Minimig PCB run - interest thread

[Troika]

 

The other problem is parts, some can only be purchased in large quantities. The SRAM appears to be obsolete, which is an even bigger problem.

:idea: Rochester Electronics http://www.rocelec.com/

They used to buy up new old stock of obsolete parts.  Not sure with Rohs, how their business is?  :-?

[Troika]

count me in, 1-2 boards, assembled or not

Is a list around to sign up?   I'll go for 2 boards assembled.

[jkonstan]

Thanks for the schematic.

The UB & LB strobes on the SRAM are due to data bus addressing needed for the 68K cpu. 68K CPU has UDS* strobe for upper byte lane D15-D8 access, and 68K CPU has LDS* strobe for lower byte lane D7-D0 access. When 68K does a read, D15-D0 can be accessed as a word with 68K reading what it requires off of its Databus; however, a write access on a 68K CPU requires the byte lane be qualified. When UDS* active on a write cycle, UB* on SRAM must be active. When LDS* active on a write cycle, LB* on SRAM must be active.  

D15 ........D8,,,,,,,,,D7........D0
Byte 0= Even,,,,,,,,Byte 1= Odd   =>  (Word 0)          
/UDS ,,,,,,,,,,,,,,,,,,,/LDS    

etc ....



 :-)

[freqmax]

What a mess :-)
Any idea how to make the fpga translate it into plain 16bit access? Or even 32bit.. as any sdram is likely to be organised that way.
I think the catch here is partial write where one could need to first read 16-bit (or32), modify, and then write back. Meaning the ram would have the double access time in practice.

Regarding the schematic. The most needed is the .inc files for the parts. Particulary the sd-card socket seems to be a pain (an image -> .inc program would be nice). At least the supplied would do for a hacker setup by having a ll signal solder pads done. Maybe should use a digikey.com one instead?

A clarification of the various component packages used would be useful.
The LM1117MP-adj for example is likely to be SOT23 asfair, because that's the only pkg size digikey have in stock in one-off quantities.

[trekiej]

Is there an official place to sign up?
Thanks.

[amigadave]

basman74 wrote:

amigadave wrote:
Has anyone calculated what all the parts to produce a completed Minimig should add up to, minus the PCB itself?

For 100 off, My guess would be like this (prices are in USD) most prices were obtained from Digikey:

Per unit cost - Minimig Rev. 1.0

FPGA:          $19.25
PIC:            $5.15
PCB:            $7.00
2 x SRAM:      $14.50
68k CPU:       $11.00
misc IC's:      $1.80
MMC slot:       $2.20
Connectors:     $5.50
Headers:        $0.50
Passive parts:  $4.00
--------------------
Bare PCB:       $7.00
--------------------
parts delivery: $3.00
--------------------
Subtotal:      $80.90
--------------------
Assembly:      $25.00(hand assembled?)
--------------------
Unit cost:    $105.90
 
Deduct $32.00 from the above to give you your answer for parts cost minus PCB and assembly.

Cheers,

Valentin

PS: Using the 'Toner transfer' method to make the PCB would prove challenging, given the presence of the PQFP

Thanks Valentin,

I have reconsidered and will wait until someone (maybe you) produces fully assembled boards to purchase and complete the rest of the project to have my own Minimig.

Unlike some others here, I only want it to run games on in the smallest form factor possible.  If it could be fit into the base of a joystick that would be ideal.

I don't see the point of making it with PCI, USB, etc. extra connectors and 68030 or faster capabilities.  The majority of Amiga games will run on the 68000 w/1mb RAM.

I would like someone to take Dennis' work and expand on it to make a better Amiga in the future, but that is a completely different project that will take considerably more work.  When it has progressed to a point which exceeds my current 68060/50mHz & 604e PPC/233mHz Amiga I will buy that project too, but I think that is a year or three off into the future.  Someone, or some group of geniuses here please prove me wrong.

For now all I would want is Dennis' original concept, with his suggested fixes, produced in the smallest package to fit into the base of a joystick, or if not possible, perhaps into an old 1010 external floppy drive case.

Lots of interest here, let's get this done before Christmas so we can all enjoy the fruits of our labor putting a Minimig together.
 :-D

[Belial6]

@amigadave

I think you hit the nail on the head.  If the first run waits for improvements, we will be another two years out.  Our best bet is to do the simple modifications that Dennis has already suggested, and get it out as is.

Slap a MiniMig 1k sticker on it, and THEN start talking about all of the cool additions that could be made for future models.  The MiniMig 1/2k could be for those of us that want a small form factor, and are not concerned about upgrades, while the MiniMig 2k could be the larger form factor with expansion ports.

What is needed now is working MiniMig 1ks that people can start playing with, and can find the limitations, so the second run can be better.

Maybe the real question shouldn't be, who would be interested in a MiniMig, but

Who would be interested in spending $150 now on a MiniMig 1k, knowing that there will be a better model available a year from now?

I definitly am.  I have no problem spending a $150 today, so that production gets started.  After all, no matter how much talking is done before the first run, as soon as the units are in our hands, people will start finding things that could have been done better.  That is what future models are for.

[ptek]

I may be interested on a fully assembled (or at least with the tiny SMD soldered) depending on price.

