/*
  ARM Cortex M4 assembler subroutine example "blinky" 

  14_02_2021 chris

  thanks to sAlexander for LED control
  https://github.com/sAlexander/nrf52-minimal-c/blob/master/main.c
*/


#include <stdint.h>

#define LED_1 13

// Defined in "GPIO" for the nrf52.
#define CFG_MODE_ON 3
#define LED_1_PIN_CNF_PTR  (*((volatile unsigned long*) (0x50000000 + 0x700 + LED_1 * 4)))

#define SET_PTR (*((volatile unsigned long*) (0x50000000 + 0x508)))
#define CLR_PTR (*((volatile unsigned long*) (0x50000000 + 0x50C)))

extern void asmDelay(uint32_t);

#define DELAY_MS 1000

int main(void) 
{

  LED_1_PIN_CNF_PTR = CFG_MODE_ON;
  
  while(1)
  {
    SET_PTR = (1 << LED_1);
    asmDelay(DELAY_MS);
    CLR_PTR = (1 << LED_1);
    asmDelay(DELAY_MS);
  }
}