Hello all, I'm having a weird issue. I am using an I/O pin on the AVR to turn on/off the backlight of an LCD. I am not, however, switching the backlight directly from the AVR. Instead, I am using a PNP transistor. See attached circuit. The problem I am having is when the I/O pin is programmed low, there is still voltage (~4V) seen at the I/O pin, and when the pin is programmed high there is 5V seen on the pin (as expected). Essentially, the backlight is always on. I disconnected the transistor and 10k pull-down resistor from the avr, and, as expected, when the pin is programmed low there is 0v seen and when programmed high there is 5v seen. So the AVR is working properly. Any ideas why I'm seeing a voltage on the I/O pin when its programmed low? Any help would be great.
Joined: Fri. Aug 15, 2008
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