CCS/CC2650: ADC Buffer Example

Chan Man Chan

Part Number: CC2650

Tool/software: Code Composer Studio

Hello, I have problems related to the ADC Buffer Example provided by TI. I have my CC2650 LaunchPad and I am using CCS to run the ADC Buffer Example.

I use Putty to see the ADC output.

Even if I do not connect any pins physically, Putty still shows some results as below:

I wonder how these values come because I do not connect any pins.

Besides, where can I change in the program in order to read analogue signals at certain pins? I know that DIO23-30 pins are used for ADC but I don't know how to modify the program to read the analogue signals at certain pins.

Any replies will be appreciated. Thanks in advance!

over 6 years ago

0 YiKai Chen over 6 years ago

Guru 735695 points

Since ADC pins on LAUNCHXL-CC2650 are left float, it's normal to see those value. If you look into source code of ADC buffer example, it calls "ADCBuf_open(Board_ADCBuf0, &adcBufParams);" to use Board_ADCBuf0 which is DIO_23. So, you can apply 0V to 3V to DIO_23 to test it.

0 YiKai Chen over 6 years ago

Guru 735695 points

I find there is something wrong on adcbufcontinuous example in TI RTOS for CC2650 2.21.00.06 on LAUNCHXL-CC2650 and raise another post to ask TI to verify it.

0 Chan Man Chan over 6 years ago in reply to YiKai Chen

Prodigy 170 points

Thanks for your quick reply, actually, I tried the same as you.

I tried to connect GND to DIO23 (although I do not know which pin the program is referring to, I just test randomly),

I do not see any value in Putty that is close to 0.

Anyway, thank you for raising another post and I am going to move to there for replies from TI.

Thank you so much!!

0 TER over 6 years ago

TI__Guru**** 317180 points

If you trace the definitions:

continuousConversion.adcChannel = Board_ADCBufChannel0;

#define Board_ADCBufChannel0 (0)

This points to the first element in

const ADCBufCC26XX_AdcChannelLutEntry ADCBufCC26XX_adcChannelLut[] = {
    {PIN_UNASSIGNED, ADC_COMPB_IN_VDDS},
    {PIN_UNASSIGNED, ADC_COMPB_IN_DCOUPL},
    {PIN_UNASSIGNED, ADC_COMPB_IN_VSS},
    {Board_DIO23_ANALOG, ADC_COMPB_IN_AUXIO7},
    {Board_DIO24_ANALOG, ADC_COMPB_IN_AUXIO6},
    {Board_DIO25_ANALOG, ADC_COMPB_IN_AUXIO5},
    {Board_DIO26_ANALOG, ADC_COMPB_IN_AUXIO4},
    {Board_DIO27_ANALOG, ADC_COMPB_IN_AUXIO3},
    {Board_DIO28_ANALOG, ADC_COMPB_IN_AUXIO2},
    {Board_DIO29_ANALOG, ADC_COMPB_IN_AUXIO1},
    {Board_DIO30_ANALOG, ADC_COMPB_IN_AUXIO0},
};

If you want to use DIO30, you can define something like this:

continuousConversion.adcChannel = Board_ADCBufChannel10;

#define Board_ADCBufChannel10 (10)

which will use the last element in the table.

Also see

e2e.ti.com/.../549849

0 Chan Man Chan over 6 years ago in reply to TER

Prodigy 170 points

Thanks for your reply and I will try later!

I also want to know would it be possible to display the value in the console rather than in Putty?

Thanks again in advance.

0 YiKai Chen over 6 years ago in reply to Chan Man Chan

Guru 735695 points

I change "#define Board_ADCBufChannel0 (0)" to "#define Board_ADCBufChannel0 (3)" to allow DIO_23 as ADC input and it works.

0 Chan Man Chan over 6 years ago in reply to YiKai Chen

Prodigy 170 points

My board is also working now, thank you for all of the replies!

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CCS/CC2650: ADC Buffer Example