WRITE AND READ SAADC DATA WITH FDS

Question

nrf52832 S132 v6.1.1

i want to write saadc data in flash, so i call "write_to_flash" function in "void saadc_callback(nrf_drv_saadc_evt_t const * p_event)"

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void saadc_callback(nrf_drv_saadc_evt_t const * p_event)
{    
      int product;
        uint16_t val;
      uint8_t value;
      ret_code_t err_code;
      product = channel3_enabled*8 + channel2_enabled*4 + channel1_enabled*2 + channel0_enabled;
    if (p_event->type == NRF_DRV_SAADC_EVT_DONE)
    {
        static uint8_t data_array[SAMPLES_IN_BUFFER*2];
        err_code = nrf_drv_saadc_buffer_convert(p_event->data.done.p_buffer, SAMPLES_IN_BUFFER);
        APP_ERROR_CHECK(err_code);
        uint8_t i;
        printf("\r\nADC event number:%d \r\n", (int)m_adc_evt_counter);
        for (i = 0; i < SAMPLES_IN_BUFFER; i++)
        {
               data_array2[i]=p_event->data.done.p_buffer[i];
                         val = p_event->data.done.p_buffer[i];              
                           printf("%d\r\n",val);                    
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

void saadc_callback(nrf_drv_saadc_evt_t const * p_event)
{    
	  int product;
		uint16_t val;
	  uint8_t value;
	  ret_code_t err_code;
	  product = channel3_enabled*8 + channel2_enabled*4 + channel1_enabled*2 + channel0_enabled;
    if (p_event->type == NRF_DRV_SAADC_EVT_DONE)
    {

        static uint8_t data_array[SAMPLES_IN_BUFFER*2];
        err_code = nrf_drv_saadc_buffer_convert(p_event->data.done.p_buffer, SAMPLES_IN_BUFFER);
        APP_ERROR_CHECK(err_code);

        uint8_t i;
        printf("\r\nADC event number:%d \r\n", (int)m_adc_evt_counter);
        for (i = 0; i < SAMPLES_IN_BUFFER; i++)
        {
               data_array2[i]=p_event->data.done.p_buffer[i];
					     val = p_event->data.done.p_buffer[i];				
						   printf("%d\r\n",val);					
               //8MSB data				
					     value=val>>4;//right shift	4 bit			
					     value |= 1;//XXXX_XXX1,1 means MSB
							 value &= 247;//XXXX_0XX1,0 means saadc data
							 value = dataencode(i, product, value);
					     data_array[(i*2)]=value;
							 value=0;
							 
							 //8LSB data,XXXX_XXX0
							 value=val;
					     value&=254;
					     data_array[i*2+1]=value;
               value=0;
				}
        uint16_t length = (uint16_t)(i*2);
				memcpy(data_array3,data_array,length);
				if(!writeflash_en)
				{err_code = ble_nus_data_send(&m_nus, data_array, &length, m_conn_handle);}
				else
				{write_to_flash();}	
				if ( (err_code != NRF_ERROR_INVALID_STATE) && (err_code != NRF_ERROR_BUSY) && (err_code != NRF_ERROR_NOT_FOUND) )
				{
					APP_ERROR_CHECK(err_code);
				}
        m_adc_evt_counter++;
    }
}


void write_to_flash(void)
{
			fds_record_desc_t desc = {0};
			ret_code_t rc;
			rc = fds_record_write(&desc, &m_dummy_record);
			if(rc == FDS_ERR_NO_SPACE_IN_FLASH)
			{			
				stop_saadc();
				writeflash_en = 0;
				ret_code_t err_code;
				uint16_t length;
				length = 2;
				uint8_t flash_full[2];
				flash_full[0] = 105;
				flash_full[1] = 105;
				err_code = ble_nus_data_send(&m_nus, flash_full, &length, m_conn_handle);
				if ( (err_code != NRF_ERROR_INVALID_STATE) && (err_code != NRF_ERROR_BUSY) && (err_code != NRF_ERROR_NOT_FOUND) )
				{
					APP_ERROR_CHECK(err_code);
				}
				NRF_LOG_INFO("NO SPACE IN FLASH, FDS OPERATION WILL BE OVER")			
			}
			if( rc== FDS_ERR_NO_SPACE_IN_QUEUES)
			{
				writeflash_en = 0;
				stop_saadc();	
				NRF_LOG_INFO("NO SPACE IN QUEUES, FDS OPERATION WILL BE OVER");
			}
		}

sizeof(data_array3) is 240, so every record in flash is 60 words,

virtual page is 3;

virtual page size 1024;

then i stop adc and read data when flash is full, i get 32 records ,every record only contains 16 or 19 or ......words ,less than 60 words.

