Minimig PCB run - interest thread

[freqmax]

I'm interested too, but it depends on offer and price.

If the 2xRAM, FPGA, CPU is pre-assembled most of the pain is avoided.

As for size, I think a 3,5" size is the best due it fits in a drive slot both in pc-boxes and external chassi for hdd.
The only reason to go for 12x12 is that you don't need to modify the design.

I think however the design could use an onboard regulator for the +5VDC & capacitor to avoid to issues with the power supply. A 5V supply won't provide 5V after a sufficient length of wire.

As for buildin or use on-pcb-connectors. Why not replace the connectors with IDC connectors that is wired to a breakout pcb via flatcables in any manner desired ..?

[freqmax]

Belial6 wrote:
I'm kind of a fan of the ribbon cables.  It would make custom cases easier to make.  I would expect that we will see lots of  custom cases for the mini-mig.  With how small the board is, I would think that it would be trivial to make an adapter plate for anyone wanting to mount the mini-mig in a mini-atx case.  Personally, I would like to put the mini-mig into an old gutted laptop.

Maybe there is a standard for those 9pin RS232 serial connector brackets often found on pcs? ..would be really neat to be able to just plug in :-)

As for adapter any plate with a 11x11 cm square hole should allow mounting in MiniATX, problem solved. It's not problem making that hole fit a 3.5" (10,2 x 14,7 cm) either.

Is there any standard formfactor of laptop interiors?
Maybe you could just rewire the digital RGB before the resistor A/D and vsync/hsync to the builtin TFT, and let some D/A port on the MCU control the brightness and similar ..?

[freqmax]

Considering:
* We pay per square area.
* Larger boards means it will fit in less boxes.
* Dennis essentially contributed an pcb errata that needs to  be fixed.
* 3,5" drive space is just slightly larger than the 12x12cm.

Some wants to build it into specific machines and others want it standalone. IDC 2.54mm spaced pin headers, with flat cable connectors solve that.
And while at it, let those pin headers be compatible with pc IDC <-> DB9.
IDC DB9 http://pinouts.ru/SerialPorts/Serial9_pinout.shtml
CDrom<->Soundcard http://pinouts.ru/Multimedia/analog_creative_pinout.shtml

Why not modify minimig v1 with the errata and fit it into a 3,5" sized pcb (15.2 x 10.2 cm) ..?

[freqmax]

"swap pin81 and pin 79 on the FPGA. This way you still have four user-IO's left. You do need to change the .UCF file though and recompile the core."

This means non-patched and patched boards won't be compatible. Please let's at a minimum have this patch incorperated. Or we might end with two fpga binaries.. (for no good reason).

The other fixes doesn't seem to affect the plain software aspect of the board.

[freqmax]

Check with Olimex: http://www.olimex.com/pcb/index.html
Less startup costs at least.

[freqmax]

I have created a Minimig wiki:
http://www.opencircuits.com/Minimig_Project

My hope is that it will help people to accumulate knowledge in this matter such that one doesn't have to read long.. threads to find information.
Especially now that there are several.

No login required, works almost like wikipedia.

[freqmax]

ATA (IDE), ZorroII, SCSI all wants a large number of I/O pins. There a currently 4 remaining. A few more possible by reusing boot configuration pins. Getting larger fpga means BGA and that is a path you don't want to go.

But fpgas are capable of really fast communications, esp the standard spartan3. So a possibility is to use the leftover I/O to connect another fpga to hookup these things. Essentially a "south bridge" running on a pseudo serial bus.

Not minding the cost of an extra fpga, special copper trace requirements, support circuitry, power, and connectors.

[freqmax]

It would save costs possibly to connect directly. However in the eyes of an FPGA, Amiga electronics is like snails.

[freqmax]

The thing with Minimig is access to software primarly, and hardware secondarly.
PCI, SCSI can be had on any PC, Or networked to the amiga (another issue..  ;-))

Zorro could be useful for expansion cards that you simple can't run on any other hardware.
Then there's the situation with software that requires certain hardware.

I think USB might become neccessary due that keyboards & mouse  might become only available in that format. But ps/2 is a simple solution that will work for a long time. And I think the effort is better spent on other parts.
Maybe USB memories/ethernet could make it worthwhile anyway?

[freqmax]

Ok, so how much extra circuitry is needed?
Any idea how long flatcable Zorro manages?

[freqmax]

I have looked at the files. And there are some things I miss:
* Bill Of Material list (BOM) ?
* Component sourcing (where to buy) ?
* 68AW512M datasheet (need package mechanical details) ?

If the original pcb is to be used, this data is needed or a new board will have to be created.

As for production run. I think it's easiest to stick with the current one, and make the patch suggested by dennis regarding pins swap on fpga. Such that it actually get's done.
In the meantime we could tinkering with options for the next revision. And the PIC18 should be programmed with board revision such that fpga configuration for several boards can exist in the same flashcard.

[freqmax]

Do these other srams have the same mechanical package (esp pads). And same pinout?, if not we can't use the layout as is.
Might be a good idea as a minimum to provide circuits aswell as pcb board ie "kit". As to avoid not getting the parts that fit..

As for costs, I know from a fab visit that things that makes cost run away is multilayer (>2L), through hole assembly, components on both sides.
So letting end users solder connectors by themselfes might be a real cost saver (and possible time-to-delivery).

Some selftest configuration flashdisc would be really useful aswell.

[freqmax]

Looking at the dennis layout. And consider it's an 2 Layer (it is?). There seems to be no groundplane under the SRAMs, maybe adding such would benefit stability.

Hopefully we will not get an Minimig-o-Freeze

[freqmax]

@Dennis
Will digikey 428-1860-ND do?

Datasheet:
http://download.cypress.com.edgesuite.net/design_resources/datasheets/contents/cy62167dv30_8.pdf

I assumed it had to be SRAM, not SRAM-async.

Maybe it's possible to use the 2'nd layer to add groundplane?

Is the 74HC4060 wired in parallel or serial mode?
Has meaning when looking for crystals (par/ser).

[freqmax]

I have noticed that digikey.com have started to stock the XC3S400-4PQG208C at 25.45 USD for one off:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=122-1519-ND

They didn't before. So it was a real pain in the ass to get those chips at reasonable ease and price.