I2C LCD 2004 16x2 with PCF8574

Hello, I’ve been struggling for weeks trying to make the classic LCD 16x2 I2C PCF8574 work with the BBB. Tried python code and C/C++ code from different sources, none of them worked, all I get is the screen’s light blinking whenever a command is sent. I am currently using the LiquidCrystal_I2C_h library form Adafruit.

I can see the device with the address 0x27 when I i2c detect.

Can anyone help please.

Are you able to use the PCF8574 as a simple I/O expander first? Like take a step back from the LCD part and talk to it as a port. Set each bit on or off with a simple program.

PCF8574out 01
would set bit 0. Then check that with a meter or if you have a scope see if you can capture the bit stream.