【需求描述】
汽车电子类产品（如BCM）一般要求正常工作电压为9~16V，CAN总线活跃电压范围为7~18V。有些负载如门锁、转向灯则不限制9~16V。
【设计思路】
STEP1：
板载CAN transceiver（如TJA1043）工作电压范围为[4.5 5.5]V，典型值为5V。
板载5VLDO(如TPS7B69xx)稳定输出5V的输入电压范围为[5.8 40V]。
STEP2:
车载蓄电池规格为12V。
STEP3:
结合需求与硬件特性，可作出电压状态划分图如下。
其中模式Low与Normal之间的滞洄区间(0.5V/200ms)是指：当电压从高于9V变化到低于8.5V时，电压低于8.5V持续时间多于200ms，电源模式从Normal模式切换到Low模式；当电压从低于9V变化到高于9V时，电压高于9V持续时间多于200ms，电源模式从Low模式切换到Normal模式。
设计滞洄区间的目的：防止干扰造成的电压变化执行到负载上。
【编码实现】
appPowerManage.c /***************************************** * prototype : scan voltage mode * input : none * output : none * return : voltage mode *****************************************/ U8 pmmSysCheck_SystermVoltageScan(void) { U16 pmmSystermVoltTemp; U8 pmmSystermVoltModeNew; pmmSystermVoltTemp = Adh_GetLogicalValue(ADH_KL30_DUT); /* sys voltage mode parse */ if ((pmmSystermVoltTemp >= sysVoltageCfgPara.sysLowVoltThreshold) &&(pmmSystermVoltTemp <= sysVoltageCfgPara.sysHighVoltThreshold) )// 9.0V ~ 16.0V { pmmSystermVoltModeNew = PMM_SYS_VOL_NORMAL; } else if(pmmSystermVoltTemp > sysVoltageCfgPara.sysHighVoltThreshold) // > 16.0V { if( pmmSystermVoltTemp < (sysVoltageCfgPara.sysHighVoltThreshold + SYS_VOLT_BACK_Threshold) ) //16.0V ~ 16.5 { pmmSystermVoltModeNew = PMM_SYS_VOL_HIGH_HYST; } else if( pmmSystermVoltTemp <= (sysVoltageCfgPara.sysOverVoltThreshold - SYS_VOLT_BACK_Threshold) )//16.5V ~ 17.5V { pmmSystermVoltModeNew = PMM_SYS_VOL_HIGH; } else if(pmmSystermVoltTemp < sysVoltageCfgPara.sysOverVoltThreshold) //17.5V ~ 18.0V { pmmSystermVoltModeNew = PMM_SYS_VOL_OVER_HYST; } else // >18.0 { pmmSystermVoltModeNew = PMM_SYS_VOL_OVER; } } else // < 9.0V { if( pmmSystermVoltTemp > (sysVoltageCfgPara.sysLowVoltThreshold - SYS_VOLT_BACK_Threshold) ) //8.5V ~ 9.0V { pmmSystermVoltModeNew = PMM_SYS_VOL_LOW_HYST; } else if( pmmSystermVoltTemp >= (sysVoltageCfgPara.sysStopVoltThreshold + SYS_VOLT_BACK_Threshold) )//6.5V ~ 8.5V { pmmSystermVoltModeNew = PMM_SYS_VOL_LOW; } else if(pmmSystermVoltTemp > sysVoltageCfgPara.sysStopVoltThreshold) //6.0V ~ 6.5V { pmmSystermVoltModeNew = PMM_SYS_VOL_STOP_HYST; } else // < 6.0V { pmmSystermVoltModeNew = PMM_SYS_VOL_STOP; } } return pmmSystermVoltModeNew; } /***************************************** * prototype : classify voltage mode * input : none * output : none * return : voltage mode *****************************************/ U8 pmmSysCheck_SystermVoltageModeGet(void) { U8 SystermVoltModeTemp; static U8 SystermVoltModeLast = PMM_SYS_VOL_NORMAL; SystermVoltModeTemp = pmmSysCheck_SystermVoltageScan(); /* state flow for Devices Voltage */ if(SystermVoltModeTemp == PMM_SYS_VOL_OVER_HYST) { if(SystermVoltModeLast == PMM_SYS_VOL_OVER ) { SystermVoltModeTemp = PMM_SYS_VOL_OVER; } else { SystermVoltModeTemp = PMM_SYS_VOL_HIGH; } } else if(SystermVoltModeTemp == PMM_SYS_VOL_HIGH_HYST) { if( (SystermVoltModeLast == PMM_SYS_VOL_HIGH) || (SystermVoltModeLast == PMM_SYS_VOL_OVER) ) { SystermVoltModeTemp = PMM_SYS_VOL_HIGH; } else { SystermVoltModeTemp = PMM_SYS_VOL_NORMAL; } } else if(SystermVoltModeTemp == PMM_SYS_VOL_LOW_HYST) { if( (SystermVoltModeLast == PMM_SYS_VOL_LOW)||(SystermVoltModeLast == PMM_SYS_VOL_STOP) ) { SystermVoltModeTemp = PMM_SYS_VOL_LOW; } else { SystermVoltModeTemp = PMM_SYS_VOL_NORMAL; } } else if(SystermVoltModeTemp == PMM_SYS_VOL_STOP_HYST) { if(SystermVoltModeLast == PMM_SYS_VOL_STOP ) { SystermVoltModeTemp = PMM_SYS_VOL_STOP; } else { SystermVoltModeTemp = PMM_SYS_VOL_LOW; } } else { ; //not in "MM_SYS_VOL_XXX_HYST" } SystermVoltModeLast = SystermVoltModeTemp; return SystermVoltModeTemp; } /***************************************** * prototype : voltage mode change debounce * input : none * output : none * return : none *****************************************/ void pmmSysCheck_SystermVoltageModeHandle(void) { U8 SystermVoltModeNew; static U8 SystermVoltModeOld = PMM_SYS_VOL_UNKNOW; static U8 SystermVoltDounceCnt = 0; SystermVoltModeNew = pmmSysCheck_SystermVoltageModeGet(); /* add debouce process */ if(SystermVoltModeNew != SystermVoltModeOld) { SystermVoltModeOld = SystermVoltModeNew; SystermVoltDounceCnt = 0; } else { if(g_inSystemVoltageModeSts != SystermVoltModeOld) { SystermVoltDounceCnt++; if(SystermVoltDounceCnt >= PMM_SYS_VOLTAGE_DEBOUNCE_COUNT) { g_inSystemVoltageModeSts = SystermVoltModeOld; SystermVoltDounceCnt = 0; } } } } appPowerManage_Private.h enum { PMM_SYS_VOL_NORMAL = 0, PMM_SYS_VOL_STOP, PMM_SYS_VOL_LOW, PMM_SYS_VOL_HIGH, PMM_SYS_VOL_OVER, PMM_SYS_VOL_INVALID, PMM_SYS_VOL_STOP_HYST, PMM_SYS_VOL_LOW_HYST, PMM_SYS_VOL_HIGH_HYST, PMM_SYS_VOL_OVER_HYST, PMM_SYS_VOL_UNKNOW = 0xffu }; typedef struct { /*normal configuration*/ U16 sysLowVoltThreshold; //0.1v U16 sysHighVoltThreshold; //mv U16 sysOverVoltThreshold; //mv U16 sysStopVoltThreshold; //mv }sysVoltageCfgType; #define SYS_VOLT_BACK_Threshold (500u) #define PMM_SYS_VOLTAGE_DEBOUNCE_COUNT (10u) //20ms*10=200ms const sysVoltageCfgType sysVoltageCfgPara = { /*normal configuration*/ 8500, 16500, 18000, 6000, };