as the subject line suggests:
When attempting output digital data at high speeds I have noticed an anomaly, the pulse width randomly increases or decreases by 5us.
This occurs regardless of the code used to modify the pin levels. (digitalWrite, directly modifying the entire PORT register, using bitWrite or bitSet on the port register). Thus i am forced to conclude the delay is occurring at a hardware level between the port register and the transistors controlling the IO pins.
Upon examining the signals sent by the Serial library over Tx there appears to be a 10us shift that appears. this is extremely puzzling since the computer is still able to receive the data even at 115200 baud (pulse width 8.7us).
All of this data has been recorded independently of the 3us delay between the void loop() ending and restarting.
Any hints on enabling High speed communication over the digital pins would be appreciated. this 5us delay in level shifting interferes even at 9600baud.