TMS320F280039C: ADC External Reference issue

Hi Edu,

Are you running any of C2000ware examples?

Thanks,

Susmitha

Hi Susmitha,

As mentioned before I found this thread regarding this same topic:

https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/1239050/tms320f280039c-adc-reference-issue

In this thread "adc_ex1_soc_software", from C200 Ware, is used as an example to modify and use External Reference adding the function ADC_setVREF(...). I followed what that thread mentioned and tested on the same "adc_ex1_soc_software" adding:

ADC_setVREF(ADCA_BASE, ADC_REFERENCE_EXTERNAL, ADC_REFERENCE_3_3V); 

I had no successful result using that modified example either. Whenever I changed, using the debugger, ANAREFCTL to 0 i got correct measurements and when setting ANAREFCTL = 1 I got incorrect measurements (4096).

Regards,

Edu.

Hi Edu,

You can either configure the ADC reference voltage using registers or Sysconfig. We usually recommend using Sysconfig , which is GUI based and easy to implement.

This is how it looks.

Can you try above and let me know? Do not change any registers or add any code manually .

Thanks,
Susmitha

Hi Susmitha,

To keep it simple, I used "adc_ex1_soc_software" example and changed to External Reference through Sysconfig, as you suggested.

I had no successful result. When Analog Reference set to Internal the readings are correct, when changing to External I get incorrect measurements (4096).

*These Interal/External Reference changes have been done with Sysconfig, as you requested.

Regards,

Eduardo.

Hi Eduardo,

Had you ring pin 45 actually goes to the ADC reference input on MCU package? Perhaps there is a typo on the silk or booster header pin map card. It happens sometimes pins even entire headers get marked incorrectly last-minute changes in documentation or PCB layouts.

Regards,