Abstract:
A communication system. The system includes a transmission bus, a plurality of circuit apparatuses, and a management device. Each circuit apparatus comprises an external integrated circuit and a switch circuit. Each external integrated circuit is coupled to the transmission bus via the corresponding switch circuit. The management device monitors the status of the transmission bus and, when the status is determined as abnormal, switches at least one of the switch circuits to isolate at least one corresponding external integrated circuit from the transmission bus.

Description:
BACKGROUND  
       [0001]     The present invention relates to a transmission device, and more particularly to a transmission device for protecting a transmission bus of a communication system and a control method thereof.  
         [0002]     Computer systems comprise many integrated circuits (ICs), such as microprocessors, random access memories (RAMs), electrically erasable programmable read only memories (E 2 PROMs), liquid crystal display (LCD) drivers, or data converters. These ICs transmit data through a bus, such an as an inter-integrated circuit (I 2 C) bus.  
         [0003]      FIG. 1  is a schematic diagram of a conventional I 2 C connecting integrated circuits. Integrated circuits (ICs)  11 ˜ 14  transmit data through the I 2 C bus  15 . Only utilizing clock signal SCL and data signal SDA is characteristic of the I 2 C bus  15 .  
         [0004]     In an I 2 C bus, only one IC is designated as a master for controlling the clock signal SCL and others are designated as slave ICs. The master IC is unfixed such that each IC can be designated as a master IC.  
         [0005]     If the IC  11  is designated as a master, ICs  12 - 14  serve as slave ICs. Some factors, such as element aging, may cause the IC  11  abnormal such that the IC  11  outputs an incorrect clock signal SCL to hold the I 2 C bus  15 . Therefore, ICs  11 ˜ 14  cannot transmit data to each other and the computer system paralysis causes shutdown.  
         [0006]     In actual operation, since many ICs are connected via the I 2 C bus  15 , when the status of one IC is abnormal, a user cannot easily and directly find the abnormal IC. A conventional solution has been developed. First, a user opens a computer case and then finds the I 2 C bus. Next, the ICs are pulled by the user.  
         [0007]     When pulling out one IC, a user must test the operation of the I 2 C bus. If the I 2 C bus is still paralyzed, a user must continue pulling out other ICs until the paralysis is eliminated. If the number of abnormal ICs exceeds one, the user must insert the removed ICs and then pull the ICs out one by one, until all the abnormal ICs are found. This conventional solution is costly, time consuming and requires human intervention.  
       SUMMARY  
       [0008]     Embodiments of the invention provide a communication system comprising a transmission bus, a plurality of circuit apparatuses and a management device. Each circuit apparatus comprises an external integrated circuit and a switch circuit. Each external integrated circuit is coupled to the transmission bus via the corresponding switch circuit. The management device monitors the status of the transmission bus. When the status of the transmission bus is determined as abnormal, the management device switches at least one of the switch circuits to isolate at least one corresponding external integrated circuit from the transmission bus.  
         [0009]     Also provided is a transmission device transmitting data between a plurality of external integrated circuits. The transmission device comprises a transmission bus, a plurality of external connectors, and a management device. Each external connector comprises a slot and a switch circuit. Each external integrated circuit is able to couple to the transmission bus via one slot and the corresponding switch circuit. The management device monitors the status of the transmission bus. When the status of the transmission bus is determined as abnormal, the management device switches at least one of the switch circuits to isolate at least one corresponding external integrated circuit from the transmission bus.  
