Waveform keeps moving up

[choliszt]

Hi all,

Was wondering if anyone could guide me in this. I am making a PPG and we finally managed to obtain transmission of signal from the circuit board. However, the graph still is very edgy (was the filter not good enough?). A worse problem is that the graph seems fine when it first appears from the right, but as it moves to the left the values keeps moving upwards along y axis. Moreover, I realize that the value returns to 0 at x = 0. Finally, I am not sure how we can get negative numbers for y axis values when Arduino is not supposed to get negative figures.

Best,

Edwin Neo

[James.M]

I can't open it since I don't have LV 2015 on my home computer, but a Sine wave coming through an analog input usually means you have a floating signal. Check your signals with a voltmeter while the program is running and see if the values match up.

If you save the Vi for Previous Version as 2014 or older, I can take a look at the code. This does sound like a wiring issue though.

[choliszt]

Hi, I haven't yet seen in myself but my team who designed the circuit has tested it on the oscilloscope and it works fine.

[altenbach]

Why are you opening a BT connection, but later use TCP read and TCP close??? Seems inconsistent. I would stick with the tools in the bluetooth palette!

Are you sure you are parsing the received data correctly? Can you show us a typical received string.

[vasileradueugen]

This is how it looks inside

[choliszt]

Hi all, attached is the photo of the results. As you can see, the waveform appears from the right and moves upwards when it approaches leftwards. Moreover, the values are negative and some of the edges are not yet filtered off.

Deadline's coming soon, if any help could be offerred it will be greatly appreciated.

[altenbach]

What is the visible vertical scale?

[choliszt]

With regards to the TCP connection, in my laptop (using LabVIEW Student and Educators' Edition 2015), whenever I take out the Bluetooth Read and Close Connection VI from the Bluetooth Protocol Palette, it changes to TCP...not too sure if it is a bug, only my Open Connection VI has Bt at the top right hand corner. It has been like this since I installed it. 

[choliszt]

It is amplitude sir. May I also ask if attaching the Decimal String to Number is the correct type of conversion to get the waveform we need for a more consistent waveform that doesn't have the upward motion as mentioned before? 

Just another question, what is the data type out from the data out terminal from Bluetooth Read VI? My Arduino coder told me he send out the data in floating point format.

[Dennis_Knutson]

Attaching a photo is wrong. You should know how to take a screenshot on the pc and attach that if you must attach images.

No, using the decimal to string is not correct if you have floating point numbers. Please read the Context Help.

You need to start troubleshooting closer to the source. Using a scope to read the source does not tell you if the arduino is connected correctly. Start with its ide to look at the adc values before they sent out with the bluetooth. In the LabVIEW program, create an indicator at the VISA Read and after you convert to floating point, before all of those Express functions.