Throughput of Nrf52832 with MTU 247

RE: Throughput of Nrf52832 with MTU 247

Vidar Berg — Fri, 28 Feb 2020 08:37:21 GMT

Hi,

[quote user="Yangbo"]280 kbps mean 280 * 1000 / 8 / 1.024 = 34.18 KB/s?[/quote]

Yes, correct. Result of the same example with another nRF device on the other side of the link:

[quote user="Yangbo"]MTU 247,valid user data 244, I expect 4~6 packets per connection interval, means speed can be more than 47KB/s. Is anything wrong with my understanding?[/quote]

No, your understanding is correct. The only problem is that the iPhone may choose to receive fewer packets. Here is a thread gives an example of how iPhones may limit the bandwidth: https://devzone.nordicsemi.com/f/nordic-q-a/40597/maximizing-nrf52-ios-ble-throughput-in-both-directions

RE: Throughput of Nrf52832 with MTU 247

Linxi — Thu, 27 Feb 2020 13:33:58 GMT

Hi, thank you very much.

280 kbps mean 280 * 1000 / 8 / 1.024 = 34.18 KB/s?

My experiment speed is 23KB/s. Sorry for my error writing 23kb/s.

MTU 247,valid user data 244, I expect 4~6 packets per connection interval, means speed can be more than 47KB/s. Is anything wrong with my understanding?

My connection interval is 20ms and throughput is 23KB/s. It seems like only 2 packets sent per connection interval. 1000/20 * 2 * 244bytes / 1024 = 23.8KB/s. Do you have any ideas to improve the bandwidth to let me send more packets per connection interval ?

RE: Throughput of Nrf52832 with MTU 247

Vidar Berg — Thu, 27 Feb 2020 12:48:48 GMT

Hi,

Attached below is a modified version of the ble_app_uart example found in SDK 13.1.0. It's very simple. It sends data as fast as it can to the client when notifications get enabled and use a timer to determine the transfer rate while doing so. Please try and test it on your side and see if it gives you any better results.

UART log when I tested it with an iPhone 8:

Modified ble_app_uart example. It still uses s132, but that shouldn't make a difference.

devzone.nordicsemi.com/.../ble_5F00_app_5F00_uart_5F00_throughput.zip

RE: Throughput of Nrf52832 with MTU 247

Linxi — Thu, 27 Feb 2020 08:40:34 GMT

Hi Vidar:

Thanks for your comments. My softdevice veriosn is S332 4.0.2. Perhaps the key is connection bandwidth. In SDK 13.10 document, I find no API to set this. Can you help?

RE: Throughput of Nrf52832 with MTU 247

Vidar Berg — Thu, 27 Feb 2020 08:31:39 GMT

Hi,

23 Kb/s sounds a bit low. I can try to repeat the test here with the ble_app_uart sample. What SDK version is this based on? As you may have seen already, the Softdevice specification includes max. throughput numbers of when you have a nRF5 device on both sides of the link: Bluetooth Low Energy data throughput