一个应用，需要先使能PDB触发AD，过一段时间后关闭PDB触发AD。

使能PDB触发AD的指令如下：
InitAdcTriggerSource(ADC_INST,0);

InitAdcTriggerSource函数为：
void InitAdcTriggerSource(uint32_t adcInstance,uint32_t preChn)
{
  pdb_adc_pre_trigger_config_t pdbAdcTriggerConfig;
  pdb_user_config_t pdbUserConfig;
  pdb_clk_prescaler_div_mode_t divMode = kPdbClkPreDivBy64;
  uint32_t busClock, modValue;
  uint8_t preDivider = 1 << divMode;

  // get the bus clock freq which for PDB
  CLOCK_SYS_GetFreq(kBusClock, &busClock);

  // calculate for MOD value
  modValue = INPUT_SIGNAL_FREQ*NR_SAMPLES;
  modValue = busClock/preDivider/modValue*4;

  // init the pdb user config structure for
  // enable SW trigger, enable continuous mode,
  // set the correct MOD and DLY
  // Enable the sequency error interrupt.
  PDB_DRV_StructInitUserConfigForSoftTrigger(&pdbUserConfig);
  pdbUserConfig.continuousModeEnable = true;
  pdbUserConfig.pdbModulusValue = modValue;
  pdbUserConfig.intEnable = true;
  pdbUserConfig.seqErrIntEnable = true;
  pdbUserConfig.clkPrescalerDivMode = divMode;
  pdbUserConfig.multFactorMode = kPdbMultFactorAs1;

  // Initialize PDB driver
  PDB_DRV_Init(0, &pdbUserConfig);

  // Configure the PDB channel for ADC_adcInstance
  // disable BACK to BACK mode
  pdbAdcTriggerConfig.backToBackModeEnable = false;

  // enable pretrigger out
  pdbAdcTriggerConfig.preTriggerOutEnable = true;
  
  if(0==preChn)
  {
    pdbAdcTriggerConfig.delayValue = modValue/4;
  }

  if(1==preChn)
  {
    // the Pre-trigger A delay is set to 1/4 MOD,
    // the Pre-trigger B delay is set to 3/4 MOD,
    // so the trigger interval between A/B, B/A is same.
    pdbAdcTriggerConfig.delayValue = modValue*3/4;
  }
    // Configure the pre trigger A for ADC
//      PDB_DRV_EnableAdcPreTrigger(0, adcInstance, 0, &pdbAdcTriggerConfig);


  // Configure the pre trigger B for ADC
  PDB_DRV_EnableAdcPreTrigger(0, adcInstance, preChn, &pdbAdcTriggerConfig);

  // Configure SIM for ADC hw trigger source PDB
  SIM_HAL_SetAdcAlternativeTriggerCmd(gSimBaseAddr[0], adcInstance, false);

  // Trigger the PDB, let it go in continuous mode
  PDB_DRV_SoftTriggerCmd(0);
}

关闭PDB触发AD的指令如下：
PDB_DRV_DisableAdcPreTrigger(0, ADC_INST,0);

现在的情况是：
1、使能PDB触发AD，成功
2、关闭PDB触发AD，成功

问题：
一旦关闭PDB触发AD，程序停止运行，现象是UART无输出，GPIO输入输出无响应。

那么如何才能实现：
先使能PDB触发AD，过一段时间后关闭PDB触发AD，又不至于在关闭PDB触发AD后，程序停止运行？