[Mikkel]

About the SRAM: No, it isn't 22$ totally, no we don't need to look for expensive, obsolete RAM chips of the same type that Dennis originally used. The chips I linked to earlier are 1Mx16, so we only need one. This will also simplify the board layout. This should not be any problematic, as this chip was originally suggested by Dennis a bit earlier in this thread.

[Dennis]

After reading this thread, I think it's best to just keep the first "batch" of Minimig's simple and plain, so no PCI, no USB  etc. The Minimig is already complex enough in it's current form and if we get the hang with the rev1.0, we can move to rev2.x. That board can be mini-itx with larger fpga, usb, sdram, compactflash-harddisk... but I would stay away from PCI slots and ram slots. SDRAM is so cheap nowadays you can just solder 32mbytes onto the board for a couple of dollars. Saves the hassle of making the board compatible with any brand of ram sticks out there. Also, who needs PCI if you can code your own graphics card into the FPGA?? Just a simple framebuffer would suffice to create an 800*600 16bit color desktop. Switching the monitor from rtg to ocs? Just a couple of lines of verilog. Coupled with a 20Mhz 68000 or even a 68020 it would be very nice and still simple to build, maybe even on 2 layers.

So, my proposition is that the minor revisions be all core/firmware compatible (so rev1.1 would have the bugs fixed but still be 100% compatible with 1.0) and 2.0 will have different fpga, different ram etc. If we keep the verilog code modulair, we can build cores from the same source tree for both rev1.x and rev2.x boards. If you look at the code now, only minimig1.v and minimig1.ucf are board specific, all other sources could be re-used for a rev2.0 board.

Dennis

[freqmax]

I agree SDram is cheap enough that they are a bargain path for memory upgrade. Provided that we can figure out a sdram "driver" in verilog. Loot those evil x86 pc's :-D

As for compability. It would save some headache if boards can use the same fpga configuration binary. And in the case they can't the MCU (pic18) should select the appropiate one based on board revision.

A cheap upgrade path is to have unpopulated areas where one could add chips for sdram, composite output etc..

[Belial6]

Dennis,

Thanks for giving your input here.  There are a lot of dreams, and desires on what the MiniMig should and could be.  People have been waiting to have an Amiga compatible for a long time, and you have made it possible.

Because you have single handedly raised the dead, you by default have become the Amiga's second coming.  This means your word concerning all things MiniMig are going to be taken largely without question.  This also means that you have the power to do what no one else in the community can do, which is to end arguments by just stating the way it should be.  We will all understand if this is not a responsibility you want to take on, but the community will grow better if you do.

So, please, if you are willing, step in and state your opinion to help those that build on your work stay on the right track.

[freqmax]

http://rapidshare.com/files/46443453/minimig.sch.html
Almost complete.

[jkonstan]

I agree with Dennis to keep the 1st batch/run of MiniMIGs compatible so that the base set of Verilog HDL and 68K boot code runs on it so enhancements to these can be added on a stable hardware platform. Some kind of very limited expansion could be via the four pins of SPARE I/O FPGA expansion on MiniMIG.

For MiniMIG Gen2 (A1200 like), a 68020 (or maybe even a Freescale 683xx CPU32) would be probably be the way to proceed. With the dynamic bus sizing on the 68020, we could choose a 32bit or 16bit databus back to the FPGA where some similarity to 68000 Bus exists in 16bit 68020 bus mode. A 68020, SDRAM, IDE, compact FLASH, Amiga Clock port, and maybe USB would be good for Gen2. The issue that we are going to have is runnig out of pins on a QFP Xilinx FPGA. Gen 2 MiniMIG could really use a bigger Xilinx FPGA in a BGA package; however, this would push us into a 4 or 6 layer PCB and also require BGA rework equipment to assemble. SDRAM controller is available in Xilinx MIG/Core generator and also on www.OpenCores.com. I have in the past written Compact Flash and PIO IDE controllers in Verilog as well as designed 68020 embedded hardware. I am willing to help on a MiniMIG Gen2.

 :-)

[amigadave]

I hope that most here will agree with the common sense that Dennis and others are suggesting for the first run of v1.1 Minimigs.  Then v2.0 can be discussed and designed over the next two weeks :-P (couldn't resist the Amiga joke of the decade) and another production run with the new design and compatible verilog code to make it work can be tested by a few brave souls.  

I am good friends with the owner of a plastic injection molding business that I can talk to about doing a limited run of cases for a Minimig joystick, if the PCB can be designed to a reasonable size for such an implementation.  Dennis' original size would work for such and only be a little over sized compared to most other Amiga joysticks.  I like the 12cm by 12cm form factor with the ports as Dennis had on the v1.0 design.  I could easily design a replacement bottom half for a joystick I already have in mind to accept the Minimig and complete the casing with the joystick on top.

[basman74]

Belial6 wrote:
@amigadave


Who would be interested in spending $150 now on a MiniMig 1k, knowing that there will be a better model available a year from now?

I definitly am.  I have no problem spending a $150 today, so that production gets started.

If someone is willing to do a 'pilot run' of 100 units (and 100 people commited to purchase :-P ), then I believe this is what it will take to get the process started. This would allow for further 'tweaking' of the design (if necessary) or hacking on 'improvements' etc.

Also, I for one would be happy to put my hand up to organise such a pilot run . Unfortunately, I am committed to my current (work) projects for another week or so, so I would not be able to do anything until then.

Probably at some point before then, we might receive an update from the original poster of this thread. ;-)

Cheers,

Valentin