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53 lines
1.6 KiB
53 lines
1.6 KiB
6 years ago
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/* LED blink project for the STM32L031 */
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#include "stm32l031xx.h"
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volatile unsigned long SysTickCount = 0;
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void __attribute__ ((interrupt, used)) SysTick_Handler(void)
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{
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SysTickCount++;
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switch ( SysTickCount & 3 )
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{
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case 0:
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GPIOA->BSRR = GPIO_BSRR_BS_13; /* atomic set PA13 */
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break;
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case 1:
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GPIOA->BSRR = GPIO_BSRR_BR_13; /* atomic clr PA13 */
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break;
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case 2:
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GPIOA->BSRR = GPIO_BSRR_BS_14; /* atomic set PA13 */
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break;
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case 3:
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GPIOA->BSRR = GPIO_BSRR_BR_14; /* atomic clr PA13 */
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break;
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}
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}
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int main()
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{
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RCC->IOPENR |= RCC_IOPENR_IOPAEN; /* Enable clock for GPIO Port A */
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__NOP();
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__NOP();
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GPIOA->MODER &= ~GPIO_MODER_MODE13; /* clear mode for PA13 */
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GPIOA->MODER |= GPIO_MODER_MODE13_0; /* Output mode for PA13 */
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GPIOA->OTYPER &= ~GPIO_OTYPER_OT_13; /* no Push/Pull for PA13 */
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GPIOA->OSPEEDR &= ~GPIO_OSPEEDER_OSPEED13; /* low speed for PA13 */
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GPIOA->PUPDR &= ~GPIO_PUPDR_PUPD13; /* no pullup/pulldown for PA13 */
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GPIOA->BSRR = GPIO_BSRR_BR_13; /* atomic clr PA13 */
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GPIOA->MODER &= ~GPIO_MODER_MODE14; /* clear mode for PA14 */
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GPIOA->MODER |= GPIO_MODER_MODE14_0; /* Output mode for PA14 */
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GPIOA->OTYPER &= ~GPIO_OTYPER_OT_14; /* no Push/Pull for PA14 */
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GPIOA->OSPEEDR &= ~GPIO_OSPEEDER_OSPEED14; /* low speed for PA14 */
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GPIOA->PUPDR &= ~GPIO_PUPDR_PUPD14; /* no pullup/pulldown for PA14 */
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GPIOA->BSRR = GPIO_BSRR_BR_14; /* atomic clr PA14 */
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SysTick->LOAD = 2000*500 - 1;
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SysTick->VAL = 0;
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SysTick->CTRL = 7; /* enable, generate interrupt (SysTick_Handler), do not divide by 2 */
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for(;;)
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;
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}
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