Abstract:
A wireless keyboard may be provided with a guard protocol which prevents unintended typematics. An alive signal may be periodically generated to advise a host processor-based system that the keyboard communication link is still effective. If the host processor-based system receives a key make signal but does not receive a break signal or an alive signal, the processor-based system may deduce that the link has gone inactive, and may generate its own break signal. This avoids unnecessary power consumption and unnecessary typematics.

Description:
BACKGROUND 
     This invention relates generally to processor-based systems and in particular embodiments to the use of wireless keyboards in connection with processor-based systems. 
     Wireless keyboards enable computer users to input data from positions spaced from the remainder of a processor-based system. This gives the user the additional freedom to make data entries without requiring the user to sit proximate to the processor-based system. 
     Each time the keyboard sends a wireless key make code to the host computer indicating that a key has been depressed, the host computer awaits a key break code indicating that the key has been released. If the key make code is not followed within a predetermined time frame by the break code, the operating system automatically repeats the key represented by the make code. The delay between the make code and automatic repeat is user configurable. This automatic repeat will stop when a break or another make code is received. 
     If a wireless keyboard loses its wireless link with the host computer, after sending the key make code, but before the key break code is sent, the operating system of the host computer may automatically repeat the key indefinitely. This becomes a serious problem because the keyboard may have a relatively limited effective range. If the keyboard is moved too far away from the host processor-based system, the link may be lost. Similarly, if severe interference is encountered, the link may be lost as well. 
     The phenomenon where the key is automatically repeated is called a typematic. The uncontrolled typematic that ensues can cause undesirable behavior on the processor-based system. 
     Thus there is a continuing need for ways to prevent uncontrolled typematics when using wireless keyboards. 
     SUMMARY 
     In accordance with one aspect, a method includes communicating, over a wireless link, that a key has been operated on a wireless keyboard. A wireless signal is generated from the wireless keyboard to test whether the wireless link is still working. 
     Other aspects are set forth in the accompanying detailed description and claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block depiction of one embodiment of the system according to the present invention; 
     FIG. 2 is an example of a sequence of codes that may be generated from a wireless keyboard in accordance with one embodiment, of the present invention; 
     FIG. 3 is another example of a sequence of wireless codes that may be generated from a wireless keyboard in accordance with one embodiment of the present invention; 
     FIG. 4 is a flowchart for software for implementing one embodiment of the present invention; and 
     FIG. 5 is a flow chart for software for implementing a wireless keyboard in accordance with one embodiment of the invention. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1, a processor-based system  10  may include a wireless link with a wireless base station  12  which in turn may maintain a wireless link with a wireless keyboard  14 . The base station  12  may increase the range of the wireless keyboard with respect to the processor-based system  10 . However, in some embodiments in the present invention, the wireless base station  12  may be eliminated, and the wireless keyboard  14  may communicate directly with the processor-based system  10 . 
     The processor-based system  10  may be a desktop computer, a portable computer, a handheld device, an appliance, or a set-top box, as examples. The wireless keyboard  14  may be a wireless computer keyboard, a remote control unit (RCU) which communicates with a processor-based system, which in some embodiments may be a set-top box, or other wireless peripherals such as game pad. 
     The communication between the systems  10 ,  12 , and  14  may be by conventional infrared or radio wave links as examples. In such cases, the wireless base station  12  may act, effectively, as a repeater. The wireless base station  12  may essentially receive signals from the wireless keyboard  14 , and retransmit those signals to the processor-based system  10 . 
     A processor-based system  10  may include a processor  30  coupled to an interface  32  such as a bridge or a chipset. Interface  32  may, for example, couple a system memory  34  and a bus  36 . The bus  36  in turn may be coupled to another interface  38  which may also be a bridge or part of a chipset. The interface  38  may in turn be coupled to a hard disk drive  40  or other storage medium such as a floppy drive, a compact disk drive, a digital video disk drive, a flash memory or the like. Software  16  may be stored on the hard disk drive  40  in one embodiment to the present invention. 
     The second bus  42  may be coupled to an airwave interface  44  and a basic input/output system (BIOS) storage  46 . The interface  44  receives signals from the wireless base station  12  or the wireless keyboard  14  and converts those signals into a form compatible with the processor-based system  10 . 
     The keyboard  14  may be conventional in many respects and may include a wireless interface  48  which is coupled to a key code generating controller  50 . The controller  50  in turn may be coupled to a storage  52  which may store operating protocols for the wireless keyboard  14 . Generally, the wireless keyboard  14  is battery-powered. 
