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New year, new direction - Part II

A project log for 'Flea Ohm' FPGA Project

My attempt at making an FPGA experimenters board in a popular form factor :)

valentin-angelovskiValentin Angelovski 02/23/2017 at 10:552 Comments

Hello again!

Sorry about the delay in my last reply. Non-hobby matters, along with the added frustration over long part lead-times etc. did slow things down here quite a bit..

Rather than wait an unknown lead-time on an FPGA part that I need, thought I'd try for a redesign of my Ohm board using larger (but more readily available) parts. While this might result in a larger (and more expensive) board, thought I'd also take this opportunity to make it a bit more useful..

So, whilst I was in the process of exploring FPGA alternatives, (where nothing is really jumping out at me right now - apart from maybe Max-10) I gave Lattice and another variant of their ECP5 series one more spin..

Anyway, here's my result (did I mention it's a bit bigger than before? :-) :

I've retained all the existing Ohm board functions, but added a flexible lvds header (for display or camera modules, potentially) and also 10/100 Ethernet.

Regarding the external DRAM: I have completed several versions of the above-mentioned design with different external RAM chips loaded, from SDRAM through to DDR3..

I realize this is a major deviation from the original (pi zero form factor) design. However cool that was (and still is, I've not forgotten), I've decided that I always wanted to do something in-between a zero and a full-blown pi. Through this renewed effort, it will be as close as I'm ever going to get. :-)

Next step: To decide upon the external RAM, review and then try fabricating one (or more) of these guys..

Thanks for reading! :-)

Cheers,

Valentin

Discussions

elpekos wrote 02/28/2017 at 14:55 point

Hi Valentin,

I hope that you will be able to design this board  compatible with the Pi board size and layout. It should be compatible with the existing accessories like boxes, LCD screens...

Cheers,

Thierry

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Valentin Angelovski wrote 03/01/2017 at 14:42 point

Hi Thierry,

While you make a valid point, my problem here is this - 12 months ago I actually attempted the layout for a full-sized raspi form factor.. I was unhappy with my solution at that time (i.e. getting too complex and costly to make). Not much has changed since then in my opinion..

With the Ohm PCB re-design, I lean more towards the Orange Pi one, but I did not like the fact it had only one USB port so I added a second one.. :-)

Conclusion: Boxes can always be 3D printed (and the current flea Ohm has external interconnects on only two sides of the PCB which makes sticking it into a standard generic box arguably easier than the regular pi), and LCD panels need not be limited to (as far as I can tell) 800x480.. ;-)

Cheers, Valentin

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