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/*
* This file is part of the Micro Python project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2013, 2014 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include STM32_HAL_H
#include "py/obj.h"
#include "irq.h"
#include "systick.h"
// We provide our own version of HAL_Delay that calls __WFI while waiting, in
// order to reduce power consumption.
void HAL_Delay(uint32_t Delay) {
if (query_irq() == IRQ_STATE_ENABLED) {
// IRQs enabled, so can use systick counter to do the delay
extern __IO uint32_t uwTick;
uint32_t start = uwTick;
// Wraparound of tick is taken care of by 2's complement arithmetic.
while (uwTick - start < Delay) {
// Enter sleep mode, waiting for (at least) the SysTick interrupt.
__WFI();
}
} else {
// IRQs disabled, so need to use a busy loop for the delay.
// To prevent possible overflow of the counter we use a double loop.
const uint32_t count_1ms = HAL_RCC_GetSysClockFreq() / 4000;
for (int i = 0; i < Delay; i++) {
for (uint32_t count = 0; ++count <= count_1ms;) {
}
}
}
}
// delay for given number of microseconds
void sys_tick_udelay(uint32_t usec) {
if (query_irq() == IRQ_STATE_ENABLED) {
// IRQs enabled, so can use systick counter to do the delay
uint32_t start = sys_tick_get_microseconds();
while (sys_tick_get_microseconds() - start < usec) {
}
} else {
// IRQs disabled, so need to use a busy loop for the delay
// sys freq is always a multiple of 2MHz, so division here won't lose precision
const uint32_t ucount = HAL_RCC_GetSysClockFreq() / 2000000 * usec / 2;
for (uint32_t count = 0; ++count <= ucount;) {
}
}
}
bool sys_tick_has_passed(uint32_t start_tick, uint32_t delay_ms) {
return HAL_GetTick() - start_tick >= delay_ms;
}
// waits until at least delay_ms milliseconds have passed from the sampling of
// startTick. Handles overflow properly. Assumes stc was taken from
// HAL_GetTick() some time before calling this function.
void sys_tick_wait_at_least(uint32_t start_tick, uint32_t delay_ms) {
while (!sys_tick_has_passed(start_tick, delay_ms)) {
__WFI(); // enter sleep mode, waiting for interrupt
}
}
// The SysTick timer counts down at 168 MHz, so we can use that knowledge
// to grab a microsecond counter.
//
// We assume that HAL_GetTickis returns milliseconds.
uint32_t sys_tick_get_microseconds(void) {
mp_uint_t irq_state = disable_irq();
uint32_t counter = SysTick->VAL;
uint32_t milliseconds = HAL_GetTick();
uint32_t status = SysTick->CTRL;
enable_irq(irq_state);
// It's still possible for the countflag bit to get set if the counter was
// reloaded between reading VAL and reading CTRL. With interrupts disabled
// it definitely takes less than 50 HCLK cycles between reading VAL and
// reading CTRL, so the test (counter > 50) is to cover the case where VAL
// is +ve and very close to zero, and the COUNTFLAG bit is also set.
if ((status & SysTick_CTRL_COUNTFLAG_Msk) && counter > 50) {
// This means that the HW reloaded VAL between the time we read VAL and the
// time we read CTRL, which implies that there is an interrupt pending
// to increment the tick counter.
milliseconds++;
}
uint32_t load = SysTick->LOAD;
counter = load - counter; // Convert from decrementing to incrementing
// ((load + 1) / 1000) is the number of counts per microsecond.
//
// counter / ((load + 1) / 1000) scales from the systick clock to microseconds
// and is the same thing as (counter * 1000) / (load + 1)
return milliseconds * 1000 + (counter * 1000) / (load + 1);
}
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