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#include <stdint.h>
#include <stdio.h>
#include "stm_misc.h"
#include "stm32f4xx_rcc.h"
#include "stm32f4xx_tim.h"
#include "nlr.h"
#include "misc.h"
#include "mpconfig.h"
#include "parse.h"
#include "obj.h"
#include "runtime.h"
#include "timer.h"
// TIM6 is used as an internal interrup to schedule something at a specific rate
mp_obj_t timer_py_callback;
mp_obj_t timer_py_set_callback(mp_obj_t f) {
timer_py_callback = f;
return mp_const_none;
}
mp_obj_t timer_py_set_period(mp_obj_t period) {
TIM6->ARR = mp_obj_get_int(period) & 0xffff;
return mp_const_none;
}
mp_obj_t timer_py_set_prescaler(mp_obj_t prescaler) {
TIM6->PSC = mp_obj_get_int(prescaler) & 0xffff;
return mp_const_none;
}
mp_obj_t timer_py_get_value(void) {
return mp_obj_new_int(TIM6->CNT & 0xfffff);
}
void timer_init(void) {
timer_py_callback = mp_const_none;
// TIM6 clock enable
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM6, ENABLE);
// Compute the prescaler value so TIM6 runs at 20kHz
uint16_t PrescalerValue = (uint16_t) ((SystemCoreClock / 2) / 20000) - 1;
// Time base configuration
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_TimeBaseStructure.TIM_Period = 20000; // timer cycles at 1Hz
TIM_TimeBaseStructure.TIM_Prescaler = PrescalerValue;
TIM_TimeBaseStructure.TIM_ClockDivision = 0; // unused for TIM6
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; // unused for TIM6
TIM_TimeBaseInit(TIM6, &TIM_TimeBaseStructure);
// enable perhipheral preload register
TIM_ARRPreloadConfig(TIM6, ENABLE);
// enable interrupt when counter overflows
TIM_ITConfig(TIM6, TIM_IT_Update, ENABLE);
// set up interrupt
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_InitStructure.NVIC_IRQChannel = TIM6_DAC_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0f; // lowest priority
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0f; // lowest priority
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
// TIM6 enable counter
TIM_Cmd(TIM6, ENABLE);
// Python interface
mp_obj_t m = mp_obj_new_module(qstr_from_str_static("timer"));
rt_store_attr(m, qstr_from_str_static("callback"), rt_make_function_1(timer_py_set_callback));
rt_store_attr(m, qstr_from_str_static("period"), rt_make_function_1(timer_py_set_period));
rt_store_attr(m, qstr_from_str_static("prescaler"), rt_make_function_1(timer_py_set_prescaler));
rt_store_attr(m, qstr_from_str_static("value"), rt_make_function_0(timer_py_get_value));
rt_store_name(qstr_from_str_static("timer"), m);
}
void timer_interrupt(void) {
if (timer_py_callback != mp_const_none) {
nlr_buf_t nlr;
if (nlr_push(&nlr) == 0) {
// XXX what to do if the GC is in the middle of running??
rt_call_function_0(timer_py_callback);
nlr_pop();
} else {
// uncaught exception
printf("exception in timer interrupt\n");
mp_obj_print((mp_obj_t)nlr.ret_val);
printf("\n");
}
}
}
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