RE: Usage of Queued Read and Write

Susheel Nuguru — Thu, 06 Jan 2022 14:09:37 GMT

Hi Hani,

If the read is longer than the max MTU size then you need to use the offset field and keep track of how much data you already read.The code you used is good for the first read but you need to extend this some thing like below in the event handler. Please note that i just wrote the code and have not compiled it, so use this as a logic and not as a solution in itself

static uint32_t remaining_read_count = 500;

static void current_time_read(ble_hrs_c_t * p_ble_hrs_c, ble_evt_t const * p_ble_evt)
{
    ble_cts_c_evt_t evt;
    uint32_t        err_code = NRF_SUCCESS;

    // Check whether the event is on the same connection as this HRS instance
    if (p_ble_hrs_c->conn_handle != p_ble_evt->evt.gattc_evt.conn_handle)
    {
        return;
    }
	else
	{
		uint8_t len = p_ble_evt->evt.gattc_evt.params.read_rsp.len;
		memcpy(&YOUR_DATA_STORAAGE[500-remaining_read_count], p_ble_evt->evt.gattc_evt.params.read_rsp.data, len);
		remaining_read_count = remaining_read_count - len;
		if(remaining_read_count)
		{
			// initiate another read with offset set to len
			    nrf_ble_gq_req_t hrs_c_req;

				VERIFY_PARAM_NOT_NULL(p_ble_hrs_c);

				memset(&hrs_c_req, 0, sizeof(hrs_c_req));
				hrs_c_req.type                     = NRF_BLE_GQ_REQ_GATTC_READ;
				hrs_c_req.error_handler.cb         = gatt_error_handler;
				hrs_c_req.error_handler.p_ctx      = p_ble_hrs_c;
				hrs_c_req.params.gattc_read.handle = p_ble_hrs_c->peer_hrs_db.hrm_handle;
				hrs_c_req.params.gattc_read.offset = len;  

				err_code = nrf_ble_gq_item_add(p_ble_hrs_c->p_gatt_queue, &hrs_c_req, p_ble_hrs_c->conn_handle);
				// Handle errors if any
		}
	}
}

void ble_hrs_c_on_ble_evt(ble_evt_t const * p_ble_evt, void * p_context)
{
    ble_hrs_c_t * p_ble_hrs_c = (ble_hrs_c_t *)p_context;
    NRF_LOG_DEBUG("BLE event handler called with event 0x%x", p_ble_evt->header.evt_id);

    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GATTC_EVT_READ_RSP:
            handle_read(p_ble_hrs_c, p_ble_evt);
            break;

        case BLE_GATTC_EVT_HVX:
            on_hvx(p_ble_hrs_c, p_ble_evt);
            break;

        case BLE_GAP_EVT_DISCONNECTED:
            on_disconnected(p_ble_hrs_c, p_ble_evt);
            break;

        default:
            break;
    }
	
}