Valentin AngelovskiHello Again!
Before I continue on with RAM testing on the Ohm+, thought I'd do some more testing of the Ohm board's ADC and PWM capabilities.
For this test, I knocked up a 'quick and dirty' Video overlay, with the FleaFPGA Ohm providing a 256x64 bitmap overlay for a video signal from a reverse parking camera. Here is a picture of the test setup:
As you can see, there isn't really much to it! :-)
In the above pic, RCA plug into the mini 'hat' is feeding into one of Flea Ohm's ADC inputs from the reversing camera (shown left). While the other RCA connection (bottom right) is connected to a PWM output pin with overlaid video driving a TV monitor (shown in the next picture.. :-).
Anyway, here's our test result... and the result was better than expected:
Admittedly, there is some noticeable loss in image quality as I am running the ADC and PWM @ approximately 6-7 bits resolution. However, I did not believe it would work as well as it did. While I am running the ADC and PWM sample clocks at 20% above normal (effectively over-clocking the ADC), I suspect there may be room for improved performance via tweaks to the hdl - tweaks that may allow the ADC to meet the FPGA's timing requirements at the faster sample clock. Still, it is good to see what Flea Ohm's humble ADC and PWM pins could be capable of..
Well, that's it for now - back to more testing! :-)
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Yay Amiga! Thats what i'm into right now too. My classic amigas (A500s and A600s) are starving for some (Flea?)fpga love. I'm thinking about HDMI and CPU (TG68k) upgrades for them right now.
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Wow, that is a pretty impressive ADC demo! Even at 6-7 bits-per-pixel, that seems quite useful. What is the ADC capture speed you are using (and PWM modulation speed)?
Now all you need is to add a mode to make MiniMig emulate an old-school Amiga-Live! NTSC capture board using this. :-)
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Hello Xark!
ADC and PWM blocks in this demo are being driven by a 312.5MHz clock, which is 25% above the normal rate (and overclocking the ADC significantly, though I believe with more careful design it could be made to meet timing constraints - this was a quick and dirty demo after all).
Further work would be needed to see how well it could convert the sampled composite NTSC into RGB with useful accuracy. Still, it's not too bad given I had originally intended it mainly for audio and/or ultrasonic apps..
While my current focus is to port more modern system examples to Flea Ohm, an FPGA Amiga with video capture capability would be really cool! :-)
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