58 lines
2.3 KiB
C
58 lines
2.3 KiB
C
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/* firmware template for STM8S microcontroller
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* Copyright (C) 2019-2020 King Kévin <kingkevin@cuvoodoo.info>
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* SPDX-License-Identifier: GPL-3.0-or-later
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*/
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#include <stdint.h>
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#include <stdbool.h>
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#include "stm8s.h"
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// get length of array
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#define ARRAY_LENGTH(x) (sizeof(x) / sizeof((x)[0]))
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// blocking wait (in 10 us steps, up to UINT32_MAX / 10)
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static void wait_10us(uint32_t us10)
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{
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us10 = ((us10 / (1 << CLK->CKDIVR.fields.HSIDIV)) * 1000) / 206; // calibrated for 1 ms
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for (volatile uint32_t t = 0; t < us10; t++); // burn energy
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}
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void main(void)
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{
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sim(); // disable interrupts (while we reconfigure them)
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CLK->CKDIVR.fields.HSIDIV = CLK_CKDIVR_HSIDIV_DIV0; // don't divide internal 16 MHz clock
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CLK->CKDIVR.fields.CPUDIV = CLK_CKDIVR_CPUDIV_DIV0; // don't divide CPU frequency to 16 MHz
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while (!CLK->ICKR.fields.HSIRDY); // wait for internal oscillator to be ready
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// configure auto-wakeup (AWU) to be able to refresh the watchdog
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// 128 kHz LSI used by default in option bytes CKAWUSEL
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// we skip measuring the LS clock frequency since there is no need to be precise
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AWU->TBR.fields.AWUTB = 10; // interval range: 128-256 ms
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AWU->APR.fields.APR = 0x3e; // set time to 256 ms
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AWU_CSR |= AWU_CSR_AWUEN; // enable AWU (start only when entering wait or active halt mode)
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// configure independent watchdog (very loose, just it case the firmware hangs)
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IWDG->KR.fields.KEY = IWDG_KR_KEY_REFRESH; // reset watchdog
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IWDG->KR.fields.KEY = IWDG_KR_KEY_ENABLE; // start watchdog
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IWDG->KR.fields.KEY = IWDG_KR_KEY_ACCESS; // allows changing the prescale
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IWDG->PR.fields.PR = IWDG_PR_DIV256; // set prescale to longest time (1.02s)
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IWDG->KR.fields.KEY = IWDG_KR_KEY_REFRESH; // reset watchdog
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rim(); // re-enable interrupts
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bool action = false; // if an action has been performed
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while (true) {
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IWDG_KR = IWDG_KR_KEY_REFRESH; // reset watchdog
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if (action) { // something has been performed, check if other flags have been set meanwhile
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action = false; // clear flag
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} else { // nothing down
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wfi(); // go to sleep (wait for any interrupt, including periodic AWU)
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}
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}
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}
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void awu(void) __interrupt(IRQ_AWU) // auto wakeup
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{
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volatile uint8_t awuf = AWU_CSR; // clear interrupt flag by reading it (reading is required, and volatile prevents compiler optimization)
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// let the main loop kick the dog
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}
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