MSP432 ADC sample rate with Energia

Barry,
You may also want to try the Energia forum. I am not familiar with the Energia, but I have been told that you can use the SimpleLink drivers with Energia. This may be another option.

dev.ti.com/.../

Chris

PS. In the tags you point to a number of MSP430 devices but no MSP432. Is your question about msp430 or msp432?

It is msp432 . I'll try that , thanks a lot

Barry,

When it says the maximum analogRead() speed, this isn't really a sample rate, but just a measure of how fast Energia can do one ADC read. Each time you call analogRead(), Energia will do one read of the specified port. You then need to move that value into memory or act on it in some way (like sending it over UART or SPI) which will add additional latency. To slow down the sample speed, you could try adding delay() functions before the next read.

-Daniel

Daniel,

Thanks a lot! Because I'm recording a sound data here , so what should I do if I want a higher sample rate?

If you need a higher sample rate than that, you will need to use non-Energia code. Energia maxes out at 10KHz.

This thread shows how to combine Energia code with C code to configure the ADC to get higher sample rates (although it is for a different device, the principle of combing Energia and non-Energia C code together still applies.) 

Go directly to the hardware - I don't know if driverlib() works in Energia, but you can certainly set the registers yourself.

Daniel,

If I use a external ADC instead of the internal one, can I get higher sample rate with analogread()?
Thanks

No, because AnalogRead() only works with the internal ADC. You would need to use SPI or whatever protocol the ADC uses.

Energia is specifically designed to make things simple. Once you get outside of "simple" you need to look at other options. Sampling at 30 kHz rates or so is no longer simple.

I suggest you look at CCS and driverlib() it gives you total control over the hardware without the overhead of Energia. It has examples that will get you most of the way to where you want to go.

You also have to figure out what you are going to do with all the data. You only have 64K of RAM which can only hold 2 seconds of audio at 30 kHz sampling. (And nothing else!)

Keith,

Thanks a lot for the help, I will use a sd card to store the data. I know things isn't that simple with energia if I want higher sample rate but it seems like my only options for now , if I choose to use ccs where can I find useful samples? I'm new here...

Appreciated

thanks, I'll look into it!