I bought an ATMega328P-PU and burned OptiBoot onto it using a second Arduino Uno R3 with great success.
I then put the microcontroller back on the (empty) Uno R3 (DIP) Board for programming, connected USB and uploaded the blink sketch successfully.
Now to the weird stuff:
Blink works on the Arduino Board itself, but if I pull it out and stick it into my breadboard, the program seems to not start. Here are some facts:
- happens with or without external crystal
- happens with or without the 22pF capacitors from
- happens with Fuses set to internal OSC or to external clock (Uno default)
- happens with or without the
ADC VCC(Pin 20) and
REFERENCE(Pin 21) Pins @ 5V
- happens on 5V and on 3V3
- happens with or without external Pullup on
- Most of the output Pins sit at