TMS470R1B1M: can't config 6 PWM by using HET and can't read 24bit SPI data

i have two confused questions about TMS470.

First, i can't config 6 PWM by using HET. The code is list below. And there are only two PWM out(pin1 and pin2). How can i config HET to let pin4 output at the same time.

L00: CNT  {next=L01, reg=A, irq=OFF, max=0x214A, data=0}

L01: ECMP {next=L02, reg=A, hr_lr=HIGH, en_pin_action=ON, pin=CC1, action=PULSELO, irq=Off, data=0x10A5}

L02: ECMP {next=L03, reg=A, hr_lr=HIGH, en_pin_action=ON, pin=CC2, action=PULSELO, irq=Off, data=0x18f6}

L03: ECMP {next=L00, reg=A, hr_lr=HIGH, en_pin_action=ON, pin=CC4, action=PULSELO, irq=Off, data=0x18f6}

Second, i can't read 24bit SPI data. When i use F28335, i send 8 bit data 3 times to read 24 bit SPI data. And there is nothing wrong.

When i use TMS470, i send 8 bit data 3 times by using the following codes. It can't go in to the RTI interruption normally. Are there something wrong with the code? And how can i rectify my code to send 3 times SPI data?

void RTI_38k4_timer(){
    // 3 times send, it can't go to the interruption normally
    SPI1DAT0 = 0x00f0;
    ad_read[0] = SPI1BUF;
    for(int i = 0; i < 3; i++);
    SPI1DAT0 = 0x00f0;
    ad_read[1] = SPI1BUF;
    for(int i = 0; i < 3; i++);
    SPI1DAT0 = 0x00f0;
    ad_read[2] = SPI1BUF;

    // 1 times send, it go to the interruption normally
    SPI1DAT0 = 0x00f0;
    ad_read[0] = SPI1BUF;
}