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Member since Mar 2023 • Last active Mar 2023
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  • in Puck.js, Pixl.js and MDBT42
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    Wow! I knew some storage must be used up, but I had no idea free space was so limited. I don't think it will affect me as long as I can get the SD card working.
    If I ever do go the trouble of getting compilers running on my current PC (other than Bellard's TinyC :-) ), I might try messing with Puck's firmware. Thank you for all the information.

  • in Puck.js, Pixl.js and MDBT42
    Avatar for user154581

    Oh, sorry; I don't understand well enough. I thought Puck had 512 KB of storage and 64KB of RAM. But you said "reduce it from 40 to 32KB."

    In any case, I won't mess with C or compilers. The only reason I'm using Puck instead of Raspberry Pi zero is to avoid wasted time with compilers.

  • in Puck.js, Pixl.js and MDBT42
    Avatar for user154581

    In my experience, trying to get a compiler to work takes days, while writing a code library takes hours.
    And why would 4 tiny SPI functions need 8KB of RAM??? It will be much less than 1KB in JS. I have maybe 2KB I can sacrifice at most.
    I will work on it when I get home. Thank you again.

  • in Puck.js, Pixl.js and MDBT42
    Avatar for user154581

    Thank you so much! That is very helpful. :-)
    I will code the SD card SPI commands in JS and hopefully still have enough RAM... Somehow.

  • in Puck.js, Pixl.js and MDBT42
    Avatar for user154581

    Any help appreciated! I have a PuckJS.
    I wanted to use E.connectSDCard() after wiring an SD card to pins, but I got

    Uncaught Error: Function "connectSDCard" not found!

    So I printed the keys of E with print( Object.keys( E ) + " < Those were E's Keys" );
    And got:

    [ ] < Those were Es Keys

    I did a hard-reset by holding the button while inserting the battery, then waiting for the LEDs to finish their color changes and the red LED flashed 5 times, then held the button for 1 more second, like the instructions said.
    But E is still an empty object. According to the documentation, it should have many functions available on it. https://www.espruino.com/Reference#E

    I tried looking up the error, but the troubleshooting documentation just tells me to check for a typo. :-(

    Edit: I updated the firmware using the WebIDE a while ago if memory serves, but I have not put any custom firmware on it or anything.

    I have been using the PuckJS to control an E-Ink display over SPI, which is working fine. Only the E object is not working. Is there any other relevant information? Hmm.

    It's a PuckJS V2. The one with almost no pins and an FET.

    I have been trying to make an e-reader by attaching it to a 4.2 inch, 400*300 e-ink display.
    The e-ink display's pixels are 1 bit each (for black-white images). The PuckJS didn't have anywhere near enough power to render a 15KB page from a font using bitwise math ops, nor enough RAM to hold more than 1 page in memory. It would take minutes just to "turn the page".

    I had the idea of streaming a pre-rendered 15KB page over bluetooth, but that turned out to be amazingly difficult. You can't stream binary data over PuckJS's bluetooth, because it uses the ASCII control codes as connection commands. I modified the "puck.js" library to accept array buffers, and used escape characters to work around character codes < 32 (as well as dealing with JavaScript string escapes).

    const hex = code => code.toString(16).padStart(2,0).split(""­).map( c => c.charCodeAt( 0 ) );
    const streamableBinaryArray = [];
    for( const code of binaryArray ) {
        if( code === 0x22 ) streamableBinaryArray.push( 0x5c, 0x22 );
        else if( code === 0x5c ) streamableBinaryArray.push( 0x5c, 0x5c );
        else if( code === 0xa ) streamableBinaryArray.push( 0x5c, 0x6e );
        else if( ( code >= 0x00 && code <= 0x1f ) || code === 0x7f ) streamableBinaryArray.push( 0x5c, 0x78, ...hex( code ) );
        else streamableBinaryArray.push( code );

    I managed to get streaming 1 page down to under 12 seconds, a huge improvement over the several minute mark, but not usable for every page turn.

    Still, it would take about an hour to stream a 300 page book. My idea was to stream the entire book, saving individual pages as files on an SD card. Then, on a page turn forward or back, I could read the appropriate file from the SD card into the array buffer, then stream the array buffer to the e-ink display. (How long will that take? It's still untested...)

    HOWEVER! I cannot. Because E.connectSDCard does not exist. :-|

    I checked Espruino's source over on GitHub, and "jswrap_file.c" defines "connectSDCard", so I don't think it's deprecated. "spi_diskio.c" looks like it's setting up and controlling an SD card, so I think the functionality does actually exist.

    The documentation says "This is not available in devices with low flash memory", but that's a frustratingly useless and ambiguous warning. There's nothing anywhere that I've been able to find specifying what devices have "low flash memory". >:-(
    Does it mean if you use up too high a RAM % the code will become unavailable? Does it mean nothing running Espruino ever has this functionality? (Espruino was specifically designed to run on devices with low memory.) Does it mean certain devices from Espruino's shop do / do not have this functionality? (I don't really care in general, I just want to get an SD card working on my PuckJS. I'm sure I can write the SPI commands myself if that's what I'm supposed to do.)