46 lines
1.3 KiB
C
46 lines
1.3 KiB
C
/* blink.c -- user LED blink
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** Copyright (c) 2020-2021 Renaud Fivet
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*/
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/* Memory locations defined by linker script */
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void __StackTop( void) ; /* __StackTop points after end of stack */
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void Reset_Handler( void) ; /* Entry point for execution */
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/* Interrupt vector table:
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* 1 Stack Pointer reset value
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* 15 System Exceptions
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* NN Device specific Interrupts
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*/
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typedef void (*isr_p)( void) ;
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isr_p const isr_vector[ 2] __attribute__((section(".isr_vector"))) = {
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__StackTop,
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/* System Exceptions */
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Reset_Handler
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} ;
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#define RCC ((volatile long *) 0x40021000)
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#define RCC_AHBENR RCC[ 5]
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#define RCC_AHBENR_IOPBEN 0x00040000 /* 18: I/O port B clock enable */
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#define GPIOB ((volatile long *) 0x48000400)
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#define GPIOB_MODER GPIOB[ 0]
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#define GPIOB_ODR GPIOB[ 5]
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void Reset_Handler( void) {
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int delay ;
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/* User LED ON */
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RCC_AHBENR |= RCC_AHBENR_IOPBEN ; /* Enable IOPB periph */
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GPIOB_MODER |= 1 << (1 * 2) ; /* PB1 Output [01], over default 00 */
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/* OTYPER Push-Pull by default */
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/* PB1 output default LOW at reset */
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/* User LED blink */
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for( ;;) {
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for( delay = 1000000 ; delay ; delay--) ; /* delay between toggling */
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GPIOB_ODR ^= 1 << 1 ; /* toggle PB1 (User LED) */
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}
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}
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/* end of blink.c */
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