RX and TX characteristics in ble_app_uart example

RE: RX and TX characteristics in ble_app_uart example

BarbaraTurner — Thu, 02 May 2019 07:06:49 GMT

That's wrong answer! The peripheral device uses TX Characteristics to send notifications and RX_Characterisctics to received data from central.

// Add the RX Characteristic.
memset(&add_char_params, 0, sizeof(add_char_params));
add_char_params.uuid = BLE_UUID_NUS_RX_CHARACTERISTIC;
add_char_params.uuid_type = p_nus->uuid_type;
add_char_params.max_len = BLE_NUS_MAX_RX_CHAR_LEN;
add_char_params.init_len = sizeof(uint8_t);
add_char_params.is_var_len = true;
add_char_params.char_props.write = 1;
add_char_params.char_props.write_wo_resp = 1;

// Add the TX Characteristic.
/**@snippet [Adding proprietary characteristic to the SoftDevice] */
memset(&add_char_params, 0, sizeof(add_char_params));
add_char_params.uuid = BLE_UUID_HAM_AUDIO_PACKET_CHARACTERISTIC;
add_char_params.uuid_type = p_nus->uuid_type;
add_char_params.max_len = BLE_NUS_MAX_TX_CHAR_LEN;
add_char_params.init_len = sizeof(uint8_t);
add_char_params.is_var_len = true;
add_char_params.char_props.notify = 1;

add_char_params.read_access = SEC_OPEN;
add_char_params.write_access = SEC_OPEN;
add_char_params.cccd_write_access = SEC_OPEN;

I have modify this example for my own use, removing TX characteristics as I need one way link, from central to peripheral. It works.

RE: RX and TX characteristics in ble_app_uart example

Jeffrey Haynes — Mon, 13 Jun 2016 01:20:49 GMT

Are you sure the documentation is incorrect? That was my first thought but I believe the characteristics are written from the standpoint of the application, not the device (peer).

RE: RX and TX characteristics in ble_app_uart example

diode — Thu, 12 Nov 2015 18:47:05 GMT

This makes more sense. Thanks.

RE: RX and TX characteristics in ble_app_uart example

diode — Thu, 12 Nov 2015 18:44:34 GMT

I misunderstood the concept of notification. The data written to this notification-enabled characteristic will be pushed to the client. Thanks for the clarification.

RE: RX and TX characteristics in ble_app_uart example

Petter Myhre — Thu, 12 Nov 2015 09:58:36 GMT

The notifications are sent by using the RX characteristic. What do you mean by "when the data are already in the notification packet"?

RE: RX and TX characteristics in ble_app_uart example

Petter Myhre — Thu, 12 Nov 2015 09:55:32 GMT

The documentation is incorrect, it should be:

TX Characteristic (UUID: 6E400002-B5A3-F393-E0A9-E50E24DCCA9E) The peer can send data to the device by writing to the TX Characteristic of the service. ATT Write Request or ATT Write Command can be used. The received data is sent on the UART interface.

RX Characteristic (UUID: 6E400003-B5A3-F393-E0A9-E50E24DCCA9E) If the peer has enabled notifications for the RX Characteristic, the application can send data to the peer as notifications. The application will transmit all data received over UART as notifications.

I have reported this.