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  1. PO
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    <p>It seems that you can't print bitmap data directly with printer.write(). The printer expects some special bytes to turn on bitmap printing mode as you can see in the printBitmap() method. (writeBytes(18, 42, chunkHeight, rowBytesClipped))</p> <pre><code>void Adafruit_Thermal::printBitmap( int w, int h, const uint8_t *bitmap, bool fromProgMem) { int rowBytes, rowBytesClipped, rowStart, chunkHeight, x, y, i; rowBytes = (w + 7) / 8; // Round up to next byte boundary rowBytesClipped = (rowBytes &gt;= 48) ? 48 : rowBytes; // 384 pixels max width for(i=rowStart=0; rowStart &lt; h; rowStart += 255) { // Issue up to 255 rows at a time: chunkHeight = h - rowStart; if(chunkHeight &gt; 255) chunkHeight = 255; writeBytes(18, 42, chunkHeight, rowBytesClipped); for(y=0; y &lt; chunkHeight; y++) { for(x=0; x &lt; rowBytesClipped; x++, i++) { PRINTER_PRINT(fromProgMem ? pgm_read_byte(bitmap + i) : *(bitmap+i)); } i += rowBytes - rowBytesClipped; } timeoutSet(chunkHeight * dotPrintTime); } prevByte = '\n'; } </code></pre> <p>Your sketch will need to understand the data coming from the PHP and know when to send individual characters as bytes with printer.write() and when to send bytes as an image with printer.printBitmap(). This way the printer is receiving the proper commands to prep it for printing the appropriate data. You will need to construct some metadata around what you want to print in PHP and send that to the Arduino. A JSON format might look like this:</p> <pre><code>{"reciept": [ { "type": "text", "style": "bold", "value": "Thank you for your purchase" }, { "type": "bitmap", "pos": "center", "value": ".... binary data ..." } ]} </code></pre> <p>Now your Arduino sketch will understand when to send bytes individually as text and when to send a lot of data as a bitmap.</p> <p>A more compact format might use line feeds as a break between segments:</p> <pre><code>F|bold T|Thank you for shopping with us\r P|Center B|...binary data (with \r escaped)... \r </code></pre> <p>Or, you can send the amount of data with each segment to avoid escaping binary data much like the Content-Length header of HTTP</p> <pre><code>F4|boldT32|Thank you for shopping with us\rP6|CenterB3000|...binary data... </code></pre>
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    1. POSending binary commands from PHP to Arduino powered thermal printer
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    1. USchugadie
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    1. COprintBitmap is just calling write behind the scenes. Printing bold etc works correctly, so it must be interpreting the commands sent as bytes correctly (look in the PHP for pack). I think I just have my image data wrong.
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      1. USDachande663
    2. COAre you certain there are no timing issues with sending a byte, then waiting 4 times vs sending 4 bytes then waiting all at once? writeBytes(a, b, c, d) may not be exactly the same as writeBytes(a); writeBytes(b); writeBytes(c); writeBytes(d); I still would not try to re-implement all the C of the thermal library into PHP so that the arduino is just a passthru of bytes - it might work but it might end up with timing issues. I guess a way to debug it is to take some of the Arduino examples and re-write them as pure writeBytes(a) calls. If that works, then it is a problem with the data.
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