Matthias has mouse-supporting routines & infos. Check about 1/2 way down the page: M D GAMES.
His next release will support it
I may be wrong but as far as I can see that method relies on the mouse outputs basically being two, 2 bit grey codes simlar to the rotary controllers (although they only use one) which is how older wheel mice worked. My understaning of modern optical (and particullay USB) mice is that they output 3 or 4 bytes of data depending on if it has a wheel button thingy or not so I don't think it is that simple.
I do however think the way modern mice output data is better for the Jag as it is scalable so programmers can multiply/devide the values to get the speed they want or even let users calibrate it to speed they prefer and save the scaling value to the cart, additionally that type of output lends it self more easily to the Bank Switching advanded controller type that Atari have mice listed as in the TechRef.
sh3 : if you use my firmware, DPI won't be a problem ; it limits the pulse rate to the maximum the ST keyboard processor can accept (I think it's 2000 pulses/second, but it's been a while, I'd have to check.). It can be changed if necessary.
I am quite prepaired to be proved wrong on this but don't modern optical mice basically take two images, compare them to work out how far the mouse has moved between images. If so then it may not be necessary to read the mouse at the rate it can sample the amount of movement, provided the byte values are internally updated regardless of if they are read or not you will always read a movement value out if the mouse if it is moveing. The fact that you only read say one in every 10 samples it is capable of outputting may not be an issue as...
1) The revieved value is scalable as I mentioned before so that can be compensated for
2) Concidering the resolution of the typical Jaguar game screen is about a quarter of that of a modern PC screen you I doubt you would need the same dergee of accuracy and there need less samples per second otherwise a small movement of the mouse would send the cursor right across the screen.
But I have not had time to look into a Jaguar mouse fully (it is on my to do list) so I am largely speculating at this point.
Here is why i never came up with (--> released ) a PS/2-mouse adapter or something integrated as you plan:
Atari says that the joyports are only good for 50mA, at the timeframe i looked into the topic the majority of ball-mice and all of the optical mice needed more than 50mA so it would have been necessary to add a secure power supply to the adapter.
That's true, but I think Atari was conservative with the 50 mA specification ; the +5 volt pin on the pads connectors is connected directly to the main power supply through an inductor. Assuming you don't have anything else connected to the other pad port, drawing 100 mA from a single pad port should probably be OK.
Anyways, most optical mice tend to require 100 mA, but I've seen a lot of ball mice which require less than 50 mA.
By the way, I'm working on a simple PS/2 adapter right now
I have done some testing on my Jag and I have to agree with current limits Atari place on the Jaguar I/O ports, if you absolutely have no other option you could go are far as 100mA per controller port but that is an absolute never to be exceeded value
The one issue I have with anyone doing that espically for a single controller is that someone who may not be aware that it is taking that much current may later decide to write an 4 or 8 player game for that controller resulting in your Jag going up in smoke as you try and suck 400mA from each controller port as not everyone would think/be prepaired to buy 8 controllers to fully test it and thus blow up thier Jag first.
My advice to controller developers (for what it is worth) would be to stick with the 50mA per controller Port limit (12mA/Controller to allow for 4 players) but if exceeding that it can not be avioded do not exceed 100mA per controller port (24mA/Controller to allow for 4 players)
and preferably provide your hardware with its own power supply.