Cyclic Voltammetry - CV

[klebyn]

Hello
Good evening,
I would like to use your library (LMP91000) with Arduino (or Teensy).
Your library should be what I need.
I would like to do Cyclic Voltammetry - CV.
However I'm not sure exactly how to configure the library to scan for voltage (for example from 0 to 5V in subdivisions)
Would you have any tips or examples on which I can to base myself?

Thank you very much for your attention in advance.
Thank you

Cleber Borges

[vicatcu]

Hey, I don't know anything about Cyclic Voltammetry, but it sounds cool... maybe something useful to explore for Air Quality Egg? The library is a pretty transparent interface to the LMP91000 settings without any special provisions for "application logic." I mainly use it to set up the chip at startup and then don't talk to it again afterwards. Presumably, though, what you would do is call configure in a loop with different settings in your software and some delay between each iteration. You can see how configure is invoked in the example in the repository, and you can see the various constants that can be passed to configure as composite arguments in the header file.

[klebyn]

Hello
Thanks for answering!
Cyclic voltammetry basically consists of varying the electric voltage from X1 Volts to X2 Volts and then from X2 to X1 and repeating the process a few times.

There are some articles on Electrochemistry using the LMP91000.
Examples of articles in [1] and [2], but the authors do not provide the codes.

I understood the use of your library (or I think I did!).

My question is WHERE to configure the LMP91000 chip to accept the voltage variation.

Can I do this with the power pins?

I think the power supply should be 3.3V constant and make the voltage variation of the electrodes in a separate place. But I did not see where to do it. (Well, that's just a kick!)

Thanks
Cleber Borges

[1] - http://dx.doi.org/10.1016/j.bios.2014.06.053
[2] - http://dx.doi.org/10.1016/j.bios.2016.08.106

[vicatcu]

You would make a sequence of calls like this one from the example, but you would vary the parameters on each iteration.

That configure function takes three arguments. So if you wanted to do a loop with varying arguments, you'd have to figure out what those arguments should be ahead of time, and perhaps store them in arrays so that you could apply the appropriate set of arguments on each iteration of your loop.

To understand the settings you need to review the datasheet, and this diagram in the datasheet is pretty helpful. The various settings basically determine how each of blocks and "switches" are configured.

I haven't personally gone too deep in understanding the nuanced configuration of the chip, but you can set the bias (VWE - VRE) to (scaled VDD or scaled VREF) +/- 24%.