Minimig PCB run - interest thread

[alexh]

You'll never make an assembled one for £40 not without a huge production run.

I have my hat here... and anyone who knows me will know I am capable of eating it.

[alexh]

It's the upfront cost which is the thing putting me off, to make say 200 boards, populate them, quality test them, ship them.

You are looking at £10,000 up front :-(

That is also assuming that the Minimig sources that have been released are actually functional (Which I will be trying to prove this weekend.)

[alexh]

Xenepp wrote:
£10,000?? Where are you getting your boards done?!

My guy does my boards as small runs, so costs nothing like that. I estimate £20 for a bare unpopulated PCB based on previous runs I've done.

200 * 20 = £4000 and that is before you've paid tooling costs, started buying parts, assembling, testing etc.

To make 200 boards will cost about £10,000 upfront.

Make less than 200 and I think the price per unit will go up beyond most peoples price point.

[alexh]

Too small for all but the most skilled hand solderer. The pitch on the FPGA is very small and there are a lot of pins.

[alexh]

the One chip MSX-machines [snip] Maybe something to think about and make a comparable casing?

At €229 euro's I think it is a TAD expensive ;-)

[alexh]

With an A4000 you can just select NTSC and have a 60Hz output (and with WHDLoad you can force it in games too). That will work with most LCD monitors.

MiniMig cannot (yet) switch to a 60Hz screen mode.

[alexh]

Edit: would it be possible to "upload" new "firmware" to the FPGA? Maybe through the serial port?

Erm, you put the FPGA image on the MMC card. I thought everyone knew that?

For example, an AGA chipset?

You wont be able to update to AGA though. Not with the original MiniMig PCB.

o No 32-bit processor (No real point in AGA without an 020+).

o 16-bit RAM (need 32-bit for AGA).

o 12-bit R2R ladder / Video DAC (need 24-bit for AGA)

You might be able to work around the RAM thing if you ran the RAM interface at 2x speed. (Dunno if that is possible, probably have to run everything at 2x speed and divide down inside FPGA).

I guess you could ignore the lack of colours on the screen. (I've not looked that close at the PCB design, perhaps there are more than 12-bits, OCS/ECS only needs 12-bits but you never know.)

But there is no getting round the CPU bit.

[alexh]

PaSha wrote:
It's composite SYNC I want, for RGB.
'Tie together': as in simply join the two pins together, or should I stick something in between?

You have a chuffin FPGA, just change the verilog!

'OR' the H&V signals internally, wire out the new Csync instead of one or the other, voila ;-)

Even better, wire up the functionality to the 15KHz/31KHz jumper.

31KHz = Separate H & V
15KHz = CSync

Ask nicely and I'll provide you with a modified Amber.v

Oh, BTW: Those wanting to make mods to their MiniMig CORE will need to get hold of this:

http://www.xilinx.com/ise/logic_design_prod/webpack.htm

[alexh]

amigadave wrote:
One question: There should also be a jumper to switch from 50hz to 60hz for the North American and Japanese markets interested in this project.  Please don't make it 50hz only.

AFAIK the design of the MiniMig internals and the V1.0 PCB means that you are stuck with a 50Hz PAL Amiga (for the time being at least).

Because of the way MiniMig's clocking currently works, I dont think you can even change to 60Hz in software like you can a real PAL Amiga. This was discussed on the main MiniMig thread at least once.

You may be able to change the main Crystal from a 4.433619MHz PAL one to a 3.579545MHz NTSC one but you will almost certainly have to play with the DCM to generate the (2x) 7.15909MHz etc.

Although how a 4.433619MHz clock was used to generate a (1.6x) 7.09379 MHz one, I dont quite know.

That alone might not be enough, you *may* need to change some constants (horbeam and verbeam comparisons) in agnus.v for NTSC timing.

I may well be wrong, but you'd have to ask Dennis to be sure.

BTW: Dennis We do appreciate your work of art mate ;-)

[alexh]

If Dennis wanted to make any money from this he would have. He could have made and sold boards... THEN at a later date release the JUST the binary FPGA file.

There was an opportunity for him to make money from this and he chose not to AND provide the source.

He is a great man for doing that. A better man than myself I fear.

I for one would like to contribute to him, if I bought a MiniMig capable PCB.

[alexh]

Count me in. UK based ASIC Engineer with SMT rework station ready ;-)

[alexh]

I dont know about you lot, but I am going to phone up sales of Motorola, Xilinx, Microchip etc. and try and blag some free samples.

[alexh]

freqmax wrote:
makes me wonder how hard it's just to swap the current 68k to something else, pin compatible?

Only thing you could have possibly swapped it for would have been a 68010 but they dont make them anymore, and I doubt they ever made SE variants. 020+ wouldnt be pin compatible. With a few wires and a lot of patience I am sure you could wire on any CPU mounted A500/A600 accelerator.

freqmax wrote:
In short the resistor ladder should use 4220 ohm, 2100 ohm, 1050 ohm, 523 ohm (1% tolerance).

Q. Can you get SMT resistors of such wild values?

[alexh]

Crumb wrote:
It would be nice if someone with fpga and pic coding skills added a "gayle" + hardfile support. It could work with the current design (even if hardfile would be a little slow) but could be useful with OS3.x :-)

As soon as MiniMig hardware arrives this will be one of the first changes. Should be viable.

Simultaneous Floppy Emulation and Hard File access might not be viable though.

We'll see.

[alexh]

freqmax wrote:
alexh:
Why would not simultaneous floppy and harddisc (file) access work?

There is only one interface to the MMC through the PIC and they would have to share.