MSH命令创建定时器，使用完成后删除，再次使用MSH命令创建无法运行

void System_VddPowerManager(void *param)
{
    rt_uint16_t Vdd_PowerVoltageAverage;
    ADC_Set_RefVoltage(ADC_VDD_VSS_REFERENCE_VOLTAGE);
    Vdd_PowerVoltageAverage = ADC_Converse(ADC_INTERREFVOLT, 10, NULL);
    Vdd_PowerDetectCount++;
    //内部基准电压为1.45V,
    Vdd_PowerVoltageAverage = (1450UL*4095UL/Vdd_PowerVoltageAverage);
    rt_kprintf ("system vdd voltage value: %d;\n", Vdd_PowerVoltageAverage);
}

power_timer = rt_timer_create("power timer", System_VddPowerManager,
                                RT_NULL, 50, RT_TIMER_FLAG_PERIODIC);
if (1){//power_timer != RT_NULL) {
    rt_timer_start(power_timer);
    while (Vdd_PowerDetectCount < 5) {
        rt_thread_mdelay(100);
    }
    rt_timer_stop(power_timer);
    rt_timer_delete(power_timer);
}
return 0;