elfoam/a1200_keyb_mpu

Amiga 1200 keyboard MPU drop-in replacement pcb

A1200_keyb_MPU

Amiga 1200 keyboard MPU drop-in replacement pcb

As the 68HC05 (p/n 391508-01) used in the Amiga 1200 is getting to be very expensive, I designed a drop-in replacement pcb using Atmel (Microchip) MPU - ATMEGA324PB-20MU.

Advantages:

• No crystal required
• No Voltage monitor IC required
• SW can be updated to support an external keyboard with other protocol. Connected e.g. to the unsoldered crystal's pins.

How it looks:

Firmware:

Designed with "IAR EW for Microchip AVR 7.30".

To download the hex code an STK500 can be used with avrdude tool. A batch file for avrdude is included in "firmware\release\exe" folder as well as in "\debug\exe"). STK500 to the pcb connection is shown below:

PCB:

To fit the MPU's footprint it shall be made with "castellated holes" technology, which is expensive. So I made a simple board with normal holes. This board needs to be cutted to fit the footprint as shown below.

Both gerber files included in the "PCB" folder:

1. A1200_keyb_mpu_olm_normal_Gerber.zip - Normal pcb, to be trimmed.
2. A1200_keyb_mpu_olm_cast_holes_Gerber.zip - Ready to be produced with "castellated holes" technology.

The pcb is not compatible with a PLCC socket. Must be soldered to Amiga's pcb.