Device: TMS320C28346
Device: TMS320C28346
Description of Issues:
I am encountering synchronization issues with the EPWM modules in a configuration where two separate synchronization chains are active.
1. EPWM7 Frequency Jitter (Interaction between Sync Groups)
Configuration:
I have configured two separate synchronization groups:
-
Group A: EPWM1 (Master) $\rightarrow$ EPWM2 $\rightarrow$ EPWM3
-
Group B: EPWM4 (Master) $\rightarrow$ EPWM5 $\rightarrow$ EPWM6 $\rightarrow$ EPWM7
Symptoms:
-
Frequency jitter occurs specifically on EPWM7.
-
The waveform appears stable at 100kHz, but jitter occurs at other frequencies.
-
Key Observation: If I disable the Master mode on EPWM1 (disable sync out), the jitter on EPWM7 disappears.
-
Code Workaround: In the attached code, enabling the logic under
//@@@@@@ if enable -> PWM7 ok.resolves the jitter.
Question:
Since EPWM1 and EPWM7 belong to different synchronization chains in my setup, I am unsure why EPWM1 is affecting EPWM7. Can this behavior be reproduced on the TI Evaluation Board (EVM), or does this indicate a specific noise/layout issue on our custom hardware?
2. EPWM7 Phase Shift Failure (in EPWM4-7 Chain)
Configuration:
-
EPWM4 to EPWM7 are synchronized (EPWM4 is Master).
Symptoms:
-
Phase control works for EPWM5 and EPWM6, but fails for EPWM7.
-
When changing the frequency/phase settings for the group (EPWM4–7), the phase shift is not updated for EPWM7.
-
Code Observation: Modifying the variables below the comment
@@@@@@ PWM7 phase shift is not appliedhas no effect.
Question:
I have not been able to find the root cause of why only EPWM7 fails to respond to phase shift changes while the rest of the chain operates correctly.
TEST CODE: 251203_28346 epwm test_June.Shin.zip
Your advice would be greatly appreciated.
Thank you.
