Cascading Max7219

It doesn't do it right now, but the changes required are trivial. To cope with multiple drivers it seems that you just send the two different bits of data to the same address while keeping CS asserted.

Arduino's library here: https://github.com/lstoll/arduino-libraries/blob/master/Matrix/Matrix.cpp#L129

So it's probably as simple as changing:

raw : function(val) {
      spi.send ([0x9,0],cs); // output raw data
      for (var i=0;i<val.length;i++) {
        spi.send([i+1,val[i]],cs);
      }
      spi.send([0x0C,1],cs); // no shutdown
    },

to:

raw : function(val) {
      digitalWrite(cs,0);
      spi.send ([0x9,0]); // output raw data
      for (var i=0;i<val.length;i++) {
        spi.send([(i&7)+1,val[i]]);
      }
      spi.send([0x0C,1]); // no shutdown
      digitalWrite(cs,1);
    },

One nice extra is that you can actually use Espruino's built-in graphics library with it, so you can do something like...

var g = Graphics.createArrayBuffer(3*8,8,1,{vertical_byte:true});
g.drawString("Hello",0,0);
max.raw(g.buffer);