TMS320F28379D：Sampling data loss

I am using Simulink to drive the launchxl F28379d. When I set the baud rate to 115200, the sampled data has poor performance. Therefore, I increased the baud rate to 921600. When I did this, the sampled signal resolution was 0.0001s. However, in the first few seconds, the signal could not be sampled. The observed phenomenon is that the driver board had a signal first, and after a few seconds, it started sampling and monitoring.May I ask what caused this.

Answer 1

[Samar]

Hello @国栋,

The behaviour that is observed when the baud rate is raised to 921600—no data for a few seconds, then sampling resumes—is often caused by a combination of these factors:

1. Buffering Delay The serial port needs a moment to start sending data at high speed. During this time, no signal appears.
2. Wrong Clock Setting Your board uses a 10 MHz oscillator, but Simulink may default to 20 MHz. This mismatch causes SCI timing issues. ➤ Fix: In Hardware Settings → Clocking, set OSCCLK = 10 MHz.
3. Pin Setup SCI_A uses GPIO42 (TX) and GPIO43 (RX). If not correctly set in Simulink, data won't send. ➤ Fix: Set the right pins for SCI_A.
4. Computer-Side Serial Limits Your PC may delay starting serial communication, especially at very high baud rates.

Next Steps Recommendation

1. Correct the oscillator setting and GPIO configuration.
2. Apply a streaming buffer pattern (MathWorks Fast Serial Data Monitoring examples are very effective).
3. Rebuild and re-run with high baud. If the first few seconds are still blank but then streaming starts, the issue is resolved—this startup delay is expected behavior under this mode with high-speed streaming.

If the system never outputs data, it’s likely an OSCCLK or pin misconfiguration. Fixing those should restore full external-mode operation, even at 921,600 bps.

A similar issue has been discussed below in the MATLAB Answer. Refer it for more info:

www.mathworks.com/matlabcentral/answers/2000408-communicating-more-slowly-when-running-ti-launchpad-f28379d-in-simulink-external-mode?

Let me know once you've tried the above—I'd be happy to help validate any settings in your Simulink model or suggest next steps!