A3000 IC2 - keyboard/mouse controller

Arc/RPCs, peripherals, RISCOS operating system & ARM kit eg GP2x, BeagleBoard
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myelin
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A3000 IC2 - keyboard/mouse controller

Post by myelin » Thu Oct 11, 2018 10:59 pm

Hi all,

I've just come into possession of a few sparingly-populated A3000 boards, two of which are missing IC2, the keyboard/mouse controller. I wonder if anybody here has made a modern replacement for this chip?

It looks like it talks to the rest of the system via a two-wire asynchronous serial interface that connects to the KART block in the IOC, and runs at 31250 Hz (based on the logic in the IOC datasheet and observing in Arculator that RISC OS 3.11 writes 1 to the timer 3 latch register), so it should be quite reasonable to hook a microcontroller in there. Handling modern USB keyboards and mice would be complicated by the need to provide two USB ports, but I guess a pair of $1 ATSAMD21E15 chips could take care of it.

Does such a thing already exist, or is it something to add to the to-do list?
Last edited by myelin on Thu Oct 11, 2018 11:04 pm, edited 1 time in total.
SW/EE from New Zealand, now in Mountain View, CA, making BBC/Electron hardware projects for fun.
Most popular: fast serial port, FX2+PiTubeDirect Tube/Cartridge adapter, USB cart interface.

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IanS
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Re: A3000 IC2 - keyboard/mouse controller

Post by IanS » Thu Oct 11, 2018 11:50 pm

The two wire serial interface is the same as the usual keyboard connector on the A3xx/A4xx etc. machines. So you can, if you have one, use a normal Archimedes keyboard. Flip link 16 and wire a din connector onto LK3.

You can then also use one of these - viewtopic.php?f=16&t=9334

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myelin
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Re: A3000 IC2 - keyboard/mouse controller

Post by myelin » Fri Oct 12, 2018 5:18 pm

Ahhh, that makes a lot of sense, and explains what LK3 is for. I'd actually spotted that project by IanB but hadn't realized that it was a PS2-to-KART protocol converter :)
SW/EE from New Zealand, now in Mountain View, CA, making BBC/Electron hardware projects for fun.
Most popular: fast serial port, FX2+PiTubeDirect Tube/Cartridge adapter, USB cart interface.

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IanB
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Re: A3000 IC2 - keyboard/mouse controller

Post by IanB » Sun Oct 14, 2018 12:51 am

myelin wrote:
Fri Oct 12, 2018 5:18 pm
Ahhh, that makes a lot of sense, and explains what LK3 is for. I'd actually spotted that project by IanB but hadn't realized that it was a PS2-to-KART protocol converter :)
Although it's a PS/2 converter, I primarily made it for use with Aten CS1734B & CS1732B KVM switchboxes.
These KVMs take USB keyboards and mice (including wireless mice receivers) and can do internal USB to PS/2 conversion although you have to buy the optional PS/2 multiway cables to connect to PS/2 systems as only USB cables come as standard.
At the time a direct USB solution wasn't really feasible but as I had multiple Acorn systems and needed to use a KVM anyway, these Aten KVMs were the ideal solution to getting USB keyboards and mice working.

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