Hi, My UNO's D9 can't correctly drive an LCD backlight. I was expecting to see the backlight fade as I write a value from 0 to 255, just like D6 does! If I use D9 I only see full brightness. Whatever I write it looks like is constantly set on HIGH. BUT, if I drive a simple LED with D9 it works fine and no difference in brightness or something between D9 and D6, looks like exactly the same.
Some example code to explain better:
pinMode(9, OUTPUT); digitalWrite(9, LOW); pinMode(6, OUTPUT); digitalWrite(6, LOW);
If I connect the backlight to D6, backlight is OFF as it should be, but remains ON when I connect to D9. Same problem with analogWrite() 0 to 255. It should work like D6.
Does someone have an idea?
Thank you in advance and sorry for my poor english!
EDIT: I've just tried to set to LOW D3, D5, D6, D9, D10, D11, and to read their value with A0. Every Pin reports "0". With PWM pins set to LOW like this, every pin except D9 can actually turn OFF the brightness. With D9, the brightness just does not react, and remains ON...