RfidResearchGroup/proxmark3
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added a precision timer ( 0.6ns for 43ms)

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This commit is contained in:
iceman1001 2020-10-09 14:30:34 +02:00
parent 7cdd384242
commit 0c54d13c47
2 changed files with 26 additions and 0 deletions
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25
armsrc/ticks.c
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@ -13,6 +13,31 @@
#include "proxmark3_arm.h"
#include "dbprint.h"
// timer counts in 666ns increments (32/48MHz), rounding applies
// WARNING: timer can't measure more than 43ms (666ns * 0xFFFF)
void SpinDelayUsPrecision(int us) {
int ticks = ((MCK / 1000000) * us + 16) >> 5;
// Borrow a PWM unit for my real-time clock
AT91C_BASE_PWMC->PWMC_ENA = PWM_CHANNEL(0);
// 48 MHz / 32 gives 1.5 Mhz
AT91C_BASE_PWMC_CH0->PWMC_CMR = PWM_CH_MODE_PRESCALER(5); // Channel Mode Register
AT91C_BASE_PWMC_CH0->PWMC_CDTYR = 0; // Channel Duty Cycle Register
AT91C_BASE_PWMC_CH0->PWMC_CPRDR = 0xFFFF; // Channel Period Register
uint16_t start = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
for (;;) {
uint16_t now = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
if (now == (uint16_t)(start + ticks))
return;
WDT_HIT();
}
}
// timer counts in 21.3us increments (1024/48MHz), rounding applies
// WARNING: timer can't measure more than 1.39s (21.3us * 0xffff)
void SpinDelayUs(int us) {

1
armsrc/ticks.h
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@ -20,6 +20,7 @@
void SpinDelay(int ms);
void SpinDelayUs(int us);
void SpinDelayUsPrecision(int us); // precision 0.6us , running for 43ms before
void StartTickCount(void);
uint32_t RAMFUNC GetTickCount(void);