Hi C2000 Concerto Tripzone oneshot problem

Hi, Im currently implementing the ILPFC F28035 example code to the concerto F28M35 develpment kit

I build the incremental build 1 from the kit IL_PFC 

the code 

EALLOW;

EPwm1Regs.TZSEL.bit.OSHT1 = 1;
EPwm1Regs.TZCTL.bit.TZA = TZ_FORCE_LO; // EPWM1A will go low
EPwm1Regs.TZCTL.bit.TZB = TZ_FORCE_LO; // EPWM1B will go low

EDIS;

I find out that the PWM 1would alive

but I implement the same code to the concerto F28M35 platform

(using fixed point, and the M3 side is pinout to control side by device example setup_m3 project))

the PWM is force Low 

I check the datasheet from F28M35  it state  "once the TZSEL.bit.OSHT1 is set , the TZFLAG is set. and need to be clear after initialization for future trip function.

but I add the code right after the code like this 

EALLOW;

EPwm1Regs.TZSEL.bit.OSHT1 = 1;
EPwm1Regs.TZCTL.bit.TZA = TZ_FORCE_LO; // EPWM1A will go low 
EPwm1Regs.TZCTL.bit.TZB = TZ_FORCE_LO; // EPWM1B will go low

EPwm1Regs.TZCLR.bit.OST = 1; // Clear any spurious OC trip

EDIS;

But I still can't clear the TZFLAG to 0 thus the PWM is not alive...

I have no idea how to clear that flag to make the PWM function normally and provide the trip function.

But I do this 

EALLOW;

//EPwm1Regs.TZSEL.bit.OSHT1 = 1;
EPwm1Regs.TZCTL.bit.TZA = TZ_FORCE_LO; // EPWM1A will go low 
EPwm1Regs.TZCTL.bit.TZB = TZ_FORCE_LO; // EPWM1B will go low

EDIS;

all of the sudden the PWM comes to alive and the trip function is work properly

( I check the function by set the VBUS_OVP_THRSHLD to a number that cause the TZFRC.bit.OST turn off the PWM)

interrupt void SECONDARY_ISR(void)
{
EINT;

if (VbusAvg > VBUS_OVP_THRSHLD)//Check for Vbus OV Condition; Use for Build 2 & 3
//if (Vbus > VBUS_OVP_THRSHLD)//Use this for Build 1 test
{
OV_flag = 1;
EALLOW;
//EPwm4Regs.TZFRC.bit.OST = 1;//Turn off PWM for OV condition
EPwm1Regs.TZFRC.bit.OST = 1;//Turn off PWM for OV condition
EDIS;

VbusTargetSlewed = 0;
VbusTarget = 0;
pfc_on_flag = 0;
//Gui_Vbus_set = 0;
}

is that okay if I comment out the "EPwm1Regs.TZSEL.bit.OSHT1 = 1;"

or is there better way to do?

thanks in advanced. 

Tom Chen