RaspberryPI

Raspberry PI with HD44780 LCD and I2C Interface Board

Sven Bachmann
After buying an HD44780 compatible LCD together with an I2C interface board (which has an PCF8574T soldered on it) I tried to output some text in C on it but the display just stayed black - or after changing some GPIOs, it stayed blue. I measured every pin of the PCF8574T and got the following scheme: PCF8574T <-> HD44780 P0 -- RS P1 -- R/W P2 -- EN P4 -- DB4 P5 -- DB5 P6 -- DB6 P7 -- DB7 R/W should be mapped to GND if the HD44780 should not talk back to the CPU.