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89 lines
1.3 KiB
89 lines
1.3 KiB
#include <common.h>
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#include <gpio.h>
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#include <systick.h>
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static void init_gpios(void)
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{
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gpio_enable(GPIOA);
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gpio_enable(GPIOB);
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gpio_enable(GPIOC);
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gpio_set_mode(GPIOC, BIT8 | BIT9, MODER_OUTPUT);
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}
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static void init_clock(void)
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{
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// Flash timing - 64-bit access, pre-fetch, latency = 1
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FLASH_ACR |= FLASH_ACR_ACC64; // Cannot write both at once
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FLASH_ACR |= FLASH_ACR_PRFTEN | FLASH_ACR_LATENCY;
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// Power on HSI (runs from MSI on start)
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RCC_CR |= RCC_CR_HSION;
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// Wait for HSIRDY
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while (!(RCC_CR & RCC_CR_HSIRDY));
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// Select HSI as the core clock source
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RCC_CFGR &= ~RCC_CFGR_SW;
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RCC_CFGR |= RCC_CFGR_SW_HSI;
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}
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static void init_usart(void)
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{
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gpio_set_af(GPIOC, BIT10 | BIT11, AF7);
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// USART at C11, C12
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RCC_APB1ENR |= RCC_APB1ENR_USART3EN;
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// RATE 9600Bd 104.1875 (see datasheet for reference)8.6875
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// 0x00683 ... 9600
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USART3_BRR = 0x0008A; // 115200
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// USART enable
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USART3_CR1 = USART_CR1_UE | USART_CR1_RE | USART_CR1_TE;
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}
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/** Called before main() */
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void SystemInit(void)
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{
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init_clock();
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systick_setup(16000);
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init_gpios();
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init_usart();
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}
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static uint32_t time = 0;
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/** IRQ */
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void SysTick_Handler(void)
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{
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time++;
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if (time == 500) {
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time = 0;
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GPIOC_ODR ^= BIT9;
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}
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}
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void delay(void)
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{
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for (int i = 0; i < 100000; i++) {
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__asm__("nop");
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}
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}
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int main(void)
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{
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while (1) {
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delay();
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GPIOC_ODR ^= BIT8;
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}
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}
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