I'm observing some bizarre behavior with an ATtiny2313 and wanted to know if someone can tell my why.
I pulled a 7-segment LED display out of some junk electronics. This display has 3 digits... Ones, Tens, and just 2 segments for hundred (it can disply the number 1 only).
This display is 16 pin. One of them is common anode, 14 pins are cathodes for the ones and tens digit, and the last pin is a cathode for both segments of the hundreds digit.
So, I'm running at 5v and I've attached the common anode to VTG using a 180 ohm resistor. First things first, I just want to cycle all of the segments until I turn them all on at once (displays the number 8).
Here's the bizarre part. If I use PD0-7, the segment connected to PD0 gets dimmer and dimmer until about 3 segments in it is completely off. I tried this on PORTB and the problem disappears so I don't think it's the display causing the trouble.