output of flip-flop 370 is kept in "HIGH" state, the relay driving circuit 373 is kept in "ON" state, and the power supply to the computer unit 351 is turned on. However, the reset control signal lines 375, 379 are kept in "LOW" state, owing to resistors 369, 378, because there is no output from the computer unit 351 when the power of computer unit 351 is turned on. Then, the computer unit 351 refers to backed up RAM 381 and recognizes that a carrier sense value is set in the latch data line 376 (6). (The computer unit is turned off by the flag state of RAM 381, because of a carrier sense processing, and reset via the reset line 355, thereby recognizing the intiation.) Then, latch data latched in the latch circuit 360 is read via the latch data line 376 to recognize the electric field strength of receiving channel (7). Then, a determination is performed as to whether or not the signal strength of each of all the channels is read (N=10 (where channel number N is e.g., from 1 to 10)) (8), in which if the answer is YES, the procedure returns to main procedure, or otherwise returns to step (2) to repeat the above processing. Fig. 21 is a flowchart showing another embodiment of the present invention. Note that the block diagram and the main flowchart are the same as those of embodiment shown in Figs. 15 and 16. Referring now to flowchart as shown in Fig. 21, processing operation of carrier sense as shown in Fig. 16 will be described below. Fig. 21 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 16. Note that (1) to (9) indicate each step. First, data for setting transmit-receive channel is set to zero (1). At this step, the radio transmit-receive unit 303 has no channel setting. Then, the computer unit 301 sets channel (N=N+1) in the radio transmit-receive unit 303 via the sub-CPU 302 (2). Then, the reset line 323 of counter 316 is released (3). The computer unit 301 is kept in halt state by executing a halt instruction (4). Then, waiting for a predetermined time to elapse until the counter 316 outputs a ripple carry-out 320 (5), and if the ripple carry-out 320 is output, the computer unit 301 is released from the halt state via the interrupt line 327 (6). Then, ripple carry-out signal 320 is output by a processing to be carried out during waiting time of the above step (5), that is, if the input of the counter 316 is counted (2msec for one period) by, for example, fifteen times, and latch data latched in latch circuit 317 by a processing of latching the value of A/D converter 318 in latch circuit 317 is read by the sub-CPU 302 via the latch data output line 322, and transmitted via the control line 308 to the computer unit 301 (7). Then, the reset line 323 is kept in reset state (8). And a determination is performed as to whether or not the signal strength of each of all the channels is read (N=10 (where channel number N is e.g., from 1 to 10)) (9), in which if the answer is YES, the procedure returns to main procedure, or otherwise returns to step (2) to repeat the above processing. In the above embodiment, the radio transmit-receive unit 303 is prevented from experiencing influence of noise arising in the processing of the computer unit 301 by halting the computer unit 301 for a certain time until electric field strength output data of the radio transmit-receive unit 303 is held. Fig. 22 is flowchart showing another embodiment of the present invention. Note that the block diagram and the main flowchart are the same as those of embodiment shown in Figs. 15 and 16. Referring now to flowchart as shown in Fig. 22, processing operation of carrier sense as shown in Fig. 16 will be described below. Fig. 22 is a flowchart showing in detail one example of a carrier sense processing procedure as shown in Fig. 16. Note that (1) to (11) indicate each step. First, data for setting transmit-receive channel is set to zero (1). At this step, the radio transmit-receive unit 303 has no channel setting. Then, the computer unit 301 sets channel (N=N+1) in the radio transmit-receive unit 303 via the sub-CPU 302 (2). Then, the computer unit 301 keeps the sub-CPU 302 in halt state (3), releases the reset line 323 of counter 316 (4), and keeps itself in halt state (5). Then, waiting for a predetermined time to elapse until the counter 316 outputs a ripple carry-out 320 (6), and if the ripple carry-out 320 is output, the computer unit 301 releases itself from the halt state via the interrupt line 327 (7). Then, the computer unit 301 releases the sub-CPU 302 from the halt state (8). Then, ripple carry-out signal 320 is output by a processing to be carried out during waiting time of the above step (6), that is, if the input of the counter 316 is counted (2msec for one period) by, for example, fifteen times, and latch data latched in latch circuit 317 by a processing of latching the value of A/D converter 318 in latch circuit 317 is read by the sub-CPU 302 via the latch data output line 322, and transmitted via the control line 308 to the computer unit 301 (9). Then, the reset line 323 is kept in reset state (10). And a determination is performed as to whether or not the signal strength of each of all the channels is read (N=10 (where channel number N is e.g., from 1 to 10)) (11), in which if the answer is YES, the procedure returns to main procedure, or otherwise returns to step (2) to repeat the above processing. In the above embodiment, the radio transmit-receive unit 303 is prevented from experiencing influence of noise arising in the processing of the computer unit 301 and the sub-CPU 302 by halting the computer unit 301 and the sub-CPU 302 for a certain time until electric field strength output data of the radio transmit-receive unit 303 is held. A radio transmit-receive unit can perform the communication processing stably without being affected by high frequency noise with the system activation of a computer unit, whereby if a communication processing request from the radio transmit-receive unit occurs, the computer unit sets the system state of a sub-CPU being activated to a rest state, a counter starts clocking the signal receive time of the radio transmit-receive unit when the system state of the sub-CPU is in a rest state, and a latch circuit holds electric field strength information of carrier received by the radio transmit-receive unit upon the termination of clocking by the counter. And the computer unit switches the system state of the sub-CPU being at rest to an active state, based on the end state of clocking by the counter, to restart the activation of the computer unit.

