RE: How to reach maximum BLE throughput at 2M PHY with nRF5340DK (peripheral) and nRF52 Dongle (central)?

Jakob Ruhe — Wed, 21 May 2025 09:24:33 GMT

Hello,

You should indeed be able to reach higher throughput over 2 Mbit Bluetooth. Have a look at the Throughput sample application: Bluetooth: Throughput for inspiration.

When I used it with 2 Mbit some time ago I got the following results between two nRF52840-DK close to each other:

==== Starting throughput test ====
PHY update pending
LE PHY updated: TX PHY LE 2M, RX PHY LE 2M
Connection parameters update pending
Connection parameters updated.
 interval: 320, latency: 0, timeout: 1000
LE Data length update pending
LE data len updated: TX (len: 251 time: 2120) RX (len: 251 time: 2120)
The test is in progress and will require around 20 seconds to complete.
                                                                           
Done
[local] sent 3434805 bytes (3354 KB) in 20001 ms at 1373 kbps
[peer] received 3434805 bytes (3354 KB) in 6939 GATT writes at 1391672 bps

1373 kbps is indeed higher than 54 kbps. Note that I used a higher Connection Interval than you. Have a look at Increasing BLE Throughput - Nordic Q&A - Nordic DevZone - Nordic DevZone to which role the Connection Interval plays.

To verify that you are using 2 Mbit you can use the function `bt_conn_get_info()`. Or you can use a Bluetooth sniffer.

I know nothing about Blatann and I have never tried running the Host on the PC. Are they communicating over serial? At which speed? I think such a setup also can introduce latencies. If you are using an UART at 115 kbps that will introduce a bottleneck for the Bluetooth communication link.