Changes
::The cpcwiki page says 1/300s, but in the forum you said 2/300s. Which one is correct? --[[User:Nocash|Nocash]] 16:04, 12 April 2010 (UTC)
::PPS. Added info on the corresponding keyboard keys, okay? I think they are good choice since they don't conflict with hotkeys, which would be more likely mapped to letters, not to 5 and 6.
Hi all, back after some relaxing Snowboarding in the alps :) Regarding the timing: Even if the COM pin stayed low all the time, the output of the 74LS240 would still permanently change if the mouse were moved. So my adapter would still react like the original AMX mouse. No idea what would happen inside the CPC though. The schematic in the Wiki is the latest version and won't be changing, the COM pin is only connected to the 74LS240, not to the PIC, the PIC is getting an almost permanent flow of information from the mouse (can't remember the exact timing, would have to check the firmware), but it was most certainly faster the the 1/300s that the CPC could manage. The only difference between the real AMX mouse and my interface is that the original AMX mouse would have had a fixed rate of pulses per millimetre (of mouse movement), which would obviously effect the "feel" of the mouse. Unfortunately I don't have a real AMX mouse to measure this, so I chose a rate that felt right. The CPC side of the interface (sample rate etc) is identical to what the AMX mouse did, so the CPC side will react just like the original.
Regarding the requirement for a pull-up resistor. If you open a standard JY-1/2 Joystick, you'll see that they also don't have a pull-up resistor, but still work perfectly with the configuration within the CPC Joy Port, my schematic is no different in this effect.
Bryce.
