diff options
| -rw-r--r-- | ports/stm32f4/common-hal/microcontroller/__init__.c | 36 |
1 files changed, 30 insertions, 6 deletions
diff --git a/ports/stm32f4/common-hal/microcontroller/__init__.c b/ports/stm32f4/common-hal/microcontroller/__init__.c index af7718724..1ac8f474c 100644 --- a/ports/stm32f4/common-hal/microcontroller/__init__.c +++ b/ports/stm32f4/common-hal/microcontroller/__init__.c @@ -39,15 +39,39 @@ #include "supervisor/filesystem.h" #include "supervisor/shared/safe_mode.h" -// This routine should work even when interrupts are disabled. Used by OneWire -// for precise timing. +#include "stm32f4xx_hal.h" + +//tested divisor value for busy loop in us delay +#define LOOP_TICKS 12 + +STATIC uint32_t get_us(void) { + uint32_t ticks_per_us = HAL_RCC_GetSysClockFreq()/1000000; + uint32_t micros, sys_cycles; + do { + micros = ticks_ms; + sys_cycles = SysTick->VAL; //counts backwards + } while (micros != ticks_ms); //try again if ticks_ms rolled over + return (micros * 1000) + (ticks_per_us * 1000 - sys_cycles) / ticks_per_us; +} + void common_hal_mcu_delay_us(uint32_t delay) { - // sys freq is always a multiple of 2MHz, so division here won't lose precision - const uint32_t ucount = HAL_RCC_GetSysClockFreq() / 2000000 * delay / 2; - for (uint32_t count = 0; ++count <= ucount;) { + if (__get_PRIMASK() == 0x00000000) { + //by default use ticks_ms + uint32_t start = get_us(); + while (get_us()-start < delay) { + __asm__ __volatile__("nop"); + } + } else { + //when SysTick is disabled, approximate with busy loop + const uint32_t ucount = HAL_RCC_GetSysClockFreq() / 1000000 * delay / LOOP_TICKS; + (void)start; + for (uint32_t count = 0; ++count <= ucount;) { + } + } } volatile uint32_t nesting_count = 0; + void common_hal_mcu_disable_interrupts(void) { __disable_irq(); __DMB(); @@ -58,7 +82,7 @@ void common_hal_mcu_enable_interrupts(void) { if (nesting_count == 0) { // This is very very bad because it means there was mismatched disable/enables so we // "HardFault". - HardFault_Handler(); + asm("bkpt"); } nesting_count--; if (nesting_count > 0) { |