Arduino Uno (ATMega328P Microcontroller) running inline assembly instructions using asm statements. Global interrupts disabled. Pin 13 (PORTB5), DDRB5 designated as output used for trigger event for oscilloscope. The oscilloscope is measuring voltage drop of resistor soldered to VCC on microcontroller and using pin 13 toggle as trigger event. Clock of microcontroller is 16MHZ and the oscilloscope is sampling at 1.25GHZ.
The traces acquired from the setup above are relatively uniform. However, they give some odd behaviour causing some errors in my analysis. Every 8 or 16 clock cycles, the waveform will peak on the trailing edge. Reading documentation of the microcontroller about the fetch-load-execute cycle does not lead to any nice conclusions. Has anyone else encountered this issue?