GD的Timer2配置PB3时出不来波形

用GD进行Timer的PWM输出功能，发现PB3出不来波形。用的TIM2_CH1的PB3引脚。

GPIO配置如下：

```c
rcu_periph_clock_enable(RCU_GPIOB);
            gpio_pin_remap_config(GPIO_TIMER2_PARTIAL_REMAP,ENABLE);
          gpio_pin_remap_config(GPIO_SWJ_SWDPENABLE_REMAP,ENABLE);
            gpio_init(GPIOB,GPIO_MODE_AF_PP,GPIO_OSPEED_50MHZ,GPIO_PIN_3);

PWM配置

    timer_ocintpara.outputstate  = TIMER_CCX_ENABLE;
//    timer_ocintpara.outputnstate = TIMER_CCXN_DISABLE;
    timer_ocintpara.ocpolarity   = TIMER_OC_POLARITY_HIGH;
//    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(TIMER2,TIMER_CH_1,&timer_ocintpara);//TIMER1

    timer_channel_output_pulse_value_config(TIMER2,TIMER_CH_1,PeriodAssist*0.5f);//TIMER1  15999*0.5f  Car*0.2f
    timer_channel_output_mode_config(TIMER2,TIMER_CH_1,TIMER_OC_MODE_PWM0);
    timer_channel_output_shadow_config(TIMER2,TIMER_CH_1,TIMER_OC_SHADOW_ENABLE);

        
    /* auto-reload preload enable */
    timer_auto_reload_shadow_enable(TIMER2);
    /* auto-reload preload enable */
    timer_enable(TIMER2);