     After the user activates a key in the wireless keyboard  14 , a key make code is transmitted from the wireless keyboard  14  to the wireless base station  12  to the processor-based system  10 . If after a given period of time, a key break code is not received, the operating system of the processor-based system  10  may automatically repeat the key activation as though the key were repeatedly pressed. 
     In one embodiment of the present invention, at periodic intervals, the keyboard  14  automatically generates an alive signal. The processor-based system  10  is advised by the alive signal that the wireless link is still active and that the absence of a break signal may be indicative of a typematic for automatically repeating a key actuation. 
     In another embodiment of the present invention, the alive signal is automatically produced after the make code is generated. In one such embodiment, the alive signal may be produced twice in the typematic period. The typematic period corresponds to the passage of time which is recognized as a typematic. 
     Thus, referring to FIG. 2, a key make code may be produced at time interval  0 , and an alive signal may be produced automatically by the keyboard at time intervals  1  and  2 . If the processor-based system  10  receives those alive signals, the processor-based system  10  knows that the absence of a key break code was not the result of loss of the communication link between the keyboard  14  and the system  10 . Thus, having failed to receive a break code, the host driver software automatically initiates a typematic or automatic repeat of the key activated at time interval  0 . 
     In some embodiments of the present invention, the alive signal may only be generated after a key make code has been produced. In other embodiments, the alive signal may be produced automatically in any open time period. 
     The key make code may be received by the host processor-based system  10  and then no other signals may be received for the period which corresponds to a typematic. Thus, referring to FIG. 3, in time interval  4 , a key make code is received. However, in time interval  5  and time interval  6 , no alive signal, make or break code is received. As a result of this absence of any signal, the processor-based system  10  knows that the communication link has been interrupted and automatically initiates a host generated break signal. Thus the absence of any signal is not recognized as a typematic. The user may be notified, for example by graphical user interface, that the wireless link has failed. 
     In some embodiments, the alive signal may be a packet distinguished from the make and break packet types. In this case, software may filter out these packets and use them for resetting timers. In another embodiment of the present invention, the alive packet may be a duplicate of a preceding make packet. In this case, the driver processes the alive packet as a normal make packet, but also resets the timer as described previously. 
     Referring next to FIG. 4, software  16 , in accordance with one embodiment of the invention, which may be stored on the hard disk drive  40 , begins by determining whether a make code has been received as indicated in diamond  18 . A timer is initialized as indicated in block  20 . In diamond  22 , a check determines whether the timer has timed out. The timer times out, for example, when it reaches a count that exceeds a predetermined count which may be preset by the user. If the timer has not timed out, the timer count is incremented as indicated in block  23 . When the timer finally times out, a check at diamond  24  determines whether a make or a break code was received during the timer defined period. In this case, the timer defined period may be equal to the typematic time period. If a make or break code has been received in the typematic period, the flow iterates back to the beginning and waits for the next make signal. 
     If however no make or break code was received during the typematic period, a check at diamond  26  determines whether an alive signal was received. If so, the timer may be initialized and the flow continues. If not, the host may automatically generate a key break code as indicated at block  28 . 
     Referring next to FIG. 5, software  54  which may be stored in the storage  52  begins by checking for operation of a key on the wireless keyboard as indicated in diamond  56 . When a key operation is detected, a key make code is generated (block  58 ). Next, a timer is started as indicated in block  60 . In diamond  62 , a check determines whether the key which had been operated has been released. If so, a key break code is generated as indicated in block  64  and the timer is reset as indicated in block  66 . 
     If the key was not released, as determined at diamond  62 , a check determines whether or not the timer has timed out (diamond  68 ). If not, a timer is incremented (block  70 ) and the flow recycles to again check for key release. If the timer has timed out, an alive signal is generated as indicated in block  70  and the timer is reset (block  72 ). 
     Thus, some embodiments of the present invention may reduce the energy consumption of battery-powered wireless keyboards. Since the alive packet may only be sent, in some embodiments of the present invention, while the key is pressed, and at a low rate (once every half a typematic period), the keyboard need not consume energy continuously while the key is pressed. However the keyboard enables the host processor-based system to detect a lost link in a timely manner so that undesired typematics are avoided. The alive packet may also be sent at a rate slower than half the typematic period. This will stop an undesired typematic, but only after the typematic has been initiated by a host. 
     Embodiments of the present invention may also be useful in controlling computer games which automatically repeat a gaming action when a button is not released within some game-specific interval. In addition, the present invention may be useful in connection with buttons used to emulate cursor movements via device driver software that traps the button operation and emulates a pointing device. Such software may interpret a lack of a button release within an interval as continuous motion of the cursor. 
     While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.