2fbab8067a
We now track the last time the background task ran and bail on the PulseIn if it starves the background work. In practice, this happens after the numbers from pulsein are no longer accurate. This also adjusts interrupt priorities so most are the lowest level except for the tick and USB interrupts. Fixes #516 and #876
110 lines
4.1 KiB
C
110 lines
4.1 KiB
C
/*
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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) 2017 Scott Shawcroft for Adafruit Industries
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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 "tick.h"
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#include "peripheral_clk_config.h"
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#include "supervisor/shared/autoreload.h"
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#include "shared-module/gamepad/__init__.h"
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#include "shared-bindings/microcontroller/__init__.h"
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#include "shared-bindings/microcontroller/Processor.h"
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// Global millisecond tick count
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volatile uint64_t ticks_ms = 0;
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void SysTick_Handler(void) {
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// SysTick interrupt handler called when the SysTick timer reaches zero
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// (every millisecond).
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common_hal_mcu_disable_interrupts();
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ticks_ms += 1;
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// Read the control register to reset the COUNTFLAG.
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(void) SysTick->CTRL;
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common_hal_mcu_enable_interrupts();
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#ifdef CIRCUITPY_AUTORELOAD_DELAY_MS
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autoreload_tick();
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#endif
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#ifdef CIRCUITPY_GAMEPAD_TICKS
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if (!(ticks_ms & CIRCUITPY_GAMEPAD_TICKS)) {
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gamepad_tick();
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}
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#endif
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}
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void tick_init() {
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uint32_t ticks_per_ms = common_hal_mcu_processor_get_frequency() / 1000;
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SysTick_Config(ticks_per_ms-1);
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NVIC_EnableIRQ(SysTick_IRQn);
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// Set all peripheral interrupt priorities to the lowest priority by default.
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for (uint16_t i = 0; i < PERIPH_COUNT_IRQn; i++) {
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NVIC_SetPriority(i, (1UL << __NVIC_PRIO_BITS) - 1UL);
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}
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// Bump up the systick interrupt.
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NVIC_SetPriority(SysTick_IRQn, 1);
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NVIC_SetPriority(USB_IRQn, 1);
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}
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void tick_delay(uint32_t us) {
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uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
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uint32_t us_until_next_tick = SysTick->VAL / ticks_per_us;
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uint32_t start_tick;
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while (us >= us_until_next_tick) {
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start_tick = SysTick->VAL; // wait for SysTick->VAL to RESET
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while (SysTick->VAL < start_tick) {}
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us -= us_until_next_tick;
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us_until_next_tick = 1000;
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}
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while (SysTick->VAL > ((us_until_next_tick - us) * ticks_per_us)) {}
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}
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// us counts down!
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void current_tick(uint64_t* ms, uint32_t* us_until_ms) {
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uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
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// We disable interrupts to prevent ticks_ms from changing while we grab it.
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common_hal_mcu_disable_interrupts();
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uint32_t tick_status = SysTick->CTRL;
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uint32_t current_us = SysTick->VAL;
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uint32_t tick_status2 = SysTick->CTRL;
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uint64_t current_ms = ticks_ms;
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// The second clause ensures our value actually rolled over. Its possible it hit zero between
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// the VAL read and CTRL read.
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if ((tick_status & SysTick_CTRL_COUNTFLAG_Msk) != 0 ||
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((tick_status2 & SysTick_CTRL_COUNTFLAG_Msk) != 0 && current_us > ticks_per_us)) {
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current_ms++;
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}
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common_hal_mcu_enable_interrupts();
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*ms = current_ms;
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*us_until_ms = current_us / ticks_per_us;
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}
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void wait_until(uint64_t ms, uint32_t us_until_ms) {
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uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
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while (ticks_ms <= ms && SysTick->VAL / ticks_per_us >= us_until_ms) {}
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}
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