Claims: An electronic device comprising a) a radio transmit-receive unit (3; 62; 203; 262; 303; 362) for performing radio communication processing with an external device via an antenna (4; 63; 204; 263; 304; 363); b) computer means (2; 51; 202; 251; 302; 351) for communicating with said radio transmit-receive unit; and c) control means (1; 70; 201; 270; 301; 370) for setting said computer means to a rest state, characterized by d) timer means (16; 59; 216; 259; 316; 359) for clocking a signal receive time of said radio transmit-receive unit in accordance with the setting activation of said control means; and e) holding means (17; 60; 217; 260; 317; 360) for holding an electric field strength information of a carrier received by said radio transmit-receive unit, f) wherein said control means is arranged to set said computer means to said rest state until said electric field strength information is held in said holding means and to switch the rest state of said computer means to an active state based on the end state of clocking by said timer means in order to perform said radio communication processing. An electronic device according to claim 1, characterized in that said control means ( 70; 270; 370) is arranged to set the system state to a rest state by shutting down a power supply to said computer means (51; 251; 351). An electronic device according to claim 1, characterized in that said control means (1; 201; 301) is arranged to set the system state to a rest state by resetting said computer means (2; 202; 302). An electronic device according to claim 1, characterized in that said control means (1; 201; 301) is arranged to set the system state to a rest state by keeping said computer means (2; 202; 302) itself in a halt state. An electronic device according to any one of claims 1 to 4, characterized by another computer means (1; 201; 301) for processing desired information synchronously with a reference clock, wherein said control means (1; 201; 301) switches the rest state of said computer means (2; 202; 302) to an active state based on the end state of clocking by said timer means to set said electric field strength information held in said holding means by said computer means (2; 202; 302) to said other computer means (1; 201; 301). An electronic device according to claim 5, characterized in that said control means is arranged to set said computer means (2; 202; 302) and said other computer means (1; 201; 301) to the rest state and to switch the rest state of said computer means (2; 202; 302) and said other computer means (1; 201; 301) to an active state based on the end state of clocking by said timer means to set said electric field strength information held in said holding means by said computer means (2; 202; 302) to said other computer means (1; 201; 301). An electronic device according to claim 6, characterized in that said control means is arranged to set the system state to a rest state by shutting down a power supply to said computer means and said other computer means. An electronic device according to claim 6, characterized in that said control means (1; 201; 301) is arranged to set the system state to a rest state by resetting said computer means (2; 202; 302) and said other computer means (1; 201; 301). An electronic device according to claim 6, characterized in that said control means (1; 201; 301) is arranged to set the system state to a rest state by keeping said computer means (2; 202; 302) and said other computer means (1; 201; 301) themselves in a halt state.

Inventors: HAMANO SOJI, TANABE TAKAYUKI, HAMANO, SOJI, TANABE, TAKAYUKI, HAMANO, SOJI, C/O CANON KABUSHIKI KAISHA, Tanabe, Takayuki, c/o Canon Kabushiki Kaisha
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1993
Main classification: H04M1
IPC codes: H04B15, H04M1