sd_ble_gattc_write and error 19

[HuanVH]

Hello,

I need to send a file of about 70KB capacity through BLE. I send each packet as 16 bytes, I get an error 19 after about 10 submissions.
I have read the answers, and I found two ways to solve this. The first is to wait for the BLE_GATTC_EVT_WRITE_CMD_TX_COMPLETE event to send the packet, the second is to check the sd_ble_gattc_write error repeatedly until it succeeds.
Everything was perfect, but the problem happened to me when I sent 4KB. Both error 19 appears, without any BLE_GATTC_EVT_WRITE_CMD_TX_COMPLETE event occurred.
Please help me

Central and peripheral: nRF52832 SDK 15.3 softdevice 6.1.1

[smackenzie]

Looking at the documentation for sd_ble_gattc_write, you will see that NRF_ERROR_RESOURCES (19) is returned if too many writes are performed without responses.

WRITE_CMD can queue up writes internally which is why you are not getting an error immediately.

I think by default its 6, but it can be configured. For example:

static uint32_t set_write_cmd_tx_queue_size(uint8_t queue_size, uint32_t ram_start){
	ble_cfg_t ble_cfg;
	memset(&ble_cfg, 0, sizeof(ble_cfg));
	ble_cfg.conn_cfg.conn_cfg_tag = APP_BLE_CONN_CFG_TAG;
	ble_cfg.conn_cfg.params.gattc_conn_cfg.write_cmd_tx_queue_size = 7;

	return sd_ble_cfg_set(BLE_CONN_CFG_GATTC, &ble_cfg, ram_start);
}

The BLE_GATTC_EVT_WRITE_CMD_TX_COMPLETE  event has a count field to indicate how many of the writes completed on that event.

[HuanVH]

I tried it, the result was a bit better, I scored 256 more bytes, and the infinite loop continued

    uint32_t err_code = NRF_ERROR_RESOURCES;
    ble_send_package_done = false;
    err_code = ble_ota_write_data(&p_sv_event->p_ota[write_data.device_handle], write_data.p_data, write_data.len);
    while(err_code == NRF_ERROR_RESOURCES)
    {
        err_code = ble_ota_write_data(&p_sv_event->p_ota[write_data.device_handle], write_data.p_data, write_data.len);
        nrf_delay_ms(100);
    }

uint32_t ble_ota_write_data(ble_ota_t *p_ota, uint8_t *data, uint16_t length)
{
    VERIFY_PARAM_NOT_NULL(p_ota);
    if(p_ota->conn_handle == BLE_CONN_HANDLE_INVALID)
    {
        return NRF_ERROR_INVALID_STATE;
    }
    ble_gattc_write_params_t const write_params =
    {
        .write_op = BLE_GATT_OP_WRITE_CMD,
        .flags    = BLE_GATT_EXEC_WRITE_FLAG_PREPARED_WRITE,
        .handle   = p_ota->peer_data_db.char_handle,
        .offset   = 0,
        .len      = length,
        .p_value  = data
    };
    return sd_ble_gattc_write(p_ota->conn_handle, &write_params);
}

[smackenzie]

Where is this being called from? 

If its inside an interrupt (like a uart write or something) then this process is probably taking too long. You can only stay in an interrupt for a small amount of time. 

If its on the main loop,try calling nrf_pwr_mgmt_run instead/before of nrf_delay_ms.

[HuanVH]

I am in fact experimenting with updating firmware for peripheral via central.
I get the firmware via uart, then burn it to flash.
I then sent this firmware by sending 16 bytes, until 4KB I wrote the data to flash on the peripheral.
I then sent a feedback back to the central, confirmed central and continued sending the remaining packets. All are done on the interrupt by BLE.
I had an error sending 4KB, after the central confirmed and continued sending the next 4KB, but I only sent about 128 bytes. I have set the check flag for the BLE_GATTC_EVT_WRITE_CMD_TX_COMPLETE event, but nothing happened.