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Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
@allObjects
On Espruino-WiFi w/ 2v01, I have a 9 by 4 graphics instance of Graphics with 24 bpp. The graphics is updated on external events. The events are detected by watched and polled pin changes and statuses. For the display panel I use a 5V off-initializing neopixel string in line-by-line zig-zag routing that presents like a dot matrix panel. Since I do not want to use the application driven .flip() of moving the display buffer into the display, I have a function on 250[ms] interval that does it. Because the setup, the .flip like logic is very simple:
On a very regular basis I get random green 'erranding' pixel before or after pixels I'm setting in the string direction . Moving my set pixel along the the string by setting current pixel w/ backround color (0) and next or previous pixel with a constant non-backround color (!0), the green 'erranding' pixel keeps leading or following the changing pixel... weird...
Reading the buffer with a JS function, I never see bleeding. All 3 pixel bytes have always left the old place and show all up at the new place.
Event rate is very low compared to neopixel refresh rate (graphics flip rate). Power supply is 3A. Grounds are connected at Espruino board. There are never more 12 pixels on, never all white. Pin mode is set to af_opendrain and data line is pulled to 5V w/ resistor. I varied the resistor between 1K and 330R w/ no different result.
What could cause that? Even with constant refreshing and no change in the graphics buffer, the green 'erranding' pixel stays put. The 'erranders' or really random... also in regard of the row.