nrf52 RAM Retention issue

[vishal]

Hi, In my project i would like to save 100 bytes of information in RAM before going to System-off sleep mode.I have tested the example project given in sdk11 works okay.Have used the same in my application as well.I am using softdevice S132 .Configured a button to wake up. My issue begins here :-( -After programming my board I used the push button to wake my device,the RAM data was available and works perfectly.But if I power cycle the board once,and after my device sleeps if I wake my device by pressing the push button the RAM details are not read.But what I noticed is the register GPREGRET was written to and read as expected.

-Should i take any special care while saving data to RAM?

[vishal]

// This pin is used for waking up from System OFF and is active low, enabling sense capabilities. nrf_gpio_cfg_sense_input(PIN_GPIO_WAKEUP, BUTTON_PULL, NRF_GPIO_PIN_SENSE_LOW); nrf_delay_ms(1);

			 if ((NRF_POWER->GPREGRET >> 4) == RESET_MEMORY_TEST_BYTE)
	{
			// Take the loop_count value.
		 
			NRF_POWER->GPREGRET = 0;

		
		 // clear GPREGRET register before exit.
		 NRF_POWER->GPREGRET = 0;
					


			if (*p_ram_test != RAM_MEMORY_TEST_WORD)
			{
					printf("Read Failed\r\n");
			}
			else{
				 printf("Read Success\n");
			}

			*p_ram_test = 0;
	}else{
		printf("RESET\r\n");
	}

	// Write the known sequence + loop_count to the GPREGRET register.

	NRF_POWER->GPREGRET = ((RESET_MEMORY_TEST_BYTE << 4));

	// Write the known value to the known address in RAM, enable RAM retention, set System OFF, and wait
	// for GPIO wakeup from external source.

	//LEDS_ON(1 << READY_PIN_NUMBER);
	nrf_delay_ms(1000);

	// Switch on both RAM banks when in System OFF mode.
	NRF_POWER->RAMON |= POWER_RAMON_ONRAM0_RAM0On << POWER_RAMON_ONRAM0_Pos
		| POWER_RAMON_ONRAM1_RAM1On << POWER_RAMON_ONRAM1_Pos
		| POWER_RAMON_OFFRAM0_RAM0On << POWER_RAMON_OFFRAM0_Pos
		| POWER_RAMON_OFFRAM1_RAM1On << POWER_RAMON_OFFRAM1_Pos;

	// Write test word to RAM memory.
	*p_ram_test = RAM_MEMORY_TEST_WORD;
		
		 printf("\r\nSleep: \r\n");
		  nrf_delay_ms(10);
	// Enter System OFF and wait for wake up from GPIO detect signal.
	NRF_POWER->SYSTEMOFF = 0x1;
	// Use data synchronization barrier and a delay to ensure that no failure
	// indication occurs before System OFF is actually entered.
	__DSB();
	__NOP();
	printf("\r\nStart: \r\n");