Greg - ZL3IX wrote: > I would like to hijack the scroll wheel circuit in an old mouse, so that > I can connect external devices and use them to tune the VFO in PowerSDR. > > Does anyone know how the scroll wheel circuit operates in a Logitech > mouse? I would have thought that there would simply be two optical > paths that would give quadrature drive signals, but probing around with > my scope, leads me to believe that it is much more complex than that. > There seem to be bursts of 6 us pulses regardless of whether the wheel > is being operated or not. When the wheel is operated, other pulses > appear in the gaps between the bursts. > > Does anyone know what this is all about? > > 73, Greg, ZL3IX > Greg, you are right about the internal operation of the wheel, it works the same way as the encoders found in the ball type mice. I think you are probing the output signal at the PS/2 connector, and here the things became more complex, the encoders outputs and also the pushbuttons signals are processed by a microcontroler or a custom chip which translates all of them into characters sent to a kind of serial port, if the mouse is PS/2 type or worse if it is a USB one. So you need to process your external encoder in the same fashion and connect it as a second mouse (windows can recognice more than a mouse). You probably can experiment trying to use an discarded mouse circuitry replacing its internal cheap encoder with an external one instead of emulate everything with a microcontroler.
73 de Ignacio, EB4APL _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kb.flex-radio.com/ Homepage: http://www.flex-radio.com/
