Adafruit 8x8 LED Backpacks

Thanks for the pics - that really clears it up!

It's a bit hacky of them to fiddle the wiring like that!

So yes, looks like you have to do a bitwise operation - but it's not too painful. Something like:

// rotate right
I2C1.writeTo(0x70, 0, 
  (new Uint8Array(g.buffer)).map(function(a) { return (a>>1)||(a<<7); }));
// or you might need to rotate left
I2C1.writeTo(0x70, 0, 
  (new Uint8Array(g.buffer)).map(function(a) { return (a>>7)||(a<<1); }));