How to confirm the no. of samples of signal in ADC result register

Hi Senthil,

You can simply use the combination of Array and Breakpoint. Initialize an array of 250 elements and keep incrementing the same with ADC samples. Insert a break-point at the 20ms point. Check the array values for the number of elements entered. Is it possible?
Another simple way is to burst the samples through SCI instead of using printf.

Regards,
Gautam

Hi Senthil,

Note that there is an erratum for this device when operating the ADC at <1MHz ADCCLK:

It is recommended to configure the ADCCLK at a more nominal frequency, and then use the ePWM (or other trigger source) to control the sample rate. 

Thanks Gautam. I got samples using 'breakpoint' with option of write data in file. However, the no. of samples doesn't match the calculated value. Could u please tell that step by step procedure to verify the ADC working.

How may elements in the array got filled? You need to first analyze what you implement to what you observe.

I have tried with sampling more than 1MHz. However, the i am not getting proper sampling data. Could you tell me the step by step procedure for testing the ADC function and output results.

Hi Senthil,

Are you sourcing a signal with bandwidth > 1MHz into the ADC input, or are you trying to sample at > 1MSPS?

I think the procedure would be to start with a DC input to the ADC. Once you have that working, you can increase the sample rate. Once you have it working with increased sample rate, then try a sine or other periodic input from a function generator or other signal source.

The source signal is much less than 1MHz and the sampling rate is greater than 2 MHz. However, It is found that the digital value corresponding to max value is fixed 3000 and digital value is varying with respect to minimum amplitude. Example: case1: Applied source voltage varies between 0-3V. The corresponding ADC sample values obtained between 500-3000 (digital value). case2: Applied source voltage varies between 0-2V. The corresponding ADC sample values obtained between 1500-3000 (digital value). Actual digital sample value should be between 500-2000 and 500-3000 for 0-2V and 0-3V, respectively. Kindly help me to solve this problem.

Hi Senthil,

What does the signal conditioning circuitry look like? What is the impedance of your ADC signal source?

The Op amp signal conditioning circuit is used to as buffer. Kindly give me your email id to send the attachment file.

Hi Senthil,

You can send the circuit to c2kforum@list.ti.com (provide a link to this post)

I had sent mail to c2kforum@list.ti.com and got reply as "The mail was not sent to the list subscribers because you do not have
permission to send messages to this mailing list."

Hi Senthil,

I'll look into why the message is bouncing. In the meantime, you can use dcottier AT ti DOT com.