99 lines
3.1 KiB
C
99 lines
3.1 KiB
C
#include <stdint.h>
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#include <stdio.h>
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#include <string.h>
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#include "stm_misc.h"
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#include "stm32f4xx_rcc.h"
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#include "stm32f4xx_tim.h"
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#include "nlr.h"
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#include "misc.h"
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#include "mpconfig.h"
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#include "qstr.h"
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#include "parse.h"
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#include "obj.h"
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#include "runtime.h"
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#include "timer.h"
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// TIM6 is used as an internal interrup to schedule something at a specific rate
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mp_obj_t timer_py_callback;
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mp_obj_t timer_py_set_callback(mp_obj_t f) {
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timer_py_callback = f;
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return mp_const_none;
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}
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mp_obj_t timer_py_set_period(mp_obj_t period) {
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TIM6->ARR = mp_obj_get_int(period) & 0xffff;
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return mp_const_none;
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}
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mp_obj_t timer_py_set_prescaler(mp_obj_t prescaler) {
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TIM6->PSC = mp_obj_get_int(prescaler) & 0xffff;
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return mp_const_none;
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}
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mp_obj_t timer_py_get_value(void) {
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return mp_obj_new_int(TIM6->CNT & 0xfffff);
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}
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void timer_init(void) {
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timer_py_callback = mp_const_none;
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// TIM6 clock enable
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RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM6, ENABLE);
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// Compute the prescaler value so TIM6 runs at 20kHz
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uint16_t PrescalerValue = (uint16_t) ((SystemCoreClock / 2) / 20000) - 1;
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// Time base configuration
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TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
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TIM_TimeBaseStructure.TIM_Period = 20000; // timer cycles at 1Hz
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TIM_TimeBaseStructure.TIM_Prescaler = PrescalerValue;
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TIM_TimeBaseStructure.TIM_ClockDivision = 0; // unused for TIM6
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TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; // unused for TIM6
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TIM_TimeBaseInit(TIM6, &TIM_TimeBaseStructure);
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// enable perhipheral preload register
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TIM_ARRPreloadConfig(TIM6, ENABLE);
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// enable interrupt when counter overflows
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TIM_ITConfig(TIM6, TIM_IT_Update, ENABLE);
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// set up interrupt
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NVIC_InitTypeDef NVIC_InitStructure;
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NVIC_InitStructure.NVIC_IRQChannel = TIM6_DAC_IRQn;
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NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0f; // lowest priority
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NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0f; // lowest priority
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NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
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NVIC_Init(&NVIC_InitStructure);
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// TIM6 enable counter
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TIM_Cmd(TIM6, ENABLE);
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// Python interface
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mp_obj_t m = mp_obj_new_module(QSTR_FROM_STR_STATIC("timer"));
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rt_store_attr(m, QSTR_FROM_STR_STATIC("callback"), rt_make_function_n(1, timer_py_set_callback));
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rt_store_attr(m, QSTR_FROM_STR_STATIC("period"), rt_make_function_n(1, timer_py_set_period));
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rt_store_attr(m, QSTR_FROM_STR_STATIC("prescaler"), rt_make_function_n(1, timer_py_set_prescaler));
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rt_store_attr(m, QSTR_FROM_STR_STATIC("value"), rt_make_function_n(0, timer_py_get_value));
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rt_store_name(QSTR_FROM_STR_STATIC("timer"), m);
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}
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void timer_interrupt(void) {
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if (timer_py_callback != mp_const_none) {
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nlr_buf_t nlr;
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if (nlr_push(&nlr) == 0) {
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// XXX what to do if the GC is in the middle of running??
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rt_call_function_0(timer_py_callback);
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nlr_pop();
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} else {
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// uncaught exception
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printf("exception in timer interrupt\n");
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mp_obj_print((mp_obj_t)nlr.ret_val, PRINT_REPR);
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printf("\n");
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}
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}
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}
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