GD32E230PWM输出波形

请问GD32E230PWM输出波形怎么调成直上直下的

void timer_config(void)
{
timer_oc_parameter_struct timer_ocintpara;
    timer_parameter_struct timer_initpara;

    rcu_periph_clock_enable(RCU_TIMER16);

    timer_deinit(TIMER16);

    /* TIMER configuration */
    timer_initpara.prescaler         = 7200; 
    timer_initpara.alignedmode       = TIMER_COUNTER_EDGE;
    timer_initpara.counterdirection  = TIMER_COUNTER_UP;
    timer_initpara.period            = 4000; 
    timer_initpara.clockdivision     = TIMER_CKDIV_DIV1;
    timer_initpara.repetitioncounter = 0;
    timer_init(TIMER16,&timer_initpara);

    /* configurate CH0 in PWM mode0 */
    timer_ocintpara.outputstate  = TIMER_CCX_ENABLE;
    timer_ocintpara.outputnstate = TIMER_CCXN_DISABLE;
    timer_ocintpara.ocpolarity   = TIMER_OC_POLARITY_HIGH;//极性为高 占空比内高电平
    timer_ocintpara.ocnpolarity  = TIMER_OCN_POLARITY_HIGH;
    timer_ocintpara.ocidlestate  = TIMER_OC_IDLE_STATE_LOW;
    timer_ocintpara.ocnidlestate = TIMER_OCN_IDLE_STATE_LOW;

    timer_channel_output_config(TIMER16,TIMER_CH_0,&timer_ocintpara);

    timer_channel_output_pulse_value_config(TIMER16,TIMER_CH_0,1000); // 50% duty
    timer_channel_output_mode_config(TIMER16,TIMER_CH_0,TIMER_OC_MODE_PWM0);
    timer_channel_output_shadow_config(TIMER16,TIMER_CH_0,TIMER_OC_SHADOW_DISABLE);

    /* auto-reload preload enable */
    timer_auto_reload_shadow_enable(TIMER16);
//    timer_automatic_output_enable(TIMER16);
    timer_primary_output_config(TIMER16,ENABLE);
    /* auto-reload preload enable */
    timer_enable(TIMER16);
}