33 lines
913 B
C
33 lines
913 B
C
#include <stdint.h>
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#define RCC_AHB1ENR_BIT_GPIODEN *(volatile uint32_t*)(0x42000000 + 0x00023830 * 32 + 3 * 4)
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#define GPIOD_BASE 0x40020C00
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#define GPIOD_MODER *(volatile uint32_t*)(GPIOD_BASE + 0x00)
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#define GPIOD_ODR *(volatile uint32_t*)(GPIOD_BASE + 0x14)
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#define STK_CTRL *(volatile uint32_t*)(0xE000E010)
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#define STK_LOAD *(volatile uint32_t*)(0xE000E014)
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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_BIT_GPIODEN = 1;
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// GPIO Port D Pin 15 down to 12 Push/Pull Output
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GPIOD_MODER = 0x55000000;
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// Set green and red LEDs
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GPIOD_ODR = 0x5000;
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// SysTick enable with clk source to AHB/8
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// (AHB is by default HSI; 16 MHz/8)
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STK_CTRL = 1;
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STK_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 ((STK_CTRL & (1 << 16)) == 0);
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// Flip all LEDs
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GPIOD_ODR ^= 0xF000;
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}
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}
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