         [0010]     An embodiment of the invention additionally provides a control method, appropriate for a communication system comprising a transmission bus and a plurality of integrated circuits. A plurality of switch circuits are provided. Each switch circuit connects between the transmission bus and a corresponding integrated circuit. The status of the transmission bus is monitored. At least one switch circuit is switched to isolate at least one corresponding integrated circuit from the transmission bus and to retrieve a failed integrated circuit when the status is determined as abnormal. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The invention can be more fully understood by reading the subsequent detailed description and examples with reference made to the accompanying drawings, wherein:  
         [0012]      FIG. 1  is a schematic diagram of a conventional I 2 C connecting integrated circuits;  
         [0013]      FIG. 2  is a schematic diagram of a communication system according to an embodiment of the invention;  
         [0014]      FIG. 3  shows a control method of a computer system according to an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0015]     A bus interface, such as a system management bus (SM Bus), a universal controller interface bus (USB), a IEEE1394, a peripheral controller interface bus (PCI Bus), and an I 2 C bus, can be applied in the invention. Hereinafter, an I 2 C bus is given as an example.  
         [0016]      FIG. 2  is a schematic diagram of a communication system according to an embodiment of the invention. The communication system  20  comprises integrated circuits (ICs)  11 ˜ 14  and a transmission device  22 . ICs  11 ˜ 14  transmit data through the transmission device  22 .  
         [0017]     The transmission device  22  comprises an I 2 C bus  15 , slots  241 ˜ 244 , switch circuits  261 ˜ 265 , and a management device  280 . ICs  11 ˜ 14  can be inserted into slots  241 ˜ 244  to connect with the I 2 C bus  15  through switch circuits  261 ˜ 265 , respectively.  
         [0018]     The management device  280  is connected with the I 2 C bus  15  through switch circuit  265  for monitoring the status of the I 2 C bus  15  and switching the switch circuits  261 ˜ 265 . Since the management device  280  continuously or periodically monitors the status of the I 2 C bus  15 , the switch circuit  265  is generally turned on. The I 2 C bus  15  is coupled to terminals of the ICs  11 ˜ 14 , transmitting the clock signal SCL and data signal SDA.  
         [0019]     When the management device  280  determines the status of the I 2 C bus  15  as abnormal, for example the voltage level of the clock signal SCL or data signal SDA has not been changed during a preset time or the ICs are unable to transmit data through the I 2 C bus  15 , the management device  280  switches the switch circuits  261 ˜ 264  individually to isolate a corresponding IC from the I 2 C bus  15 . Once one of switch circuits  261 ˜ 264  is turned off and the I 2 C bus  15  is normal, it may be concluded that a corresponding isolated IC has failed. A failed IC can be isolated, in order to not disturb the signal transmission of others.  
         [0020]     When the switch circuits  261 ˜ 264  are all turned off and the status of the I 2 C bus  15  is abnormal, it is possible that the root cause of abnormality is in the management device  280  or I 2 C bus  15  itself. Thus, the switch circuit  265  can be turned off and if the ICs  11 ˜ 14  are still unable to transmit data through the I 2 C bus  15 , it can be determined that the failed has occurred in the I 2 C bus  15 .  
         [0021]     When the failed factor is detected, the management device  280  generates a warning signal, such as an alarm or a catchphrase, to notify user of the failed.  
         [0022]     If a failed IC has been isolated from the I 2 C bus  15 , the operation of the I 2 C bus  15  should resume normal operation even if the user does not immediately remove the abnormal IC. Additionally, the I 2 C bus  15  of the present invention has a hot-swap function such that a user can immediately swap the failed IC when it is detected.  
         [0023]     The operating principle of the management device  280  is shown in  FIG. 2  and described in the following.  FIG. 3  shows a control method of a communication system according to an embodiment of the invention. The ICs  11 ˜ 14  are inserted into the slots  241 ˜ 244 , respectively. The switch circuits  261 ˜ 265  are initially turned on.  
         [0024]     First, the management device  280  monitors the status of the I 2 C bus  15  in step  100 . If the status of the I 2 C bus  15  is normal, the ICs  11 ˜ 14  may transmit data to each other. After another period of time, the management device  280  monitors the status again.  
         [0025]     When the status of the I 2 C bus  15  is monitored as being abnormal, the communication system is determined as being blocked. The management device  280  begins to switch the switch circuits  261 ˜ 264  to locate and isolating a failed IC in step  200 .  
