PCF8574AN port expander with LCD HD44780 problem

Forum 2005-2010 (read only) Hardware Interfacing
1

I have a PCF8574AN on a breadboard with an LCD (HD44780). I've been trying to print something on the screen, but have been unsuccessful. I am using the library from: http://www.xs4all.nl/~hmario/arduino/LiquidCrystal_I2C/ I'm using the Hello World sketch that came with the library. I have it connected as shown in the picture that comes with the library. I have re-checked the connections on the LCD and port expander multiple times. The LCD pinout is identical to the picture that comes with the library.

As a test, I used a blink sketch to write to all of the port expander pins turning them on for one second and then off for one second. This works. I can't get anything to show on the display. Anyone with some experience on this? I welcome your comments.

2

Well, after checking again and removing my protoshield, I plugged my LCD and protoboard directly into my arduino. It works now. Apparently, one of my headers isn't making good contact. I guess this goes to show that you should always check ALL of your connections, regardless of how sure you think you are. Hope this helps someone.