Displaying bitmaps on an oscilloscope

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b/Hardware publicado por u/Keoni29 November 05, 2015, 10:38:31 PM

Displaying bitmaps on an oscilloscope

I turned my oscilloscope into a raster display using an FPGA. It generates the horizontal and vertical sweep signals to draw the screen in X. Y mode and then modulates the beam to create the image.
A 256x256 dots image is stored in a framebuffer. I can send bitmap files to it from my pc. The data transfer rate is 4Mbit/s. This allows me to animate the image at 60FPS.

I can use this display for other projects. Eventually I hope to make a computer game that uses the display.

Last Edit: November 06, 2015, 08:47:02 AM by Streetwalrus

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u/DarkestEx November 05, 2015, 11:58:25 PM

Sounds awesome

u/novenary November 06, 2015, 08:50:07 AM

This is awesome.

I fixed the youtube embed by the way.

u/Keoni29 November 06, 2015, 02:14:34 PM

I would like to convert animated gifs directly to 1 bits bitmap files that I can then stream to the device. I recall that a community member made a gif viewer for ti calculators. Perhaps I modify this tool to convert images to my own format.

u/novenary November 06, 2015, 04:15:30 PM

I think with imagemagick you should be able to automatically convert images to the format you want then strip the header with a small C program or Python script.

u/Keoni29 November 06, 2015, 07:39:50 PM

If the header is a fixed length I can also strip it using dd.

u/Keoni29 November 06, 2015, 10:37:55 PM

It had to be done. First oscilloscope rickroll.

Last Edit: November 06, 2015, 10:38:47 PM by Streetwalrus

u/novenary November 06, 2015, 10:41:52 PM

Damn, this is awesome. I'm pretty sure this is actually a first too, looks like you're lucky.

u/Dream of Omnimaga November 06, 2015, 10:53:13 PM

I can't watch the video yet, but I saw the pictures and am amazed. Good job Keoni28.

Imagine playing Reuben Quest on an oscilloscope.

u/Keoni29 November 08, 2015, 11:42:51 AM

I can also mirror part of my computer screen to the oscilloscope. I just take a screenshot, convert it and send it to the device. I made a script that does this in a loop so the screen refreshes automatically.

u/novenary November 08, 2015, 12:15:54 PM

That's a pretty cool feature. You should add a VGA input to it and play emulators on the scope.

u/Keoni29 November 08, 2015, 12:28:00 PM

You can only turn the beam on and off. There is no greyscale. The vga picture has to be converted to monochrome and that only looks good with dithering. Doing this on the fly would be very complex. First of all you need a high speed AD converter, then the signal needs to be processed in the fpga. It's much easier to make the PC do all the conversions and then send the result to the fpga.

u/novenary November 08, 2015, 05:59:05 PM

Ah that kind of sucks, I thought you could do some grayscale. :/

u/utz November 08, 2015, 06:01:54 PM

Oh yes, looking good! It'd be even more ace to see some realtime fx on top of the pics/animations though

u/Keoni29 November 08, 2015, 07:17:44 PM

I can sorta do grayscale by making the beam stay at one spot longer to make the dot appear brighter, but it would make the image fuzzy and less stable. With this technique you can display pictures even on scopes without a z-input though. I tested it.