How many clock cycles are in nop instruction?

Answer 1

nop assembly instruction cycle time does differ by the microcontroller type but mostly they don't differ much anyway, I think if i remember well on AVR nop uses 1 cycle, on ARM Cortex M3 nop uses either 2 or 3 cycles depending on several other conditions, PIC uses also 1 clock cycle for its nop instruction but generally all PIC instruction use 4 or even more clock cycle as result of PIC MCU which are non-pipelined and take 4 clock cycles per instruction cycles! for this reason PIC MCU's Oscillator Frequency is always divided by 4 to compensate with the pipelining. this also means that a typical AVR is 4 times faster than PIC. Thus a PIC MCU needs 80 MHz clock to match a typical 20 MHz AVR in terms of speed. ofcourse assuming that both MCU are running exactly the same assembly instructions otherwise if remember well on average PIC's instruction take less cycles than AVR's therefore if both MCU aren't running exact identical assembly program Yes on average AVR will always be faster but probably not exactly twice as much because of some of its instruction taking more cycles than PIC's.

I hope the above helps.

Nshuti Olivier

Massey University - Albany

NZ.