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Sun 2020.10.04
I agree with you that; that #5 post specific document does present some confusion over the allowed voltage. It is also very specific that the LCD requires 5V. Without that board schematic, it would be guessing as to whether a boost converter is onboard to create the 5V when using 3V3.
While I'll have to defer to the board designer for a definitive explanation, the Pico schematic implies a small drop over the FET when attempting to pull power, when not supplying at pin 18 BAT_IN. I just measured my Pico using USB power, but with no load, and pin 2 is at 4V6 which is very close to the low end specified to even drive that LCD. Under the assumption that speification sheet is in error, any luck driving from the regulated 3V3 pin 3 as was done in the initial post? (not expecting success however)
As all the Arduino snippets and the Espruino documentation example are suggesting 5V, I'd first check to see if that is what is at pin 2 as is now wired in a loaded condition.
Regarding #7 image and #9 code snippet, SCL and SDA now appear to be wired as needed. Does the same error exist when removing the
lcd.print()line as a possibility to see if I2C comm is occurring during initialization with just the connect function? On a really long shot, I've gotten a few knock off boards (not this module) that have had reversed silk screen. Something to consider, but not likely.
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Robin
@user118421
Thank you very much for helping!
The pin mistake is embarrassing, unfortunately correcting it did not help, still same error. Does the 5v requirement mean I cannot use this display with the Pico? The datasheet seems to me to suggest that either 3.3v or 5v can be used but that’s probably just me not understanding how to read it. I tried connecting the HD44780 to an ESP32 as well as it has a 5v pin but no luck and also tried a Nokia 5110 to the Pico according to instructions but nothing happens. Probably just me doing something wrong but then maybe I could at least stop trying to connect a HD44780 to the Pico?