Minimig PCB run - interest thread

[pixie]

No pain, no game... ;-)

[amiga_3k]

I'd say: Produce it as it is now. Forget about USB / IDE for the moment. The compact-flash implementation in place right now should be enough to 'act' as a harddrive. The cards have sufficient capacity and cost next to nothing (said that, the bytes/euro is way smaller than with IDE harddrive but hey, who needs 200GB of storage on a OCS/ECS Amiga?). If there really is a need for IDE/USB solutions will surface soon enough.

And I too like the idea to raise the PCB price a few euros and donate those euros at Dennis' bank-account. He deserves it.

[Aegis]

If I can stick one in a Shuttle case (mini-ITX) then I'll have one, fully assembled - thanks! What a great project!

[Jope]

A600/A1200 IDE would be really easy to add here, it is after all mostly an address decoder and the drives hang off the bus.. Perhaps one surplus IO pin for the drive select.. I can't remember what else you need.

Then just load an A500/600/2000 ROM.

If it can be incorporated to the new board, please do it.

Probably wouldn't even be a cross-incompatible fork of the core.

[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.

[AJCopland]

I'd be perfectly happy with the released board design, one unpopulated and one populated, no alterations required.

If you do go making alteration then I guess I'll have to see but I wouldn't object to IDE, a faster 68k or more ram :-D

andy

[jkonstan]

68AW512M ,an ST 512Kx16 SRAM in a 44 pin TSSOPII package, is no longer produced. We will have to substitue a Cypress (CY62157EV30LL-45ZSXI), ISSI (IS62WV51216BLL-55TI), or Renesas (HM62V16514LTTI-5) SRAM.

 :-)

[TheMagicM]

I agree on the 'ignore the other stuff for now, like usb, ide, floppy'.. that can wait.  change the mobo design and build it as is, it'll get the job done.

[odin]

Put me down for one as a DIY-kit, just the PCB with the SMD stuff in place would be cool.

[asapet]

I'm up for one assembled, case or no case. Price is irrelevant.

Cheers!

[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.

[jkonstan]

All of these SRAM parts below (55nsec or faster) share a common pinout and TSSOPII footprint:

68AW512M ,an ST 512Kx16 SRAM in a 44 pin TSSOPII package

Cypress (CY62157EV30LL-45ZSXI) 512Kx16 SRAM in a 44 pin TSSOPII package

ISSI (IS62WV51216BLL-55TI) 512Kx16 SRAM in a 44 pin TSSOPII package

Renesas (HM62V16514LTTI-5) 512Kx16 SRAM in a 44 pin TSSOPII package

What could be different and may cause an issue between these SRAM parts is ground/VCC bounce since the PCB is only 2layer and lends itself to a higher inductive volatge drop Ldi/dt on the power and ground connections to the ICs. We can only tell this by testing some of these SRAM parts in an actual 2layer MiniMig PCB.


 :-)

[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

[gnyx]

interested.
clockport?

[Mikkel]

I believe there was some talk about using a 1Mx16 RAM earlier in this thread, as that would be much cheaper.

[Dennis]

What could be different and may cause an issue between these SRAM parts is ground/VCC bounce since the PCB is only 2layer and lends itself to a higher inductive volatge drop Ldi/dt on the power and ground connections to the ICs. We can only tell this by testing some of these SRAM parts in an actual 2layer MiniMig PCB.

That can be a problem. On the current board I have had none of such problems however. A friend of mine used to pause Lemmings the whole night and the board was still running every morning. The ground path from RAM to FPGA is pretty wide so inductance is probably not too bad. A single ram chip would be even better though, as no signal routing is necessary on the ground plane.

Dennis