CCS/CC2650: CC2650 Sine signal sampling using ADC

Tarak MAAMMAR

Part Number: CC2650

Tool/software: Code Composer Studio

Hello,
I am trying to use the sensor controller in order to convert analog values by using the ADC. I just made a simple code in order to get values from an input analog pin and to convert them and this is the code :

//Initialization code

adcSelectGpioInput(AUXIO_A_INPUT_1);

fwScheduleTask(1);

//Execution Code

adcEnableAsync(ADC_REF_FIXED, ADC_TRIGGER_AUX_TIMER0);

S16 valeure;

adcStartAuxTimer0Trigger(50);

adcReadFifo(valeure);

state.echantillon = valeure;

adcDisable();

fwGenAlertInterrupt();

fwScheduleTask(1);

My problem is that when i try converting let say a sinusoidal signal i don't get nothing but a scramble of values even though i'm in very low frequencies (like 5-10 hz). I guess the problem is in the code or in the time needed execute a task in Sensor controller Studio. Any help would be welcome.

Thanks.

over 9 years ago

0 Eirik V over 9 years ago

TI__Guru 56590 points

Hello Tarak,
For fast sampling you can refer to the ADC Data Streamer example project in SCS. When using ADC_TRIGGER_AUX_TIMER0 the sensor controller must remain active and not enter sleep until you stop the aux timer trigger and disable the ADC.

0 Tarak MAAMMAR over 9 years ago in reply to Eirik V

Expert 1190 points

Hi Eirik Thank you for your answer it helped a lot.
But i still can't see which ADC mode is to be used for fast sampling of high frequency signals (synchronous or asynchronous) and which Trigger mode is best suited.
Thanks.

0 Eirik V over 9 years ago in reply to Tarak MAAMMAR

TI__Guru 56590 points

The "ADC Data Streamer" example project will give you the best starting point. Then simply alter the sampling interval here:
// Start ADC trigger timer at 20 kHz
adcStartAuxTimer0Trigger(50);

0 Tarak MAAMMAR over 9 years ago in reply to Eirik V

Expert 1190 points

Hi Eirik,
Thank you for your answer it was really it helped me a lot.
I am sampling signals wich frequencies might go up to 100 hz would you advise using a single variable to stock the sampled values or using a buffer to stock a groupe of successive values ?
And by the way, in the case that i'll be using a buffer would it then be possible to sample multiple signals at the same time ? (using a pin for each entry and a buffer for each entry)

0 Eirik V over 9 years ago in reply to Tarak MAAMMAR

TI__Guru 56590 points

Hello Tarak,
Use a buffer, either a plain array or use the Multi-Buffered Output Data Exchange resource.
Refer to the ADC help text (F1 -> ADC) and the Sampling Multiple Pins example code.

0 Tarak MAAMMAR over 9 years ago in reply to Eirik V

Expert 1190 points

Thank you Eirik this looks indeed like a possible solution.
Is there some links on examples using Multi Buffered Output Data exchange besides the SCS documentation ?

0 Eirik V over 9 years ago in reply to Tarak MAAMMAR

TI__Guru 56590 points

Yes, Capacitive Touch Data Logger.

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CCS/CC2650: CC2650 Sine signal sampling using ADC