I can not re-program the nrf51822. Why?

Question

I have uploaded the following code, but I can not re-program the next.



#define AREF0						0
#define AIN3						2
#define AIN4						3


int main(void)
	{
// Start 16 MHz crystal oscillator 
  NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
  NRF_CLOCK->TASKS_HFCLKSTART = 1;

  // Wait for the external oscillator to start up 
  while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0) 
  {
  }
  
  
NRF_GPIO->PIN_CNF[AREF0] = (GPIO_PIN_CNF_SENSE_Low << GPIO_PIN_CNF_SENSE_Pos) | 
								(GPIO_PIN_CNF_DRIVE_S0S1 << GPIO_PIN_CNF_DRIVE_Pos) | 
								(GPIO_PIN_CNF_PULL_Pullup << GPIO_PIN_CNF_PULL_Pos) | 
								(GPIO_PIN_CNF_INPUT_Connect << GPIO_PIN_CNF_INPUT_Pos) | 
								(GPIO_PIN_CNF_DIR_Input << GPIO_PIN_CNF_DIR_Pos);
	
	
	//nrf_gpio_cfg_output(AREF0);
	nrf_gpio_cfg_output(AIN3);
	nrf_gpio_cfg_output(AIN4);
	
	NRF_GPIOTE->INTENSET=GPIOTE_INTENSET_PORT_Msk;

	flag_TIM0.OVF_10ms=0;


	//GO_SLEEP;
	NRF_POWER->SYSTEMOFF = 1;
	
	
	while(true)
		{

		TogglePin_us(20, AIN3);

		}
	}

Thanks Peter

Hung Bui · Accepted Answer

Hi Peter, 
 You need to wake the chip up before you can program it. The programmer can not wake it up when it entered System off mode. 
 What you can do is to use nRGo Studio to recover the chip, you should be able to program it again after that.