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PC PS2 Keyboard Bus Arbitration

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roadster

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keyboard bus

I have an application where I have a point to point link with a PC at one end and Keyboard at the other. In the middle I have for arguments sake 2 black boxes they have bidirectional capabillites but no inteligence ie no micro. Does anyone know how to perform PS2 bus arbitration for such a task without putting micro's in each of the boxes as the PC keyboard is an asynchronus bi-directional device. :roll:
 

yager

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ps2 bus

Although the PS/2 is bi-directional,
but only the 'Device' side could send 'CLK',
and the 'Device' has to respond (out CLK) to 'Host'
when the 'Host' issues the Request-to-Send (RTS).
The 'Host' could drop the CLK line to set it is busy,
but the 'Device' always has to standy to serve 'Host'.
Otherwise the 'Host' will think the 'Device' is dead
when RTS is on the bus (CLK=1, DAT=0) after timeout.
As your application, you could use a CPLD/FPGA to solve,
but I don't think that it is cheap and easy than uC.
And some USB-to-PS2 has very tight timing on PS/2 bus.
FYR
 

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