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Old 11-28-2018, 06:27 PM   #1
mark03
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Waveform file decoding: how much do we know?

Background: I'm a EE with embedded-systems experience, playing with E-ink. I'd like to use one of the newer EPD panels (E-ink Carta, preferably) in a project, without Linux, using a microcontroller and maybe an FPGA. I'm familiar with some of the previous published work along these lines (mainly http://essentialscrap.com/eink/).

It's clear from the earlier work that you can conjure up your own waveforms for simple black-and-white experiments without too much hassle. Grayscale and partial updates, on the other hand, probably require the vendor's waveforms. I don't see any reason to believe that these waveforms are "magic" either---meaning, I suspect that a reasonably competent engineer "skilled in the art" (to borrow the patent-office phrase) and provided with some basic support, could design good ones from scratch. But to do that, he/she would need a simulation model of the display pixel's behavior in something like MATLAB, for running experiments and performing optimization. And the chance of obtaining *that* is pretty much zero, so hey, maybe we should just figure out how to decode the d**n waveform file...

I realize this is quite a different goal from most of the dev work here. I.e. I don't want to convert from one file to another, or patch a file to work with a different display. I just want to extract waveforms from available data (a .wbf file probably), so that i can use those waveforms in my own driver.

I found the "inkwave" program here: https://github.com/fread-ink/inkwave
This is part of the fread project, which I believe is based here at mobileread? The inkwave source code is quite helpful, but the aim there was to convert wbf into wrf and I just need to understand what the waveform data actually mean. Is this known at all?

Thanks,
Mark
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Old 11-29-2018, 12:48 PM   #2
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I don't recall ever hearing from the fread guy directly here, but I think he does mention MR in some of his material .

AFAICT, his is the only project that went as far as this on the subject (and, err, possibly the only project, period ).
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Old 12-02-2018, 03:20 PM   #3
mark03
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Since posting this I have discovered a .wbf file dump utility:

https://github.com/julbouln/ice40_ei...utils/wbf_dump

This guy implemented a basic EPD controller in an FPGA and was apparently able to extract waveforms from the file. I tried it on one of my wbf files and it prints a bunch of waveforms then segfaults, so obviously a work in progress. I haven't had time to dig much deeper though.

One question I have is what makes the "regal" technology different from the older "direct update" (non-flashing) waveforms? Is regal merely a more-refined version, calibrated at different temperatures, etc.? Or is there some qualitative difference between the two, like storing the history of a pixel and using that to dynamically alter the waveform?
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