Mini-ITX MiniMig

Disclaimer: With that said and done, time to get into the build itself. First of all, to understand the function of the Minimig itself, go to Dennis homepage and read through the description. My design uses the same core as the original Minimig, but I did change or add to the periferial parts. What I have done are as follows: This project is ongoing and far from finished. There are several problems that have to be solved before the board plays any games. My first issue was the PIC-programming at 3.3 V supply. Some dirty tricks and a bootloader will save this first run, but it needs to be improved for an updated version (either by allowing the PIC to run at 5 V or by swapping it out for an ATmega instead). A part of this is of course to get the firmware to run at a different PIC. The PIC18LF252 and PIC18L452 are partly identical, so it should not be a big issue, if I only can program it...

The next thing is to figure out how to create a proper core-file for the FPGA. The actual syntesising-procedure isn't a problem, but to find out what PROM-format to use is. There are some to choose from.

2007-10-08: Completed the Parallel Cable III and was able to contact the FPGA with the iMPACT software. At least, I know that the FPGA is alive and seems to work (all voltages are at correct places). Program download will be tested when the PIC-section is up and running. A proper compiled bin-file for the FPGA is avaiable at Dennis homepage (useful for any Minimig-builder out there).

2007-10-12: Finally got the bootloader to work. A grounding error at the PCB caused a few days of fault locating USART-code for PIC as the bootloader was not working. Also, the PCB symbols for the DSUB-9 connectors from Protel are mirrored, so these has to be changed before making a new board layout.

2007-10-13: More progress - this time the OSD-menu showed up. Still no sign of an Amiga boot yet, so there are some debugging to do. At least I know that the video converter is working (I got both composite and S-video out) and the keyboard is usable. Also, the PIC reads the SD-card (a 512 MB Sandisk).

2007-10-14: Finally, the board is working! The problem with the non-booting Amiga was when I found it, simple. It seems like the Minimig requires 512 kb Kick-ROM. A 256 kb Kick did not work (even if it works in WinUAE). When a proper ROM was loaded on the card, it just started up and showed me the classical 1.3 floppy hand.

2008-08-25: A new PCB design is in progress. Due to requests, I'm re-designing the layout of the board and in the same moment I will correct some faults in the original design. The most noticable changes are the connectors that will be moved to the rear end of the board, making it a true Mini-ITX.

2008-10-26: The new design is completed - the Version 2.0 of the Mini-ITX MiniMig is born and official. It got its own project page, go there and see what has been changed and what is new.

What next? The board is now working and I can both play games and amaze the world. But it will not end here. First, I have to finish off the boards that I have in store. A friend of mine will almost die for one... But the development will not stop. I have to correct the errors that I found in the PCB layout. Then, I will replace the VGA with component outputs. The reason for this is simple: 50Hz (PAL) VGA does not work on most of the PC flatscreens. But component port may take it and the board could be switched over to 15kHz RGB that really works on any modern TV-set. The composite and S-video ports will be kept as they just works fine. I will also modify the PIC-section to work better with ICSP. As it is now, thers is a single chance to get a correct bootloader in. If it fails, Your board are screwed. But with some minor additional logic, this could be solved. Regarding the switchregulators, I maybe will swap them out for low-drop linear ones, just to eliminate the risk of interference from the switching frequency.

At the software side, there will be more possibilities. But to explore them, I need to learn more about PIC-processorns and FPGA programming in Verilog.

And there are the mechanical pieces too - it needs a nice case of course. So, this project is far from completed. It has just started something new, thanks to the amazing work from Dennis (keep it up) and some really busy weeks for me. ;-)

Stay tuned...

Project Files:
Web-links related to this project:

The 0-series bare PCB, made by PCBCart in China. Very good quality for decent prices.

PCB Detail.

An almost complete board.

Finally, it booted up! The classical 1.3 floppy hand screen...

AmigaDOS 1.3, just before some game started

Turrican, a real classic...

In-game shot. Yes, it works nice and plays like the real thing

Giana Sisters - a good test for emulators (it often fails of some reason)

In-game here too. Same feeling as it was my old A500...

The workplace where things are born...

Close-up of the setting. Luckilly, I have saved my old Red-Ball joystick...