James from the UK recently wrote up about his Raspberry Pi - Z80 controller project up on Hackster: https://www.hackster.io/james-fitzjohn/ ... ace-0bfbeb A few days later it popped up on H-a-D and into my RSS news feed: https://hackaday.com/2021/02/09/interfa ... pberry-pi/ Being a Z80 fan, I thought this would be a fun project to replicate, but I didn't want to bother with putting it all together on a breadboard, so I have turned it into a more permanent 10cm x 10cm 2 layer PCB - with room to spare:
and at the last moment I moved a few components from the front to backside, as I realised they where not going to fit under a 40pin ZIF socket:
In short, the idea is that you can take a Z80 machine code and use a RPi based Python program to act as host RAM for the Z80. The Python program can turn on the Z80 and present a block of code for it to read and execute. There are lots of blinky LED's to display the Z80 Data, Address and Control buses. I added a few extra RPi LED's, a buzzer and a user tactile switch.
The PCB will be sent off for production shortly to JLCPCB when people are back from their Chinese New Year holidays.
Raspberry Pi - Z80 Controller
Re: Raspberry Pi - Z80 Controller
The PCB arrived last week. Some of the parts arrived a few days later, so that allowed me to put the board together:
So, there are two PCB design errors:
1) wrong ZIF/Z80 socket used
2) I didn't include a i2C 3.3V to 5V level translation
3) while the PCB fit, and I did test a paper cut out against a RPi, it was a tight fit up against the RK45 socket
With and Z80 socket adaptor made up and a i2C voltage translation board added in, I setup a new 16GB SD card for the RPi 4 board and it all worked!
It didn't take long to add in the schematic and PCB changes:
So, there are two PCB design errors:
1) wrong ZIF/Z80 socket used
2) I didn't include a i2C 3.3V to 5V level translation
3) while the PCB fit, and I did test a paper cut out against a RPi, it was a tight fit up against the RK45 socket
With and Z80 socket adaptor made up and a i2C voltage translation board added in, I setup a new 16GB SD card for the RPi 4 board and it all worked!
It didn't take long to add in the schematic and PCB changes:
Re: Raspberry Pi - Z80 Controller
The new updated PCB arrived last week and it didn't take too long to solder up on the hotplate, here it is running a small Z80 test LED program that I wrote up:
The project files (KiCAD PCB, Code) are hosted here: https://gitlab.com/MakerinAsia/RPi-Z80_Controller
I am very happy with how this (eventually) turned out and am looking forward expanding to James's program a bit more so that the buzzer and OLED screen works.
The project files (KiCAD PCB, Code) are hosted here: https://gitlab.com/MakerinAsia/RPi-Z80_Controller