Testing througput exemple. Not reaching maximum data rate.

[Eduardo Carletti]

Hello! 

I am working on a project where a large file (approx. 192MB) has to be transferrede from the nRF52832 to a mobile phone. Due this file size, transmission is taking too long (more than 5h) using BLE default configurations. So I decided to give a try on the high speed modes.

Testing whith the throughput example on sdk16 did in fact achieved higher rates. But not even close to what has been reached here and here. I have, in the best case, 400kbps.

My testing scenario is a nRF52832 dev kit, wich is the tester, and a nRF52840 dongle, wich is the responder. Both boards are using softdevice S132 V6.1.1. 

Does anyone have a guess on what am I doing wrong?

[Eduardo Carletti]

So, after a bunch of trying, found that I needed to change the data length. Gone to 251B, now I have 1300kbps. That's great.

My next step is to test this whith an smartphone. Any ideas? I really don't know where to start..

[Simonr]

Hi Eduardo

I'm glad you were able to figure out what was missing on your own. To get started with testing on a phone, I suggest looking at the nRFConnect or nRFToolbox app for Android or iOS. The apps also have their source code publicly available on GitHub.

Best regards,

Simon

[Eduardo Carletti]

Hi Simon, I was looking for something more straightforward. This exemple made by Torbjorn helped me. As I don't have the camera board, I had to modify the firmware to send an array of bytes (binary data extracted from a JPEG picture). In fact, I'd like to suggest to Nordic to provide this source code together with the SDK. Only down side is that I wasn't able to test using iPhone, and am not sure if this kind of data rate would be feasible.

[Simonr]

Hi Eduardo

I see where you're coming from, but we've made a conscious choice to not have these very specific demos as part of our example projects in the SDK, as additional peripheral HW is required to run the ble_image_transfer demo, and the ble_app_att_mtu_throughput does demonstrate similar throughput by transmitting the logger output to another device, I.E. a phone using the nRFConnect app.

I'm sorry about the initial misunderstanding, as I thought you wanted to develop a phone app to test throughput on. In order to test throughput when communicating with an iOS device I would suggest either editing the ble_app_att_mtu_throughput example to be able to communicate with a phone and read the throughput there. You can alternatively use one of the other examples to transfer X amount of data and see by the timestamps in the log how long it takes to transfer a set amount of data, which would make it pretty straight-forward to calculate the throughput between the devices.

Best regards,

Simon