FPGA Video card - Version 2.0
While I have already designed a working but minimal FPGA based VGA graphics card based on the Spartan-6 FPGA, I have already designed a follow up design for ...
Archives
2022
DdraigDOS: The early(ish) days
DdraigDOS was born out of a desire to have a proper operating system for Y Ddraig. Initial testing to get the basics of the hardware was done using some basi...
Joypad, V9958 and V9990 Video cards
While I haven’t updated this site in quite a while, I have been making progress on a few different areas of Y Ddraig. On the hardware front, I have finished...
2021
Expansion card: YM2151 Audio
This sound card is based around the Yamaha YM2151 8 channel FM synthesiser. It was used in some Yamaha synthesisers and systems such as the Sharp X68000 and ...
Expansion card: TMS9918A
When I ordered the new PCB for Y Ddraig, I also ordered some additional expansion card PCBs. A couple of these I had made previously and just moved the desig...
New PCB for Y Ddraig
One of the things that I have been working on is a new circuit board design for Y Ddraig. Superficially the board design is much like the previous revision. ...
FPGA Video card update
I’ve been working on several areas on Y Ddraig the last couple of months and I have been making some good progress. I’ll be posting some updates on some of t...
FPGA Video card CPU access
In my previous post, I had the VGA output working and was able to display several test patterns. I briefly mentioned that I could read data from the SRAM on ...
FPGA Video card testing
The FPGA video card has been built up. A couple of mistakes in ordering the parts so I ended up with a couple of capacitors that have the wrong footprint but...
FPGA Video card
Now that I have two expansion boards working successfully with Y Ddraig, a sound board based on the Yamaha YM2151 and a video board based on the Yamaha V9958...
Working board and audio
Bringing up the new board this time was pleasantly straight forward. I did have one mistake on the design where the enable lines for the data bus buffers we...
Y Ddraig redesign
It has been quite a while since I have posted any updated here. Some of the lack of progress was down to working from home. While I thought that this would g...
2020
SN76489: Success and Failure
Trying to get the SN76489 working has been an interesting exercise and a good example of why it is important to read datasheet with great care. Initially I ...
A small update
It’s been a while since I’ve done any work on this project. I was going to build, or at least part build a second board to see if I could get the V9990 worki...
2019
DRAM and IDE
The last couple of weeks have mostly been spent working on improving the monitor code but there has been some progress on the hardware side as well. Both th...
YM2151 Sound
Getting the sound working turned out to be easier than expected and managed to get the YM2151 playing music fairly quickly. To get some music playing I used...
Monitor ROM
Y Ddraig now has a ROM based monitor program to speed up development and debugging. It’s based on the zBug monitor by Wichit Sirichote. The ability to...
It’s Alive
A working serial port! Tracking down the problem Fixing this involved a bit of head-scratching when trying to track down the problem. All logic signa...
First Software
With the hardware assembled and the CPLD programmed it’s time to start writing some code to test and see if the hardware is working. The first program to te...
Address decoding
Before writing any software for Y Ddraig the CPLD will need to be programmed. The CPLD being used here is a Xilinx XC95108 and it is responsible for the addr...
PCB Populated
It’s been a while since any updates but some progress has been made. I’ve populated one of the PCBs and powered up the board. All seems fine so the next step...
PCBs delivered
I have recieved the new PCBs. Ordered from https://jlcpcb.com/. Initial inspection shows the boards seem to be fine. Next step now is to start building up o...
PCB design re-started
After a long break from the project I have decided to restart the design making a few changes to the board.
2017
Problems with the PCBs
Started to assemble the first circuit board and run into some immediate problems. It turns out that there is a short circuit between the 5V and GND planes on...
PCB design completed
The schematic design has been done and after many hours routing tracks the PCB layout has been completed and ready to be sent off for manufacture. ...