I'm embarrassed to say I can't get an I2C LCD to work on my ESP32 module.
I tired 3 different LCDs that work with UNOs, and NANOs (tested)
I tried 2 different ESP32Wroom modules, thinking the first one that I never used may be "bad"
I have tried using the LCD in the eventual program and when that didn't work, I switched to a simple I2C LCD sketch that I've used a zillion times.
I tried a NodeMCu 8266 with same results
I'm on the correct pins, P21 and P22 for SDA and SCL.
I have 5 volts on Vin of the ESP32 and 5 volts on the LCD.
I tried the simple BLINK program in my Arduino IDE and the LED on board blinks, proving I did download something. No errors in compile or download.
On power up or reset, the LCD blinks once then goes black. All 3 LCDs do this. If I pull the power wire off, then ON, the background light turns on bright (no characters), and GOES OFF if I press RESET.
I'm using displays with the I2C piggyback module (PCF8574?).
Do I need terminating resistors for I2C? I use I2C for all kinds of products but don't use resistors for the LCD. I tried turning on pullup resistors in C++ code, but don't know if this applies to the ESP32, as it does ARM CPUS.
What am I doing wrong? It's only 4 wires! Code is only 3-4 lines! Did this 1000 times in my life and it always worked.
Can't get I2C LCD to work on ESP32-wroom
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Re: Can't get I2C LCD to work on ESP32-wroom
Have you tried I2C scanner?
Re: Can't get I2C LCD to work on ESP32-wroom
Yes, lcd at address 27.
Re: Can't get I2C LCD to work on ESP32-wroom
I removed the pullup resistors from one of my displays that pull SDA/SCL lines high to 5 volts.
Without them, the ESP32 is supposed to use teh internal pullups to 3.3 volts.
Doesn't work.
Without them, the ESP32 is supposed to use teh internal pullups to 3.3 volts.
Doesn't work.
Re: Can't get I2C LCD to work on ESP32-wroom
scanner reports x27
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