TMS320F28388D: Contents in DBCTL register will be cleared after setting SHDWDBCTLMODE

Part Number: TMS320F28388D

Hi expert,

My customer would like to shadow load DBCTL settings. They find contents in DBCTL will be cleared when configuring SHDWDBCTLMODE in below sequence. I can also reproduce it easily wtih example project epwm_ex4_deadband by adding only two lines of code.

Below two lines are what I am adding:

EPwm1Regs.DBCTL2.bit.SHDWDBCTLMODE = 1;
EPwm1Regs.GLDCFG.bit.DBCTL = 1;

Step one screen shoot, you can see DBCTL is correctly configured here.

Step two, after step into line 417, contents in DBCTL is cleared.

I didn't see explicit requirements on sequence of configuring these two registers. So could you help me confirm on why this happens?

Thanks

Sheldon