bleprph_throughput demonstrates server side implementation required for NimBLE throughput example. It has characteristics supporting READ, WRITE and NOTIFY (THRPT_LONG_CHR_READ_WRITE, THRPT_CHR_READ_WRITE, THRPT_CHR_NOTIFY). The read characteristic holds 510 bytes (READ_THROUGHPUT_PAYLOAD) and the write characteristic accepts up to 509 bytes (WRITE_THROUGHPUT_PAYLOAD). Notifications are sent with a 509-byte payload (NOTIFY_THROUGHPUT_PAYLOAD). These sizes are chosen to maximize ATT PDU utilization with the default MTU of 512.

bleprph_throughput uses the nimble component as BLE host.

Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

idf.py -p PORT flash monitor

(To exit the serial monitor, type Ctrl-].)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

Example Output

I (573) BTDM_INIT: BT controller compile version [b73c48e]
I (573) system_api: Base MAC address is not set
I (573) system_api: read default base MAC address from EFUSE
I (663) phy: phy_version: 4500, 0cd6843, Sep 17 2020, 15:37:07, 0, 0
I (903) bleprph_throughput: BLE Host Task Started
I (933) bleprph_throughput: Device Address:
I (933) bleprph_throughput: 3c:71:bf:99:38:7a
GAP procedure initiated: advertise; disc_mode=2 adv_channel_map=0 own_addr_type=0 adv_filter_policy=0 adv_itvl_min=0 adv_itvl_max=0
I (1403) bleprph_throughput: connection established; status = 0
I (1433) bleprph_throughput: mtu update event; conn_handle = 0 mtu = 512

In a separate terminal flash and run corresponding blecent_throughput for full fledged throughput demo.

If at the blecent_throughput side notify is selected as GATT operation, then below console output can be observed:

I (23853) bleprph_throughput: subscribe event; cur_notify=1; value handle; val_handle = 14
GATT procedure initiated: notify; att_handle=14
GATT procedure initiated: notify; att_handle=14
GATT procedure initiated: notify; att_handle=14
GATT procedure initiated: notify; att_handle=14
.
.
.

*********************************
I (83943) bleprph_throughput: Notify throughput = 160466 bps, count = 2407

*********************************
I (83943) bleprph_throughput:  Notification test completed for stipulated time of 60 sec

Here, bps is bits per second; count is number of Notifications successfully sent.

Example Scope

This demo example along with blecent_throughput demonstrates stable GATT read/write and notify operations at high throughput. For notifications, the peripheral uses a pipelined approach: a counting semaphore (max 100) allows multiple notifications to be queued simultaneously (pipeline depth of 15). This enables the BLE controller to pack multiple PDUs into each connection event for maximum throughput.

Notifications are sent in os_mbufs packets. The example is configured with CONFIG_BT_NIMBLE_MSYS_1_BLOCK_COUNT=50 to provide sufficient buffer space. If mbuf exhaustion occurs during continuous transfer, the app yields briefly to allow the NimBLE host stack to free completed mbuf chains before retrying.