if everythng is correct, i can get 32 records and 60 words in every record;

the following is my read_from_flash() function

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void read_from_flash()
{
        //±£´æÃØÔ¿µÄÁîÅÆÇåÁã
        fds_find_token_t  tok  = {0};
        ret_code_t rc;
        rc = fds_record_find(CONFIG_FILE, CONFIG_REC_KEY, &desc, &tok);//¶ÔÓ¦KEY¼ÇÂ¼²éÕÒÊý¾Ý
        NRF_LOG_INFO("record_id:%8x",desc.record_id);
        NRF_LOG_INFO("p_record:%8x",desc.p_record);
        if (rc == FDS_SUCCESS)
        {
            /* A config file is in flash. Let's update it. */
            fds_flash_record_t config = {0};
            /* Open the record and read its contents. */
      rc = fds_record_open(&desc, &config);
      APP_ERROR_CHECK(rc);
                                
            NRF_LOG_INFO("Found Record ID = %d",desc.record_id);
            NRF_LOG_INFO("Data = ");
            data = (uint32_t *)config.p_data;
            static uint8_t data_array_send[4];
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

void read_from_flash()
{
		//±£´æÃØÔ¿µÄÁîÅÆÇåÁã
		fds_find_token_t  tok  = {0};
		ret_code_t rc;
		rc = fds_record_find(CONFIG_FILE, CONFIG_REC_KEY, &desc, &tok);//¶ÔÓ¦KEY¼ÇÂ¼²éÕÒÊý¾Ý
		NRF_LOG_INFO("record_id:%8x",desc.record_id);
		NRF_LOG_INFO("p_record:%8x",desc.p_record);
		if (rc == FDS_SUCCESS)
		{
			/* A config file is in flash. Let's update it. */
			fds_flash_record_t config = {0};

			/* Open the record and read its contents. */
      rc = fds_record_open(&desc, &config);
      APP_ERROR_CHECK(rc);
								
			NRF_LOG_INFO("Found Record ID = %d",desc.record_id);
			NRF_LOG_INFO("Data = ");
			data = (uint32_t *)config.p_data;
			static uint8_t data_array_send[4];
			for (uint16_t i=0; i<config.p_header->length_words; i++)//i<config.p_header->length_words(60)
			{
				NRF_LOG_INFO("0x%8x",data[i]);
				data_array_send[0] = data[i];
				data_array_send[1] = data[i]>>8;
				data_array_send[2] = data[i]>>16;
				data_array_send[3] = data[i]>>24;
				uint16_t length1= 4;
				ble_nus_data_send(&m_nus, data_array_send, &length1, m_conn_handle);
			}
			NRF_LOG_INFO("\r\n");
			/* Close the record when done reading. */
			while(fds_record_close(&desc) != FDS_SUCCESS)
			{NRF_LOG_INFO("flash close fail");}	
			while(fds_record_delete(&desc) != FDS_SUCCESS)
			{NRF_LOG_INFO("flash delete fail")}
		}		
		else
		{
			NRF_LOG_INFO("can't find record or no more record to be read");		
			while(app_timer_stop(m_timer_id) != NRF_SUCCESS)
			{NRF_LOG_INFO("stop timer fail");}
			rc = fds_gc();
			if(rc == FDS_SUCCESS)
			{
				NRF_LOG_INFO("GC SUCCESS");
				uint16_t length;
				length = 2;
				uint8_t flash_read_end[2];
				flash_read_end[0] = 121;
				flash_read_end[1] = 121;
				ble_nus_data_send(&m_nus, flash_read_end, &length, m_conn_handle);
			}
			stat();
		}
}

it's called by a timer.

so what's the problem about "read data less than written data" ?

Any suggestion will be appreciated.

tesc · Accepted Answer

Hi, 
 Using flash for buffering data is generally not a good idea, because of the relatively slow speed compared to RAM and because it wears down (10.000 write/erase cycles). 
 Flash is a good idea for persistent data, that is data that must survive a device reset (turning it off and on again.) 
 You should still be able to store data in a buffer in RAM, if you use the 64 kB RAM variant of the nRF52832. Especially so if you move to the nRF52840 with 256 kB RAM. 
 Regards, Terje

WRITE AND READ SAADC DATA WITH FDS

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