Real-time data streaming for PID tuning

[ychen25]

Hello,

I'm using nRF54L15DK and nRF Connect SDK 2.9.0. I'm developing a project for PID control of the temperature of a peripheral, let's say a heater. The feedback is measured through ADC. Now I'm trying to tune the PID parameters, is there a good way for visualization of my real-time temperature readings? I'm also sending the temperature via BLE to my mobile phone. It would be great to visualize the data readings directly in the mobile phone application. Do you have any recommendations? Thank you.

[Sigurd Hellesvik]

Hi,

I recommend that you have a look at the nRF-Toolbox. This has open source code, and has an HRS monitor that graphs things like you maybe want.

Unofficial sample:
In my spare time I did something like just that receently. See this.
Disclaimer: Im not an Android developer, so take it with a huge pinch of salt. But hey maybe my commit history can be of some inspiration.
For the matching nRF Source code, I must admit that I forgot to push that to git, and then my PC crashed.

Regards,
Sigurd Hellesvik

[ychen25]

Hi Sigurd, 

Thank you very much for the recommendation and your sharing. I will take a look and come back if I have questions. Thanks

[Sigurd Hellesvik]

Hah, I had the project for the nrf it in git after all!

Unofficial sample to go with the app I linked previously

https://gitlab.com/hellesvik/small_things_ncs/-/tree/main/temp_regulator

[ychen25]

Hi Sigurd,

Thanks for the update. I tried the nrf-toolbox app but I didn't find a curve drawing function in IOS app. Also, as I don't have an Android device, I don't think I will be able to try your app?

It's OK that the data streaming is not real-time. Now I want to find a simple solution to save my ADC reading data and export it as a csv. Can I achieve it with nRF Connect IOS app? Thank you.

[Sigurd Hellesvik]

ychen25 said:

Thanks for the update. I tried the nrf-toolbox app but I didn't find a curve drawing function in IOS app. Also, as I don't have an Android device, I don't think I will be able to try your app?

Yea, my app is only for Android.

Try to open the iOS nRF Toolbox on App Store and see if any of the apps there look similar to what you need. That is what I do to find a starting point.

ychen25 said:

It's OK that the data streaming is not real-time. Now I want to find a simple solution to save my ADC reading data and export it as a csv. Can I achieve it with nRF Connect IOS app?

It depends on if you want to store all data on the device, and then send in bulk.
Or if you want to send data live, and then save it on the device.
Which of the above?

[ychen25]

Sigurd Hellesvik said:

It depends on if you want to store all data on the device, and then send in bulk.
Or if you want to send data live, and then save it on the device.
Which of the above?

Hi Sigurd,

I've figured out how to do option (1) store all data on the device, and then send in bulk; 

I can share the log and export as csv in my IOS nRF Connect app;

Could you let me know how to achieve option (2) send data live, and then save it on the device? Thank you.

[Sigurd Hellesvik]

ychen25 said:

Could you let me know how to achieve option (2) send data live, and then save it on the device?

You make a BLE service that notifies when the data is updated.
Then the handler on the iOS will add this data to a list locally on the iOS.
Then you use iOS app functions to export your list to CSV.

This is kinda vague, as I do not know how iOS developement works: My speciality is the nRF.

Is this enough for you?

[ychen25]

Yes that's what I'm doing now. It's good enough for me now. Thank you!

[Sigurd Hellesvik]

Oh, I realize the misunderstaning, as I used "device" for both Phone and nRF.

Let me rephrase to be more clear:

1. Stream data from nRF to Phone and store on Phone

See my previous message

2. Store data on nRF and send to Phone in bulk

The SMP Protocol lets you send file system data to the Phone over BLE. See the SMP Server sample and its "Download file from File System" feature.