Problems with sd_ble_gattc_write()

Question

Hello everyone,

I used the Multirole example as base for my code. My target is to make a communication with two NRF52382. I changed the HRS (heart rate servide) to my custom service and custom characteristic. After that I implemented the function sd_ble_gattc_read to the code and this also works. The Central is able to read out the characteristic data (500 bytes) of the Peripheral.

My next target is now to write into the characteristic with the function sd_ble_gattc_write(). My MAX_MTU_SIZE is 103 therefore I checked the MSC for the usage of sd_ble_gattc_write. I made it really similar to the read function, but I get always the err_code =1 which is SVC Handler is Missing. I am not 100% sure what this means and what could cause this problem. As handler for the write function I used the same one like in the read.

void ble_hrs_c_local_data_write(ble_hrs_c_t const *p_ble_hrs_c)
{     

      ble_gattc_write_params_t write_params;
      ret_code_t             err_code;
      uint8_t writestatus = 0;

      uint8_t data_write_one[100];
      uint8_t data_write_two[100];
      uint8_t data_write_three[100];
      uint8_t data_write_four[100];
      uint8_t data_write_five[100];

      for(int i = 0; i<=99; i++)
      {
        data_write_one[i]= 57;
        data_write_two[i]= 57;
        data_write_three[i]= 57;
        data_write_four[i]= 57;
        data_write_five[i]= 57;
        //Data of the own characteristic ist here: hrs_init_params.data
        // Data split into parts
      }

      nrf_delay_ms(300);
        
      write_params.len = 100;
      write_params.offset = 0;
   //  write_params.flags = BLE_GATT_EXEC_WRITE_FLAG_PREPARED_WRITE;
       write_params.handle = p_ble_hrs_c->peer_hrs_db.hrm_handle;


       for(int i = 0; i<=5; i++)
       { 
      write_params.write_op = BLE_GATT_OP_PREP_WRITE_REQ;

      switch (writestatus)
      {
      case 0:
      write_params.p_value = &data_write_one[100];
      break;
      case 1:
      write_params.p_value = &data_write_two[100];
      break;
            case 2:
      write_params.p_value = &data_write_three[100];
      break;
            case 3:
      write_params.p_value = &data_write_four[100];
      break;
            case 4:
      write_params.p_value = &data_write_five[100];
      break;
       case 5:
      write_params.write_op = BLE_GATT_OP_EXEC_WRITE_REQ;
      write_params.flags = BLE_GATT_EXEC_WRITE_FLAG_PREPARED_WRITE;
      break;
      }
      err_code = sd_ble_gattc_write(p_ble_hrs_c->conn_handle,&write_params);
      
      if(err_code=!0)
      {
      nrf_delay_ms(500);
      
      }
      APP_ERROR_CHECK(err_code);
      
      write_params.offset=write_params.offset+100;
      writestatus= writestatus+1;
      nrf_delay_ms(300);
      }
}

Currently I work with delays because I hadn´t time yet to understand and implement the QWR. Can you also give me some hints how I can improve this?

If you need more Information from the code please inform me. I think I overseen something but I am not able to find it. I hope you guys can help me.

Best regards

Hani