mirror of
https://github.com/mytechnotalent/Embedded-Hacking.git
synced 2026-06-11 08:37:50 +02:00
Kevin Thomas
137 lines
3.0 KiB
C
137 lines
3.0 KiB
C
/**
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******************************************************************************
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* @file rp2350_timer.c
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* @author Kevin Thomas
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* @brief TIMER0 alarm driver implementation for RP2350.
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*
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* Configures the TIMER0 tick generator for 1 us resolution
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* from the 12 MHz CLK_REF, then uses alarm 0 with NVIC IRQ
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* to implement a repeating callback at a configurable period.
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*
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******************************************************************************
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* @attention
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*
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* Copyright (c) 2026 Kevin Thomas.
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* All rights reserved.
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*
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* This software is licensed under terms that can be found in the LICENSE file
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* in the root directory of this software component.
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* If no LICENSE file comes with this software, it is provided AS-IS.
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*
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******************************************************************************
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*/
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#include "rp2350_timer.h"
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/**
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* @brief User callback and period stored for ISR re-arm.
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*/
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static timer_callback_t _user_callback;
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/**
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* @brief Alarm period in microseconds for re-arming.
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*/
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static uint32_t _alarm_period_us;
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/**
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* @brief Clear the TIMER0 reset bit in the reset controller.
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* @retval None
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*/
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static void _timer_clear_reset_bit(void)
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{
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uint32_t value;
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value = RESETS->RESET;
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value &= ~(1U << RESETS_RESET_TIMER0_SHIFT);
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RESETS->RESET = value;
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}
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/**
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* @brief Wait until the TIMER0 block is out of reset.
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* @retval None
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*/
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static void _timer_wait_reset_done(void)
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{
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while ((RESETS->RESET_DONE & (1U << RESETS_RESET_TIMER0_SHIFT)) == 0) {
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}
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}
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/**
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* @brief Set the TIMER0 tick generator cycle count to 12.
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* @retval None
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*/
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static void _timer_set_tick_cycles(void)
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{
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TICKS_TIMER0->CYCLES = TICKS_TIMER0_CYCLES_12MHZ;
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}
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/**
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* @brief Enable the TIMER0 tick generator.
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* @retval None
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*/
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static void _timer_enable_tick(void)
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{
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TICKS_TIMER0->CTRL = (1U << TICKS_CTRL_ENABLE_SHIFT);
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}
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/**
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* @brief Enable the alarm 0 interrupt in TIMER0 INTE register.
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* @retval None
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*/
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static void _timer_enable_alarm_irq(void)
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{
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TIMER0->INTE = (1U << TIMER_INTE_ALARM0_SHIFT);
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}
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/**
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* @brief Enable TIMER0_IRQ_0 in the NVIC.
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* @retval None
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*/
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static void _timer_enable_nvic(void)
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{
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*NVIC_ISER0 = (1U << TIMER0_ALARM0_IRQ);
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}
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/**
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* @brief Arm alarm 0 with the next target time.
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* @retval None
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*/
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static void _timer_arm_alarm(void)
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{
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uint32_t target;
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target = TIMER0->TIMERAWL + _alarm_period_us;
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TIMER0->ALARM0 = target;
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}
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void timer_release_reset(void)
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{
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_timer_clear_reset_bit();
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_timer_wait_reset_done();
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}
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void timer_tick_init(void)
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{
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_timer_set_tick_cycles();
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_timer_enable_tick();
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}
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void timer_alarm_start(uint32_t period_ms, timer_callback_t cb)
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{
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_user_callback = cb;
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_alarm_period_us = period_ms * 1000U;
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_timer_enable_alarm_irq();
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_timer_enable_nvic();
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_timer_arm_alarm();
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}
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/**
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* @brief TIMER0 alarm 0 interrupt handler (exception 16 + IRQ 0).
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* @retval None
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*/
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void TIMER0_IRQ_0_Handler(void)
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{
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TIMER0->INTR = TIMER_INTR_ALARM0_MASK;
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_timer_arm_alarm();
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if (_user_callback)
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_user_callback();
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}
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