32 lines
874 B
C
32 lines
874 B
C
#include <stdint.h>
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#include <stm32f4xx.h>
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int main(void)
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{
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// GPIO Port D Clock Enable
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RCC->AHB1ENR = RCC_AHB1ENR_GPIODEN;
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// GPIO Port D Pin 15 down to 12 Push/Pull Output
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GPIOD->MODER = GPIO_MODER_MODER12_0
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| GPIO_MODER_MODER13_0
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| GPIO_MODER_MODER14_0
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| GPIO_MODER_MODER15_0;
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// Set green and red LEDs
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GPIOD->ODR = GPIO_ODR_OD12 | GPIO_ODR_OD14;
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// SysTick enable with clk source to AHB/8
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SysTick->CTRL = SysTick_CTRL_ENABLE_Msk;
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SysTick->LOAD = 1000000; // 16 MHz / 8 / 2 Hz
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// Do forever:
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while (1)
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{
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// Wait a moment
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while ((SysTick->CTRL & (1 << 16)) == 0);
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// Flip all LEDs
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GPIOD->ODR ^= GPIO_ODR_OD12
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| GPIO_ODR_OD13
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| GPIO_ODR_OD14
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| GPIO_ODR_OD15;
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}
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}
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