F28335 eZdsp ADC Conversion Result

sugita

Intellectual 270 points

Hello,

I have been evaluated F28335 eZdsp. I have problem about ADC.

I use external reference (JP1 is shorted, 2.048V) on ADCREFIN.

The conversion result is as follows.

Input Result

0.5V 0.50V

1.0V 0.95V

1.5V 1.40V

2.0V 1.88V

2.5V 2.33V

If the input is 2.5V, 2.47V is obtained approximately, I think.

If I have created a user board, I can get 2.47V?

I hope someone tell me your experience or information.

Best regards,

Nathan Morgan

over 14 years ago

0 Manoj Santha Mohan over 14 years ago

TI__Guru 55700 points

Nathan,

I'm not quite clear what your exact question is. It is difficult to tell whether all the ADC conversion for 2.5v will consistently result in 2.47v. But, if the custom board is designed correctly and ADC's are configured correctly we expect the ADC results to meet the specs defined in Pg: 168 section 6.15 named "On-Chip Analog-to-Digital Converter" of TMS320F28335/F28334/F28332/F28235/F28234/F28232 Digital Signal Controllers (Rev. I)

Hope this helps.

Regards,

Manoj

0 sugita over 14 years ago in reply to Manoj Santha Mohan

Intellectual 270 points

Manoj,

Thank you for your reply. I read page 28, 1.8 ADC Calibration of spru812a.pdf again.

And I found "If the system is reset or the ADC module is reset using Bit 14 (RESET) from the ADC Control Register 1, the routine must be repeated."

Yes, I did reset ADC in my code. Your reply made me read again. Thank you!

Best regards,

Nathan

C2000™︎ microcontrollers

C2000 microcontrollers forum

F28335 eZdsp ADC Conversion Result