Interest check: An updated MiniITX-MiniMig ( Pics!!! )

[alexh]

yaqube wrote:
@alexh
It has 256KB Flash ROM and 64KB RAM on chip. It's not an overkill, it's a simple and small MCU with ARM7TDMI core.

Which is almost 3x the price of the device it is replacing. I wonder what that does to the overall retail price of MiniMig? (Which was already very high).

How much does it cost? [Edit: ~$11]
How much was the PIC? [Edit: ~$4]

But if you could reduce the cost equally by switching to SDRAM you might be able to bring it back in line.

@55MHz it would have considerably more power than MiniMig :-)

[trekiej]

I would like to see MITX-MM have more than the original Mini-Mig. What do you think would make it more mature?

Making it fit into an ATX media case sounds good to me.
Could connecting it to a Beagle board be good?

[CD32Freak]

Great board improvement ideas! Count me in, I'm interested :-)

[freqmax]

@yaqube:
Less complex components, less cost, less soldering mayham. So if the present MCU (PIC) can't handle FAT16 then we might create a small MCU with large memory inside the FPGA that does handle the non-boot stuff.
Btw, I definitly like your switch to DRAM, hopefully it's bugfree too
(DRAM is tricky)  

The SDRAM pinout might differ. But then you can also totally reconfigure the i/o pins to accomplish the new task. And thus wire the SDRAM to the pcb pads for the SRAM.

@Illuwatar:
Do you think it's possible to shrink the actually used area on the pcb such that any would-be-laptop-hackers can cut the board into a smaller form factor to fit a mini laptop. While still keeping the Mini-ITX formfactor.
Using same pcb for both users = less costs.
But I guess the board is as compact as it's possible to make it.

[Illuwatar]

Lot of good ideas, but many of them breaks the compatibility with the original design. And there is already an other designer working with a "Super MiniMig", doing a lot of the things you want:

http://www.amiga.org/forums/showthread.php?t=35270

My idea is more to make a solution that takes Dennis original design and make it more user friendly by changing physical aspects of the PCB and adding a few features.

That ARM-plugin board sounds interesting. I maybe should change back to the PIC18LF252 to make my board compatible with that extension.

Going smaller is possible - look at the on-going project Mini-MiniMig at my homepage. But to do that, a 4-layer design was required. The MiniITX is 2-layer, making it harder to shrink it to a decent size. Also, going smaller means getting rid of the connectors and replace them with pin headers. The MiniITX will fit fine in a standard PC-case - that's the whole idea of this project.

[freqmax]

In that case just do the hardware bugs errata. But I think the ARM CPU will just increase the cost in the end. FAT16 handling can be done with an FPGA softcore MCU.

[Illuwatar]

All buggfixes are now implemented in the schematics. Still some connector issues to solve to be able to put all connectors at the rear. This correction release will spawn an entirely new PCB layout. By moving all the connectors, I have to basically re-route the entire board. That is actually good as I can optimize the design even more, specially the power supply will go through a rather serious change. I will also add this header/connector that allows access to the RGB-ports at the FPGA (for direct LCD/TFT connection).

For the PIC, I will make it possible to use both the 252 and the 452 (not at the same time of course). This will make the board really 100% Dennis-compatible (with the 252) or you can go for the larger PIC and have a few more port for fun. With this solution, this ARM-expansion will fit my board too (not just the Dennis original one).

[yaqube]

@Illuwatar

I can provide you with the outline of my adapter board and its component locations so you will be able to optimize component placement of your board (mechanical constraints).

What file format is suitable for you: Gerber, DWG, DXF?

[freqmax]

I would bet on Gerber

[Illuwatar]

yaqube - that would be nice. You could send both file formats, but the AutoCAD version would be preferred in case you have to select.

[Illuwatar]

Update:

Got the drawing of the ARM-board from yaqube - many thanks!

The PCB-design have been started, currently laying out the parts in a more optimized way than before. It will be an entirely new board as none of the old layout will be re-used. And I managed to put all connectors where they belong: at the rear face of the PCB.

[trekiej]

How long do you think it will take to redesign the board?
Thanks again.

[denli]

(Bump)

[Illuwatar]

The project is ongoing, it just takes some time as I have to split the time with other things. The board is routed to about 90% (I do it entirely by hand).

[trekiej]

One piece of software that I have seen is FreePCB.
The author made his own net lists by hand. He used two high lighters and got good results.

[Illuwatar]

Board is 100% routed and it passes the DRC-testing... :-D

What left to do are some minor tweaking of the ground planes, then they are done for manufacturing.

Before actually making any boards, I need to get some sense of interest. A few have indicated that they will buy boards, but should I make 10, 25 or maybe more? Total cost will of course increase for each board added but the price per unit will decrease. Before shelling out for a 25-board run, I must be sure to sell them all (except for a few I keep for my own joy). Calculated prices based on board size and manufacturing parameters are: €25/each @ 10 boards, €14/each @ 25 boards. This price includes shipping from China to me but not from me to You. Also, there are zero-profit prices - the job is done for free if I sell for these prices. I'm unsure what is fair to take as a "reward" for the work making these boards - the Amiga-scene is little bit like a family...

Maybe the first run should be like five boards or so to prevent a large economical damage in case of board errors found during testing. If the board runs fine, I can do a second order. One thing i sure - I'm not going to sell any untested designs.

Edit: What color should i choose? Keep the flat black or select something else... :-D