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