kopia lustrzana https://github.com/SP8EBC/ParaTNC
98 wiersze
2.4 KiB
C
98 wiersze
2.4 KiB
C
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/*
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* pwr_save.c
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*
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* Created on: Aug 22, 2021
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* Author: mateusz
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*/
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#include "pwr_save.h"
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#include "stm32l4xx.h"
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#include <stdint.h>
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#define IN_STOP2_MODE (1 << 1)
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#if defined(STM32L471xx)
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/**
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* This function initializes everything related to power saving features
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* including programming Flash memory option bytes
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*/
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void pwr_save_init(void) {
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// make a pointer to option byte
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uint32_t* option_byte = (uint32_t*)0x1FFF7800;
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// content of option byte read from the flash memory
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uint32_t option_byte_content = *option_byte;
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// definition of bitmask
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#define IWDG_STBY_STOP (0x3 << 17)
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// check if IWDG_STDBY and IWDG_STOP is not set in ''User and read protection option bytes''
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// at 0x1FFF7800
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if ((option_byte_content & IWDG_STBY_STOP) == IWDG_STBY_STOP) {
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// unlock write/erase operations on flash memory
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FLASH->KEYR = 0x45670123;
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FLASH->KEYR = 0xCDEF89AB;
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// wait for any possible flash operation to finish (rather impossible here, but ST manual recommend doing this)
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while((FLASH->SR & FLASH_SR_BSY) != 0);
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// unlock operations on option bytes
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FLASH->OPTKEYR = 0x08192A3B;
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FLASH->OPTKEYR = 0x4C5D6E7F;
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// set the flash option register (in RAM!!)
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FLASH->OPTR &= (0xFFFFFFFF ^ (FLASH_OPTR_IWDG_STDBY | FLASH_OPTR_IWDG_STOP));
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// trigger an update of flash option bytes with values from RAM (from FLASH->OPTR)
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FLASH->CR |= FLASH_CR_OPTSTRT;
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// wait for option bytes to be updated
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while((FLASH->SR & FLASH_SR_BSY) != 0);
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// lock flash memory
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FLASH-> CR |= FLASH_CR_LOCK;
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// forcre reloading option bytes
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FLASH->CR |= FLASH_CR_OBL_LAUNCH;
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}
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}
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/**
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* Entering STOP2 power save mode. In this mode all clocks except LSI and LSE are disabled. StaticRAM content
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* is preserved, optionally GPIO and few other peripherals can be kept power up depending on configuration
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*/
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void pwr_save_enter_stop2(void) {
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// clear previous low power mode selection
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PWR->CR1 &= (0xFFFFFFFF ^ PWR_CR1_LPMS_Msk);
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// select STOP2
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PWR->CR1 |= PWR_CR1_LPMS_STOP2;
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// enable write access to RTC registers by writing two magic words
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RTC->WPR = 0xCA;
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RTC->WPR = 0x53;
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// save an information that STOP2 mode has been applied
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RTC->BKP4R |= IN_STOP2_MODE;
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SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk;
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DBGMCU->CR &= (0xFFFFFFFF ^ (DBGMCU_CR_DBG_SLEEP_Msk | DBGMCU_CR_DBG_STOP_Msk | DBGMCU_CR_DBG_STANDBY_Msk));
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// disabling all IRQs
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__disable_irq();
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asm ("wfe");
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}
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#endif
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