EZ-Retro v2, now with a PCB Apr 2017
As mentioned earlier, the EZ-Retro project could use a PCB for a more compact and robust setup. There is a nice F103 board variant (search for “STM32F103C8T6 ARM Minisystem Development Board STM32“ on eBay), with suitable headers and optional µSD on the back:
A benefit of this board, is that the schematics are also available (see the 3rd image).
So let’s create a PCB for it! All the design files are on GitHub, and here is the schematic of this new “EZ-Retro v2” design, fully dominated by that gigantic 144-pin eZ80 chip, of course:
It was quite a puzzle to get this to route on a two-layer 50x50 mm PCB, but it did fit:
And this is how it’s supposed to all fit together:
On the left are ports A and C from the eZ80 (8 I/O pins plus 3.3V/GND). Port C can also be used as serial port, including all modem control signals.
On the right of the F103 board are some spare GPIO pins connected to the F103 µC, but not all of these are free for use (the µSD card uses A4..A7, for example).
In the PCB’s top left is room for a bi-colour LED, which could come in handy during debugging.