Tuesday, 15 December 2015

Day 15 - Commodore Amiga 500 Pi2

This is day 15 of the Advent Calendar of USB keyboards. Today, an Amiga 500 USB keyboard with USB joystick ports and integrated Raspberry Pi2.
This follows on from the previous post on the Amiga 500 USB keyboard. The new board is designed to be built with different options, the main choices being for use as a USB keyboard with an external computer, or with an integrated computer.
In this case, it is built as a USB keyboard and dual USB joystick with an internal USB header, and a DC-DC converter to generate a stable 5V supply for a Raspberry Pi.
As with the other USB keyboards with integrated Raspberry Pi, I am moving to using 12V in and generating the 5V supply from that. The DC-DC is rated to supply up to 2A at 5V, it is fairly efficient so doesn't get very warm, and drawing less than 1A from a 12V supply at full load. In normal operation, it's only using about 20% of that, so lots of overhead
It is easier to find a 12V 1A supply than a 5V 2A one, and is no longer reliant on the quality of the external supply to keep the Pi happy.
The board sits in the same place, with two 9 way D connectors for the joystick ports, but this version has a 2.1mm DC jack for the 12V in. As before there is space for a mode switch if required.
The Raspberry Pi 2 is modified as usual, one dual USB port is removed and replaced with a single USB port, and the spare port is wired to a 4 pin header for the USB keyboard controller. Power in is wired directly, bypassing the microUSB connector.
This fits into one of the slots on the rear of the Amiga 500, with the HDMI extended to it's side. So in what was the parallel printer port, you have RJ45 LAN, three USB ports and next to it the old power connector has the HDMI out.
Add back the original Amiga keyboard and a USB mouse, and it's ready to go.
The Amiga emulator is not supplied with a kickstart ROM image, as that is technically still under copyright, so I read in the kickstart ROM from the damaged board.
Ready for some thorough testing. Let's go.....

Tune in tomorrow to open another window on the Advent Calendar of USB keyboards.