I am using a K60 twr board, and i have a delay function like this.
unsigned int i, n;
When i checked the number of cpu cycles (using the systick) it takes,it showed around 3000, which is theoretically correct (optimized code for speed, so 1000nop + 1000 add + 1000 cmp)
Since my cpu is 120Mhz, if i set and reset a gpio before and after calling this delay, i expect
theoritically -> 3000 cpu cycles X 0.0083micro seconds = 25 micro seconds
but, practically (by setting and resetting gpio) i am seeing it as around 143 micro seconds.
Any idea why this difference? I am really running my core @ 125?, or is my calcultion wrong somewhere?
My systick configurtaio
SYST_RVR = 0xFFFFFFFF;
SYST_CSR = 0x7;
int nStart = SYST_CVR;
int nStop = SYST_CVR;
thanks in advance