timer - AVR/Arduino: reading timer toggled port pin

Question

I've configured the timer 2 in CTC mode and to toggle the port pin on compare match (TCCR2A=0x42, TCCR2B=0x02, OCR2A=0x20) and have set DDR3 to output. Hence, according to the ATmega328P documentation (pages 158-163). OC2A (aka PB3) should toggle on each compare match. Unfortunately, I can't read the pin state at PORTB. Is this expected? I assumed, that even if a port is configured as output I can read the set value.

Answer 1

There were two problems:

1. In AVR Studio 4.18 I must not use the Simulator 1, because it has a bug for the timer 2 and hence can't toggle the port pin correctly. I needed to use Simulator 2 or AVR Studio 5.

2. I needed to read PINB instead of PORTB (though the toggling is an output operation).

Answer 2

I don't know about that specific microcontroller, but in some architectures you need at least a NOP between changing the port pin and the latch being updated (so you can read the change).

Also there is the maximum frequency a pin can be toggled at (many times slower than the microcontroller CPU clock). Be sure to not be over that frequency.