How store large amount data 73Kbytes into flash using FDS?

Question

We are using nRF52840 with sdk 15.0 version & segger embedded studio. We are able to store some small amount of configuration data into flash using FDS. But now we want to store large data array near about 73Kbytes into flash. I am writing example code for storing this data and created one dummy array of size 73728 bytes. But I getting following ERROR: 
 FDS_ERR_RECORD_TOO_LARGE 
 I am confused for configuration of FDS for storing 73Kbytes 
 Here is bellow edited in sdk_config.h 
 FDS_VIRTUAL_PAGES 10 
 FDS_VIRTUAL_PAGE_SIZE 2048 
 FDS_OP_QUEUE_SIZE 4 
 Will you please help me how i use this above configuration for storing 73KB data. & how i fixed FDS_ERR_RECORD_TOO_LARGE ERROR? 
 Is it possible to store this data in one fds_record_write (...) call request? 
 Thanks in advanced..!!

vishal · Accepted Answer

Yes you are right, we are not writing all data 74KB at once. We have write with 4068 bytes of chunk data in to flash memory. Also successfully write into flash here is our below function: Will you please review this function and is it correct way... 
 ret_code_t fds_reading_write(uint16_t file_ID, uint8_t const *data_to_write, const uint32_t data_length) {
 uint32_t fds_write_counter = data_length;
 ret_code_t err_code;
 fds_record_t record;
 for (uint16_t pages = 1; pages < 20; pages++) {
 fds_record_desc_t record_desc = {0};
 fds_find_token_t ftoken;
 memset(&ftoken, 0x00, sizeof(fds_find_token_t));
 memset(&record_desc, 0x00, sizeof(fds_record_desc_t));
 // Set up record.
 record.file_id = file_ID;
 record.key = pages;
 if (fds_write_counter < LENGTH_TO_SEND) {
 record.data.length_words = ((fds_write_counter + 3) / sizeof(uint32_t));
 } else {
 record.data.length_words = ((LENGTH_TO_SEND + 3) / sizeof(uint32_t));
 }
 record.data.p_data = &data_to_write[DATA_STORE_LEN - fds_write_counter]; //DATA_STORE_LEN = 74000
 err_code = fds_record_write(&record_desc, &record);
 APP_ERROR_CHECK(err_code);
 wait_for_next_write();
 if (err_code == FDS_SUCCESS) {
 NRF_LOG_DEBUG("Write Sucess:%d", fds_write_counter);
 if (fds_write_counter < LENGTH_TO_SEND) {
 fds_write_counter = 0;
 free((uint8_t *)data_to_write);
 } else {
 fds_write_counter -= LENGTH_TO_SEND;
 }
 } else {
 NRF_LOG_DEBUG("Write Failed, id %d", err_code);
 }
 }
 return NRF_SUCCESS;
} 
 Thanks for your great supporting..!!

Einar Thorsrud · Answer

Hi, 
 I am missing the whole picture, this looks OK. It seems like you have a buffer containing the whole 74 kB (pointed to by data_to_write), and you do separate writes until it succeeds. I want to mention that this function must run in a low priority (typically main context), so that the event indicating that write operation is successful can run, which I assume updates some state variable or similar used by your wait_for_next_write() function. Assuming that is OK, it should work. 
 (As a side note I do not personally like that you call free inside this write function when you have written the last chunk, as it is not obvious for the caller code that calling this function would eventually free the input buffer).

How store large amount data 73Kbytes into flash using FDS?

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