On Tue, 23 Jun 1998 09:20:36 +0200 Charlos Potma writes: > I am now considering using a >PC mouse, or at least some part of it as an encoder. >The standard PC mouse seems to have a DATA and CLOCK >output. Does anyone here have detailed information on the >protocol used? Sounds like a PS/2 type mouse. These use two TTL lines with bidirectional synchronous signals very similar to a keyboard. A serial mouse would be simpler to use a since it sends data one way over one wire. The data is just standard asynchronous at 1200 baud. Microchip made some pre-programmed PICs once to use as mouse controllers. The data for these had fairly good descriptions of the signal format. For a Microsoft-type serial mouse, groups of three 7-bit characters are sent LSB first with start and stop bits just like standard async data. The data is sent only after the user activates something on the mouse, if it is sitting still no data is sent. The characters are: 1(LB)(RB)(V7)(V6)(H7)(H6) - (LB, RB are 1 if the button is pressed) 0(H5)(H4)(H3)(H2)(H1)(H0) 0(V5)(V4)(V3)(V2)(V1)(V0) The PIC would look at the MSB of each character and wait until one with a 1 is found, indicating the start of a new packet. Then it could accumulate the V and H bits in proper order. I think the two 8-bit numbers are two's complement reperesentation of how far the mouse has moved since the last report. _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866]