UART BLE Example - Data size limit

RE: UART BLE Example - Data size limit

Simon — Wed, 05 Jun 2019 16:29:23 GMT

Do you want to send 64 bytes in a single packet or divided over several packets? I assume the first.

BLE 4.2 and 5.0 supports the feature Data Length Extension (DLE), which makes it possible to send up to 244 bytes in one packet (see image below).

In order to set the data length, use the function sd_ble_gap_data_length_update(). If you look at the ble_app_uart_mtu_throughput example, you can see that this function is called in the following manner:

button_evt_handler()-->data_len_set()-->nrf_ble_gatt_data_length_set()-->data_length_update()-->sd_ble_gap_data_length_update()

Remember to set the MTU size accordingly (NRF_SDH_BLE_GATT_MAX_MTU_SIZE).

Best regards,

Simon

RE: UART BLE Example - Data size limit

firmware_master — Mon, 03 Jun 2019 17:00:25 GMT

I have checked the USART-BLE example as given and it looks like I should be able to send much larger messages. What is the need for the new example?

Thanks

RE: UART BLE Example - Data size limit

Simon — Mon, 03 Jun 2019 13:58:57 GMT

Check out the ATT_MTU Throughput Example of how to send more than 32 bytes (By increasing the ATT_MTU size).

Best regards,

Simon