Uint8Array over SPI

_bufferSize is the length of the graphics buffer, in my case 5808 bytes (176*264/8).

So the code is this (inside a lot more code):

IL91874.prototype.grfxBlackWhite = function () {  
  var _display = this;
  var g = Graphics.createArrayBuffer(
            this.display.displaySizeX,
            this.display.displaySizeY,
            this.display.bpp,
            {msb: true}
          );
  g.clear = function(clearColor){    
    new Uint8Array(this.buffer).fill(clearColor);print(this);
  };
  g.flip = function(callback){     
	//this does not work
	_display.wCmd(_display.display.CMD.DATA_START_TRANSMISSION_1);
	_display.wData(this.buffer); 
    
	//this works
    //_display.wCmd(_display.display.CMD.DATA_START_TRANSMISSION_1);
    //for (let i=0;i<this.buffer.length;i++) _display.wData(this.buffer[i]);
     
    _display.waitBusy(callback);
  };
  return g;
};
IL91874.prototype.wCmd = function (command) {
  digitalWrite(this.dcPin, 0);
  this.spi.write(command, this.cs1Pin);  
};
IL91874.prototype.wData = function (data) {
 digitalWrite(this.dcPin, 1);
 this.spi.write(data, this.cs1Pin);
};

So what it does is, when flip is called, transmit the buffer data to the papers ram.

It is actually only a modification of the SSD1606 module code. In there the flip function it does exactly the same: transmit the buffer data via SPI as an Uint8Array (as I just learned, more a view to the buffer?).
Maybe that's the problem? I'm assuming that what works in the example code also would work in my case.

Otherwise I can only think of a problem in transmitting speed. I played around with the SPI baud rate (set it lower) but to no avail.

I mean, the code does work, but writing 2 buffers (one for red, one for black) takes about 3.5s each + the 15s update cycle of the paper. I think there is potential for speeding up things.