Retromaster’s Electronics Projects

…related to old computers and other assorted stuff…

UFE A500 Keyboard Daughterboard

Posted by retromaster on June 7, 2010

Over the weekend, I built the A500 keyboard controller daughterboard and got it to work with UFE.

The operation is quite similar to the TFE+ board. The daughterboard sits in between the A500 host and the keyboard, listening for key events. Once it detects the UFE activation key combination, it starts to prevent the host from receiving the key events and redirects them to UFE instead. When the user is done modifying UFE settings, the daughterboard is signalled to stop redirection of keyboard events and the host becomes able to receive keyboard events again.

The daughterboard contains an 14-pin PIC24F04KA200 and it communicates with the PIC32MX on the UFE board via the I2C protocol. Currently I2C slave reads are implemented, but the slave writes are missing (so UFE is unable to reactivate the host keyboard event reception). I should be able to implement this soon.

Normally, the daughterboard is intended to be plugged right into the keyboard port on the A500. Unfortunately, I’ve made a couple of mistakes with the board schematics/layout. I’ve confused the keyboard input and output ports and I’ve made another oversight regarding the keyboard data line that I’ve had to fix with a couple of jumper wires. So, I’ll fix these issues and soon make a new PCB.


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