CCS/CSD95490Q5MC: Control CSD95490Q5MC by using TMS320F28379s

Tool/software: Code Composer Studio

I want to using TMS320F28379s to control CSD95490Q5MC. 

But, I find that the EN/FCCM pin on CSD95490Q5MC has a internal pull-down resistor.

I configured the PGPIO13 pin, which is direct connected to EN/FCCM(pin 11),  as input or open-drain output, but it can't ENABLE diode emulation mode(DEM) for sync FET.

And the measured level on EN/FCCM(pin 11) is low.

code: 

1. Configure the PGPIO13 pin as input

EALLOW;
    GpioCtrlRegs.GPADIR.bit.GPIO13 = 0;         //
    GpioCtrlRegs.GPAPUD.bit.GPIO13 = 1;    // Disable pull-up on GPIO13
EDIS;

2. Configure the PGPIO13 pin as open-drain output

EALLOW;
    GpioCtrlRegs.GPADIR.bit.GPIO13 = 1;         //
    GpioCtrlRegs.GPAPUD.bit.GPIO13 = 1;    // Disable pull-up on GPIO13 (EPWM7A)
    GpioCtrlRegs.GPAODR.bit.GPIO13 = 1;
EDIS;
    GpioDataRegs.GPADAT.bit.GPIO13 = 1;

How can I configure the PGPIO13 pin to ENABLE diode emulation mode(DEM) for sync FET?

Thanks