Raspberry Pi - Z80 Controller

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parkview
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Raspberry Pi - Z80 Controller

Post by parkview » Sat Feb 13, 2021 4:38 pm

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:
Raspberry Pi - Z80 Controller V0.5 PCB Front_sml.jpg
Raspberry Pi - Z80 Controller V0.5 PCB Front_sml.jpg (70.4 KiB) Viewed 537 times

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:
Raspberry Pi - Z80 Controller V0.5 PCB Back_sml.jpg
Raspberry Pi - Z80 Controller V0.5 PCB Back_sml.jpg (52.58 KiB) Viewed 537 times

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.

parkview
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Posts: 522
Joined: Tue Jun 24, 2014 8:25 pm
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Re: Raspberry Pi - Z80 Controller

Post by parkview » Sat Mar 20, 2021 4:44 pm

The PCB arrived last week. Some of the parts arrived a few days later, so that allowed me to put the board together:
Z80-running2.jpg
Z80-running2.jpg (245.43 KiB) Viewed 517 times

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!
RPi-Z80 controller running.jpg
RPi-Z80 controller running.jpg (108.46 KiB) Viewed 517 times

It didn't take long to add in the schematic and PCB changes:
RPi-Z80 Controller V1.0.jpg
RPi-Z80 Controller V1.0.jpg (148.42 KiB) Viewed 517 times

parkview
Guru Maker
Posts: 522
Joined: Tue Jun 24, 2014 8:25 pm
Location: Busselton
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Re: Raspberry Pi - Z80 Controller

Post by parkview » Wed May 12, 2021 10:59 pm

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:
RPi-Z80.jpg
RPi-Z80.jpg (63.83 KiB) Viewed 426 times
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

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