CCS/TMS320F28377S: 28375S using GPIO42 and GPIO43 as I2C Issue

Tool/software: Code Composer Studio

Dear Sir/Madam.

I have tried two methods to initial I2C in GPIO42 and GPIO43.

If I use Ti function to configure them as below, it works well.

GPIO_SetupPinMux(42, 0, 6);
GPIO_SetupPinMux(43, 0, 6);

if I use register to configure them as below, it doesn't work.

//设置数据端口
GpioCtrlRegs.GPBPUD.bit.GPIO42 = 0; // Enable pullup on GPIO34
GpioCtrlRegs.GPBGMUX1.bit.GPIO42 = 1;
GpioCtrlRegs.GPBMUX1.bit.GPIO42 = 2; // GPIO42 = SDAA
GpioCtrlRegs.GPBQSEL1.bit.GPIO42 = 3; // Asynch input
//设置时钟端口
GpioCtrlRegs.GPBPUD.bit.GPIO43 = 0; // Enable pullup on GPIO35
GpioCtrlRegs.GPBGMUX1.bit.GPIO43 = 1;
GpioCtrlRegs.GPBMUX1.bit.GPIO43 = 2; // GPIO43 = SCLA
GpioCtrlRegs.GPBQSEL1.bit.GPIO43 = 3; // Asynch input

I don't know why.

Could you help me check that, Thanks!

Have a good day!

Frank