         [0026]     In step  210 , the management device  280  turns off all switch circuits  261 ˜ 264  for isolating the ICs  11 ˜ 14  from the I 2 C bus  15  such that the status of the I 2 C bus  15  is again normal.  
         [0027]     Following step  210 , if I 2 C bus  15  becomes normal, the management device  280  detects the first IC, and a parameter n is set to 1 in step  220 . The management device  280  turns on first switch circuit  261  in step  230  for connecting the first IC with the I 2 C bus  15 . The management device  280  monitors the status of the I 2 C bus  15  in step  240 . If the status of the I 2 C bus  15  is still normal, the management device  280  increases the parameter n in step  250  and turns on the next switch circuit in step  230 . From parameter n, the management device  280  or a system supervisor can determine which switch circuit is being switched and make record if needed.  
         [0028]     Every time when one switch circuit is turned on, the corresponding IC is connected to the I 2 C bus  15  and the management device  280  then monitors the status of the I 2 C bus  15 . If the status of the I 2 C bus  15  becomes abnormal due to the newly-added connection, the management device  280  turns off the switch circuit for isolating the corresponding IC in step  260 , in order to maintain the normal status of the I 2 C bus  15 .  
         [0029]     Finally, the management device  280  detects whether the last switch circuit has been switched in step  270 . If the last switch circuit has been switched, the management device  280  stops controlling the switch circuits and the process returns to step  100 . If the last switch circuit is not switched, the management device  280  increases the parameter n in step  250  for turning on the next switch circuit.  
         [0030]     For example, in  FIG. 2 , ICs  11 ˜ 14  are connected to the I 2 C bus  15 , a failure occurs in the IC  13 , and the status of the I 2 C bus  15  is abnormal.  
         [0031]     When the abnormal status is detected by the management device  280 , switch circuits  261 ˜ 264  are turned off causing the status of the I 2 C bus  15  to recover normal status. The management device  280  then sequentially turns on switch circuits  261 ˜ 264 . The management device  280  detects the status of the I 2 C bus  15  each time a switch circuit is turned on. When the switch circuit is turned on and the status of the I 2 C bus  15  is still normal, the management device  280  continues to turn on another switch circuit.  
         [0032]     Since the IC  13  has failed, when the management device  280  turns on the switch circuit  263 , the I 2 C bus  15  becomes abnormal and this abnormality can be detected by the management device  280 . Accordingly, the management device  280  turns off the switch circuit  263 . When the failed IC is isolated, the status of the I 2 C bus  15  must turn back to normal. After the management device  280  turns on the switch circuit  264 , data can be transmitted in the I 2 C bus  15 .  
         [0033]     In addition to the described sequential search method, the management device  280  can utilize a binary search method to select switch circuits. First, the switch circuits are divided into two groups. One group is turned off and the other is turned on. If the status of the I 2 C bus  15  is detected as normal, a failed IC in the group must be turned off. If the status of the I 2 C bus  15  is abnormal, the failed IC is in the turned on group.  
         [0034]     To allocate the failed IC, the group causing the abnormal status is further divided into two sub-groups. The management device  280  continues to detect which sub-group is causing the communication system to fail. This binary search method can narrow the detection range. Finally, when a group has only one switch circuit, the failed one is located.  
         [0035]     Advantages of embodiments of the invention are summarized in the following. First, the invention controls switch circuits and auto-detects the status of the bus such that the failed IC is located. Embodiments of the invention can shorten detection time and reduce cost by utilizing different control methods. Second, when the failed IC is located, the failed IC can be isolated from the bus, allowing the bus to again function normal. Third, since the invention auto-isolates the failed IC, a user need not remove the failed IC immediately and the bus is available.  
         [0036]     While the invention has been described by way of example and in terms of the preferred embodiments it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.