matze79 wrote:
Its version with bootloader support, mouse will powered up after bootloader, so there is a small time window for firmware upgrade over rs232.
also added crystal for more stability.
Did you get the DOS software working? Need help with it? Or is it an issue if you can upgrade with a modern PC (and USB serial port for example)?
matze79 wrote:You already added a fix: (not included in simons ZIP, you should apply youre right, it really could destroy a mouse, kits i send […]
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You already added a fix: (not included in simons ZIP, you should apply youre right, it really could destroy a mouse, kits i send out already fixed this.)
void ps2_gohi(int pin) //gohi and golo were tested working fine.
{
pinMode(pin, INPUT);
digitalWrite(pin, HIGH);
}
That looks good. I don't know if it was intentional, but the clock and data wires on your schematic have no pull-up resistors, but that code does turns on the AVR built-in weak pull-ups (when direction is input, and data is high). I think some incompatibilities with some mice or KVM switches could be solved by real pull-up resistors, I think 10k is used on host side and 2k on the device side but something around there should work.
I suggest you consider also the transistor a bit. In a KVM situation that routes a VGA monitor and PS2 mouse, most likely the KVM connects the VGA ground to PS2 ground internally, so even if the transistor is turned off, both sides of it are already at ground potential, and any current flowing on PS2 cable from your adapter to KVM, the return path for the current is through VGA cable. But for a direct mouse connection, it looks it's handy to reset the mouse by turning the power off.
And with the 1k base resistor, it may or may not turn the transistor on hard enough, so it's possible that there is too much voltage drop for some mice, at least for those that consume a fair amount of current (say, over 100mA). Fortunately this is easy to measure with a multimeter, try it 😀 Some KVMs might also try to power from PS2 5V supply.
matze79 wrote:
I'm almost happy with it, i never thinked i get it this far. i'm not a electric engineer 😀
Well in that case, I think that is pretty impressive. You have many details done the way they should be done 😀