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[beken-72xx] Implement accurate delayMicroseconds() (#26)

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* Implements accurate delayMicroseconds

* renamed to cammelCase, moved #defines and clang-formatted
This commit is contained in:
David Buezas
2022-10-03 15:14:31 +02:00
committed by GitHub
parent 18653781d5
commit 303def49cb
1 changed files with 37 additions and 10 deletions
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47
arduino/beken-72xx/cores/arduino/wiring.c
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@@ -7,17 +7,50 @@
#include <rtos_pub.h>
#include <sys_rtos.h>
#define TICKS_PER_US (CFG_XTAL_FREQUENCE / 1000 / 1000)
#define TIMER0_US_OVERFLOW (portTICK_PERIOD_MS * 1000)
#define TICKS_PER_OVERFLOW (TICKS_PER_US * TIMER0_US_OVERFLOW)
void delayMilliseconds(unsigned long ms) {
rtos_delay_milliseconds(ms);
}
static uint32_t getTicksCount() {
uint32_t timeout = 0;
REG_WRITE(TIMER0_2_READ_CTL, (BKTIMER0 << 2) | 1);
while (REG_READ(TIMER0_2_READ_CTL) & 1) {
timeout++;
if (timeout > (120 * 1000))
return 0;
}
return REG_READ(TIMER0_2_READ_VALUE);
}
void delayMicroseconds(unsigned int us) {
// TODO implement this properly
us /= 10;
#if LT_MICROS_HIGH_RES
if (us == 0)
return;
us--;
uint32_t startTick = getTicksCount();
/* startTick2 accounts for the case where the timer counter overflows */
uint32_t startTick2 = startTick - TICKS_PER_OVERFLOW;
uint32_t delayTicks = TICKS_PER_US * us;
while (delayTicks > TICKS_PER_OVERFLOW) {
// The delay is longer than what the timer can count.
// Let it overflow until only a fraction of TICKS_PER_OVERFLOW remain.
while (getTicksCount() > startTick) {}
while (getTicksCount() < startTick) {}
delayTicks -= TICKS_PER_OVERFLOW;
}
while ((getTicksCount() - startTick < delayTicks) || // normal case
(getTicksCount() - startTick2 < delayTicks) // counter overflow case
) {}
#else
volatile uint32_t i, j;
for (i = 0; i < us; i++) {
for (j = 0; j < 100; j++) {}
for (j = 0; j < 6; j++) {}
}
#endif
}
unsigned long millis() {
@@ -33,13 +66,7 @@ unsigned long micros() {
#endif
#if LT_MICROS_HIGH_RES
REG_WRITE(TIMER0_2_READ_CTL, (BKTIMER0 << 2) | 1);
while (REG_READ(TIMER0_2_READ_CTL) & 1) {
timeout++;
if (timeout > (120 * 1000))
return 0;
}
return millis() * 1000 + REG_READ(TIMER0_2_READ_VALUE) / (CFG_XTAL_FREQUENCE / 1000 / 1000);
return millis() * 1000 + getTicksCount() / (CFG_XTAL_FREQUENCE / 1000 / 1000);
#else
#if 0
REG_WRITE(TIMER3_5_READ_CTL, (BKTIMER3 << 2) | 1);