mirror of
https://github.com/eddyem/stm32samples.git
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44 lines
1.7 KiB
C
44 lines
1.7 KiB
C
/*
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* This file is part of the usart project.
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* Copyright 2026 Edward V. Emelianov <edward.emelianoff@gmail.com>.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stm32g4.h>
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#include "hardware.h"
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volatile uint32_t Tms = 0;
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/* Called when systick fires */
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void sys_tick_handler(){
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++Tms;
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}
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void gpio_setup(){
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RCC->AHB2ENR = RCC_AHB2ENR_GPIOAEN | RCC_AHB2ENR_GPIOCEN; // enable PC & PA (USART1)
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__DSB(); // Data Synchronization Barrier - wait until data will be really written to AHB2ENR
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// set PC6 as push-pull output, PC13 is pulldown input, other as default (AIN)
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GPIOC->MODER = (0xffffffff & ~(GPIO_MODER_MODE6 | GPIO_MODER_MODE13)) | MODER_O(6) | MODER_I(13);
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GPIOC->PUPDR = PUPD_PD(13); // pulldown
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GPIOC->OTYPER = OTYPER_PP(6); // push-pull (default)
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// PA9 (Tx) and PA10 (Rx) (don't forget about SWDIO)
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GPIOA->MODER = (0xabffffff & ~(GPIO_MODER_MODE9 | GPIO_MODER_MODE10)) | MODER_AF(9) | MODER_AF(10);
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GPIOA->AFR[1] = AFRf(7, 9) | AFRf(7, 10); // SWDIO is 0 by default; USART1 is AF7
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// count milliseconds
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SysTick_Config(SysFreq / 1000); // arg should be < 0xffffff
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}
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