setPanelBrightness() corrupts top line when using colour depth of less than 4 bits

[mickjc750]

Hi,

I recently started experimenting with this library to see if it would suit my application. I started with your demo test sketch, and configured it for 4 panels of 64x32. At this point I only have 1 of the 4 panels connected, so can only see x of 192-255.

I don't need much colour depth, so I configured it for only 2 bits using setPixelColorDepthBits(2), then started experimenting with how intensity is handled, by displaying a gradient and dimming the display with setPanelBrightness().

The lowest visible intensity with 2bit depth is corrupted in the top row if I use either 2 or 3 bits of colour depth (see picture).

I produced the attached image by putting the following into loop() on your test sketch (and speeding up the cycles to 200mS).

static uint8_t b = 255; Serial.printf("panel brightness: %u\n", b); x = 192; while(x != 256) { c = (x-192)*4; matrix->drawFastVLine(x,0,25, c, c, c); x++; }; matrix->setPanelBrightness(b); b--;

It's not a show stopper for me, as there is enough ram with this configuration to run 4 bits of colour depth, but It's a shame to waste the ram if the colour depth isn't needed.

[mickjc750]

mxconfig.clkphase = false; fixed it... (sorry).

Thanks for a great library, looks like it will do everything I need :-)