Quote Originally Posted by richard View Post
interpreted as [( 7bit_addr, EN, RW, RS, D4, D5, D6, D7, Backlight, POLARITY) ]

the PCF8574 datasheet indicates the 7bit addr range is 0x20--0x27

0x3f is not valid afaik.

default with a0:2 open = 7bit_addr of 0x27 , pbp addr would be $4e
I see on the data sheet for the PCF8574 you are right I used the Arduino i2c address finder to get the address. I have tried it using the 4E address and get nothing however with the 7E I do get some response from the display. I am still trying to understand the Initialization string and how to use it if you can offer guidance it would be appreciated. This is a little beyond my current ability but I will continue to try to learn and get this project going.

Thank You!