Why does TI 28379D DAC Block gradually increases amplitude by time.

I have been using TI F28379D MCU to generate sine wave from DAC Block on Simulink.

I see that at the beginning the block outputs proper sine wave like below.

By time, the amplitude of the wave keeps increasing as seen in below images.

After 20 minutes:

After 1 hour:

Answer 1

[Vishwa]

Hi Srija,

I failed to reproduce your issue on my end. Could you please reply if the problem still persists and in which version of MATLAB you are facing this issue?

I am able to successfully generate consistent sin wave from DAC-B library block in Simulink on MATLAB R2023b.

(After 1 hour)

It could be happening because of faulty TI MCU or your digital oscilloscope.

Here are few steps you can take to debug this issue:

1. Try replacing the probes. Try to see if the problem persists even on other oscilloscopes.
2. Try checking if you are getting proper ground voltage (0V). Then see if you are getting 5 Volts and 3.3 Volts with respect to ground on F28379D.
3. Is Simulink able to deploy the generated code to your MCU. Check if the Debug Probe XDS100 is not being used by other softwares, such as CCS.
4. In the Simulink model, check if the Bias block is correctly set. Check if you are using correct DAC block.

These steps will surely help you get more clarity on what is causing this issue.

You can also view the output in Simulink itself, thereby removing oscilloscope from the loop. In Simulink, configure a GPIO Pin as input pin by using a Digital Input library block. Then on MCU board you can short DABOUTB pin and configured GPIO input Pin. Now with “Monitor and Tune” feature on Simulink, you should be able to view the DAC B output.

For Information on how to view the output in Simulink you can refer: Signal Monitoring and Parameter Tuning over XCP on Serial - MATLAB & Simulink - MathWorks India

Good Luck!

Regards,

Vishwa