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]

#define RESET_MEMORY_TEST_BYTE (0x0DUL) #define SIZE_OF_RAM_RETENTION_BUFFER 100 #define DEAD_BEEF 0xDEADBEEF static uint32_t ram_retention_data[SIZE_OF_RAM_RETENTION_BUFFER];

void dot_boot_up() {

	uint32_t p_ramon[1], err_code, i, verification_data;

	err_code = sd_power_gpregret_get(p_ramon);
	APP_ERROR_CHECK(error_code);

	uint32_t * volatile p_ram_test = (uint32_t *) VARIANCE_DATA_ADDRESS;
	
	//Check For power Cycle
	if ((p_ramon[0] >> 4) == RESET_MEMORY_TEST_BYTE) {

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

		memset(&ram_retention_data, 0, sizeof(SIZE_OF_RAM_RETENTION_BUFFER));
		verification_data = 0;
		for (i = 0; i < SIZE_OF_RAM_RETENTION_BUFFER; i++) {
			//Read Data From RAM Location
			ram_retention_data[i] = *p_ram_test;
			*p_ram_test = 0;


			p_ram_test += 0x1;

		}


		verification_data |= ((uint8_t) ram_retention_data[INDEX_OF_VER_BYTE_0])
		<< 24;
		verification_data |= ((uint8_t) ram_retention_data[INDEX_OF_VER_BYTE_1])
		<< 16;
		verification_data |= ((uint8_t) ram_retention_data[INDEX_OF_VER_BYTE_2])
		<< 8;
		verification_data |=
		((uint8_t) ram_retention_data[INDEX_OF_VER_BYTE_3]);

		if (verification_data != DEAD_BEEF) { //check for data corruption by comparing to know seqence of data

			dprint("RAM Read Failed\r\n");

			memset(&ram_retention_data, 0,
				sizeof(SIZE_OF_RAM_RETENTION_BUFFER));
			ram_retention_data[INDEX_OF_VER_BYTE_0] = (uint8_t) ((DEAD_BEEF
				>> 24) & 0xFF);
			ram_retention_data[INDEX_OF_VER_BYTE_1] = (uint8_t) ((DEAD_BEEF
				>> 16) & 0xFF);
			ram_retention_data[INDEX_OF_VER_BYTE_2] =
			(uint8_t) ((DEAD_BEEF >> 8) & 0xFF);
			ram_retention_data[INDEX_OF_VER_BYTE_3] = (uint8_t) (DEAD_BEEF
				& 0xFF);

		} else {

			
			dprint("Success");

		}

		err_code = sd_power_gpregret_clr(0x0);
		APP_ERROR_CHECK(err_code);

	} else {
		dprint("Device Reset/Corruption\r\n");
		memset(&ram_retention_data, 0, sizeof(SIZE_OF_RAM_RETENTION_BUFFER));
		ram_retention_data[INDEX_OF_VER_BYTE_0] = (uint8_t) ((DEAD_BEEF >> 24)
			& 0xFF);
		ram_retention_data[INDEX_OF_VER_BYTE_1] = (uint8_t) ((DEAD_BEEF >> 16)
			& 0xFF);
		ram_retention_data[INDEX_OF_VER_BYTE_2] = (uint8_t) ((DEAD_BEEF >> 8)
			& 0xFF);
		ram_retention_data[INDEX_OF_VER_BYTE_3] = (uint8_t) (DEAD_BEEF & 0xFF);

	}
}


void dot_enter_sleep(void) {

	uint32_t * volatile p_ram_test = (uint32_t *) VARIANCE_DATA_ADDRESS;
	uint32_t err_code, i = 0;
	uint32_t ramon = 0;


	nrf_gpio_cfg_sense_input(16, NRF_GPIO_PIN_PULLUP, NRF_GPIO_PIN_SENSE_LOW);

	nrf_delay_ms(1);
	for (i = 0; i < SIZE_OF_RAM_RETENTION_BUFFER; i++) {

		*p_ram_test = 0;// Clear RAM Locations

		p_ram_test += 0x1;
	}

	p_ram_test = (uint32_t *) VARIANCE_DATA_ADDRESS;//Resest Address

	err_code = sd_power_gpregret_set((RESET_MEMORY_TEST_BYTE << 4));
	APP_ERROR_CHECK(err_code);
	nrf_delay_ms(1);

	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;


	err_code = sd_power_ramon_set(ramon);
	APP_ERROR_CHECK(err_code);

	p_ram_test = (uint32_t *) VARIANCE_DATA_ADDRESS;
	
	for (i = 0; i < SIZE_OF_RAM_RETENTION_BUFFER; i++) {

		
		*p_ram_test = 0xAA; //Test Dummy Value
		nrf_delay_ms(1);



	}
	
	
	
	__DSB();

	dprint("Sleep\r\n");

	nrf_delay_ms(10);
	sd_power_system_off();

	dprint("Sleep error\r\n");

}