NeoPixel clear() method wont clear pixels

[mic159]

It only clears the local state, not the buffer on the seesaw.

The code only memsets the local buffer: https://github.com/adafruit/Adafruit_Seesaw/blob/ddd69568db4389ad735df1088d27507a48548d3e/seesaw_neopixel.cpp#L287

And there does not appear to be any command on the seesaw to actually clear it either: https://github.com/adafruit/seesaw/blob/ad471bd26fd5ddb4b320dafd0275e58e5f052714/include/event.h#L118

What is the best way to clear all pixels? Looping all pixels and calling setPixelColor seems inefficient. Can we use NEOPIXEL_SET_BUFFER_REQ to set all pixels to 0 at once?

[ladyada]

call show() https://github.com/adafruit/Adafruit_Seesaw/blob/ddd69568db4389ad735df1088d27507a48548d3e/seesaw_neopixel.cpp#L102

[mic159]

@ladyada the show() function only sends the SEESAW_NEOPIXEL_SHOW command to the NeoTrellis/Seesaw, but the buffer on the NeoTrellis/Seesaw still has the original pixel data, so the LEDs stay lit up as they were.

https://github.com/adafruit/Adafruit_Seesaw/blob/ddd69568db4389ad735df1088d27507a48548d3e/seesaw_neopixel.cpp#L114

Simple reproduce case:

#include "Adafruit_NeoTrellis.h"

Adafruit_NeoTrellis pad;

void setup() {
  pad.begin();
}

void loop() {
  pad.pixels.setPixelColor(0, 255, 0, 0);
  pad.pixels.setPixelColor(15, 255, 0, 0);
  pad.pixels.show();
  delay(1000);
  pad.pixels.clear();
  pad.pixels.show();
  delay(1000);
}

This should blink the pixels, but it just stays solid.

[ladyada]

ooooooooooooooh - yeah thats a bug. sorry no fix at this time because the firmware is pre-burned :( you have to write to each pixel!

[ladyada]

wanna try adding a this->write(SEESAW_NEOPIXEL_BASE, SEESAW_NEOPIXEL_BUF, writeBuf, len + 2 ); type call after the memset in clear()? that should then send that data buffer off, may need adjustment for variable names n such - i dont have a seesaw on hand right now to test

like... https://learn.adafruit.com/adafruit-seesaw-atsamd09-breakout/neopixel#buf-0x04-32-bytes-write-only-12-3

[mic159]

@ladyada yes, it looks like we can use SEESAW_NEOPIXEL_BUF a few times to clear the buffer on the remote end. Unfortunately the buffer is larger than the 32 byte maximum of TwoWire, so it has to be called in a loop.

Check #21