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CHG: a better micro second (us) spindely function. At average it has 8-10us delay, but its linear. Making error less when you want to wait longer..

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SpinDelayCountUs(20) gives a delay of 28us.
SpinDelayCountUs(100) gives a delay of 110us.
SpinDelayCountUs(500) gives a delay of 508us.
This commit is contained in:
iceman1001 2016-09-10 21:43:08 +02:00
commit b4a6775b5e
4 changed files with 116 additions and 107 deletions
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13
armsrc/util.c
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@ -236,10 +236,11 @@ int BUTTON_HELD(int ms) {
// attempt at high resolution microsecond timer
// beware: timer counts in 21.3uS increments (1024/48Mhz)
void SpinDelayUs(int us) {
int ticks = (48*us) >> 10;
int ticks = (48 * us) >> 10;
// Borrow a PWM unit for my real-time clock
AT91C_BASE_PWMC->PWMC_ENA = PWM_CHANNEL(0);
// 48 MHz / 1024 gives 46.875 kHz
AT91C_BASE_PWMC_CH0->PWMC_CMR = PWM_CH_MODE_PRESCALER(10);
AT91C_BASE_PWMC_CH0->PWMC_CDTYR = 0;
@ -352,7 +353,6 @@ uint32_t RAMFUNC GetCountUS(){
// By suggestion from PwPiwi, http://www.proxmark.org/forum/viewtopic.php?pid=17548#p17548
//return (AT91C_BASE_TC1->TC_CV * 0x8000) + ((AT91C_BASE_TC0->TC_CV * 2) / 3);
return (AT91C_BASE_TC1->TC_CV * 0x8000) + ((AT91C_BASE_TC0->TC_CV << 1) / 3);
//return (AT91C_BASE_TC1->TC_CV << 16) | ((AT91C_BASE_TC0->TC_CV << 1) / 3);
}
void ResetUSClock(void) {
//enable clock of timer and software trigger
@ -360,7 +360,16 @@ void ResetUSClock(void) {
AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
while (AT91C_BASE_TC1->TC_CV >= 1);
}
// attempt at high resolution microsecond timer
// beware: timer counts in 21.3uS increments (1024/48Mhz)
void SpinDelayCountUs(uint32_t us) {
us += GetCountUS();
us -= 6;
for(;;)
if ( GetCountUS() >= us ) return;
}
// static uint32_t GlobalUsCounter = 0;
// uint32_t RAMFUNC GetDeltaCountUS(){