regarding Sleep Mode of nRF51

Question

Hi. I'm using PCA10028, SDK10.0.0 S130.

I want to make nRF51 goes sleep mode. So I tested linked source code as below. github.com/.../main.c

It works well. But after I add this code in "ble_app_hrs_c" as below, it doesn't work.

int main(void) {

bool erase_bonds;

// Initialize.
APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, NULL);
buttons_leds_init(&erase_bonds);
uart_init();
printf("Heart rate collector example\r\n");
ble_stack_init();
device_manager_init(erase_bonds);
db_discovery_init();
hrs_c_init();
bas_c_init();

// Start scanning for peripherals and initiate connection
// with devices that advertise Heart Rate UUID.
scan_start();


// Configure BUTTON1 as a regular input 
  nrf_gpio_cfg_input(BUTTON_1, NRF_GPIO_PIN_NOPULL); 
   
  // Configure BUTTON2 with SENSE enabled  
  nrf_gpio_cfg_sense_input(BUTTON_2, NRF_GPIO_PIN_NOPULL, NRF_GPIO_PIN_SENSE_LOW); 
   
  // Configure the LED pins as outputs 
  nrf_gpio_range_cfg_output(LED_START, LED_STOP); 
   
  nrf_gpio_pin_set(LED_1); 
   
  // If desired, change the RAM retention parameters: 
  NRF_POWER->RAMON = POWER_RAMON_ONRAM0_RAM0On	 << POWER_RAMON_ONRAM0_Pos 
				   | POWER_RAMON_ONRAM1_RAM1On	 << POWER_RAMON_ONRAM1_Pos 
				   | POWER_RAMON_OFFRAM0_RAM0Off << POWER_RAMON_OFFRAM0_Pos 
				   | POWER_RAMON_OFFRAM1_RAM1Off << POWER_RAMON_OFFRAM1_Pos; 
   
  while(1) 
  { 	 
	  // If BUTTON1 is pressed.. 
	  if(nrf_gpio_pin_read(BUTTON_1) == 0) 
	  { 
		  // Clear LED1
		  nrf_gpio_pin_clear(LED_1); 


		  // Enter system OFF. After wakeup the chip will be reset, and the MCU will run from the top  
		  NRF_POWER->SYSTEMOFF = 1; 
	  } 
  }

Q1. It doesn't go to "nrf_gpio_pin_read(BUTTON_1) == 0", although i press the button.

Q2. If I want to use Only advertising or scanning, I can make other blocks go to sleep mode. Could you give me the way of that? Like example code or advice?

I hope your reply.

FormerMember · Accepted Answer

Q1) When the BSP library is included in the project, I would recommend you to not use the buttons used by that library, button 1 and 2. BSP is by default included in the projects in the SDK. As you can see in the BSP documentation , button 1 will put the chip to sleep. If you change the button that triggers the system OFF mode to button 3 or 4 you will see that it works. 
 When using the softdevice, and want to put the chip to system OFF, you should use the function sd_power_system_off(..) . 
 The same would be for the RAM on/off register; use sd_power_ramon_set(..)/get(..)/clr(..) . 
 As you may know, the LEDs are "inverted" on the nRF51-DK. It means that nrf_gpio_pin_clear(LED) will turn the LED on. 
 Q2) sd_power_system_off(..)/ NRF_POWER->SYSTEMOFF = 1 will put the chip to system OFF. When the chip wakes up, the chip will be reset, see the nRF51 Series Reference Manual, chapter 12.1.5. 
 If you want the chip to sleep between the advertising/scanning events, you should use sd_app_evt_wait(..) . All SDK examples do this using power_manage(). 
 For your reference, I have attached a modified version of your code that sets the chip in system OFF when pushing button 3: 
 int main(void)
{
 bool erase_bonds;
 uint32_t err_code;

 // Initialize.
 APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, NULL);
 buttons_leds_init(&erase_bonds);
 nrf_log_init();
 APPL_LOG("Heart rate collector example
");
 ble_stack_init();
 device_manager_init(erase_bonds);
 db_discovery_init();
 hrs_c_init();
 bas_c_init();
	
 // Configure BUTTON1 as a regular input 
 nrf_gpio_cfg_input(BUTTON_3, NRF_GPIO_PIN_PULLUP); 
 
 // Configure BUTTON2 with SENSE enabled 
 nrf_gpio_cfg_sense_input(BUTTON_4, NRF_GPIO_PIN_NOPULL, NRF_GPIO_PIN_SENSE_LOW); 
 
 // Configure the LED pins as outputs 
 nrf_gpio_range_cfg_output(LED_START, LED_STOP); 

 scan_start();
 
 nrf_gpio_pin_clear(LED_3); // todo
 nrf_gpio_pin_set(LED_4);
 
 for (;; )
 {
 // If BUTTON1 is pressed.. 
 if(nrf_gpio_pin_read(BUTTON_3) == 0) 
 { 
 // Clear LED1
 nrf_gpio_pin_toggle(LED_4); 
 // Enter system OFF. After wakeup the chip will be reset, and the MCU will run from the top 
 err_code = sd_power_system_off();
 APP_ERROR_CHECK(err_code);
 //NRF_POWER->SYSTEMOFF = 1; 
 } 
 }
}