第06章 系统控制(时钟-振荡器-看门狗-PLL)

第6章时钟与系统控制1时钟和系统控制2振荡器和锁相环3看门狗电路4低功耗模块本讲内容1时钟和系统控制2振荡器和锁相环3看门狗电路4低功耗模块时钟与系统控制时钟与系统控制框图时钟与系统控制的寄存器外设时钟控制寄存器

PCLKCR@701ChModuleEnableClockBit0=disable1=enable0reservedreserved1234567EVAENCLKEVBENCLKreservedADCENCLKreservedreservedECANENCLKSPIAENCLKSCIBENCLK89101112131415reservedSCIAENCLKMCBSPENCLKreservedreservedHSPCLKLSPCLK高/低速外设时钟预定标寄存器

HISPCP@701Ah/LOSPCP@701Bh0215-3HSPCLKreservedH/LSPCLK2H/LSPCLK1H/LSPCLK0PeripheralClockFrequency000 SYSCLKOUT/1001 SYSCLKOUT/2(defaultHISPCP)010 SYSCLKOUT/4(defaultLOSPCP)011 SYSCLKOUT/6100 SYSCLKOUT/8101 SYSCLKOUT/10110 SYSCLKOUT/12111 SYSCLKOUT/140215-3LSPCLKreserved1时钟和系统控制2振荡器和锁相环3看门狗电路4低功耗模块时钟与系统控制C28xOsc/PLL时钟模块

PLLCR@7021hDIV3DIV2DIV1DIV0 ClockFrequency(CLKIN)0000 OSCCLKx1/2(noPLL)0001 OSCCLKx1/20010 OSCCLKx2/20011 OSCCLKx3/20100 OSCCLKx4/20101 OSCCLKx5/20110 OSCCLKx6/20111 OSCCLKx7/21000 OSCCLKx8/21001 OSCCLKx9/21010 OSCCLKx10/2PLLCRbits15:4reservedcrystalPLLClockModule4-bitPLLSelectX1/CLKINX2XTALOSCWatchdogModule/2PLLCLKOSCCLK•C28xCoreCLKINMUXXF_XPLLDIS10SYSCLKOUTHISPCPLOSPCPHSPCLKLSPCLK••1、PLL旁路2、PLL使能1时钟和系统控制2振荡器和锁相环3看门狗电路4低功耗模块时钟与系统控制看门狗模块如果CPU崩溃，则复位系统看门狗计数器独立于CPU如果计数器溢出则复位或中断被触发为防止计数器溢出，CPU必须周期性的向看门狗WDKEY寄存器写入0X55+0XAA序列在复位之后(10M外部时钟)3ms之内看门狗必须被启用或者禁止（对不对？）看门狗模块6-BitFree-RunningCounterCLR/2/4/8/16/32/64OSCCLKSystemReset101100011010001000111110••••8-BitWatchdogCounterCLROne-CycleDelayWatchdogResetKeyRegister55+AADetector•GoodKeyBadKey101••••//33WDCR.2-0WDCR.6WDPSWDDISWDCR.7WDFLAGWDCNTR.7-0WDKEY.7-0WDCR.5-3WDCHK2-0BadWDCRKey/512OutputPulseWDRSTWDINTSCSR.1WDENINT•••SCSR.0WDOVERRIDE看门狗控制寄存器

WDCR@7029hWDFLAGWDDIS76543210WDCHK1WDCHK0WDPS2WDPS1WDPS0WDCHK2LogicCheckBitsWriteas101orresetimmediatelytriggeredWDPrescaleSelectionBitsWatchdogDisableBit(FunctionsonlyifWDOVERRIDEbitinSCSRisequalto1)reserved15-8 WDFlagBitGetssetwhentheWDcausesaresetWritinga1clearsthisbitWritinga0hasnoeffect看门狗复位密钥寄存器

WDKEY@7025h允许写入的数值:55h–在AAH之后的写入55使能计数器AAh–如果复位使能则计数器清零写入其他任何值将复位CPU或触发WDINT中断？reservedD776543210D6D5D4D3D2D1D015-8WDKEY写操作SequentialStep1234567891011ValueWrittentoWDKEYAAhAAh55h55h55hAAhAAh55hAAh55h23hResultNoactionNoactionWDcounterenabledforresetonnextAAhwriteWDcounterenabledforresetonnextAAhwriteWDcounterenabledforresetonnextAAhwriteWDcounterisresetNoactionWDcounterenabledforresetonnextAAhwriteWDcounterisresetWDcounterenabledforresetonnextAAhwriteCPUresettriggeredduetoimproperwritevalue系统控制和状态寄存器

SCSR@7022hWDOverride(protectbit)AfterRESET-bitgivesuserabilitytodisableWDbysettingWDDISbit=1inWDCR

clearonlybitanddefaultsto1afterreset0=protectsWDfrombeingdisabledbys/w

bitcannotbesetto1bys/w(clear-onlybywriting1)1=(defaultvalue)allowsWDtobedisabledusingWDDISbitinWDCR

oncecleared,bitcannotsetto1bys/w01215-3WDOVERRIDEWDENINTWDINTSreservedWDEnableInterruptWDInterruptStatus(readonly)0=active1=notactive0=WDgeneratesaDSPreset1=WDgeneratesaWDINTinterrupt1时钟和系统控制2振荡器和锁相环3看门狗电路4低功耗模块时钟与系统控制低功耗模式LowPowerModeCPULogicClockPeripheralLogicClockWatchdogClockPLL/OSCNormalRunIDLESTANDBYHALTonoffoffoffononoffoffonononoffonononoff低功耗方式控制0寄存器

LPMCR0@701Eh017-215-8LPM0LPM1QUALSTDBYreservedLowPowerModeEntering1.SetLPMbits2.Enabledesiredexitinterrupt(s)3.ExecuteIDLEinstruction4.ThePowerdownsequenceofthehardwaredependsonLPmodeLowPowerModeSelection00=Idle01=Standby1x=HaltQualifybeforewakingfromSTANDBYmode000000=2OSCCLKs000001=3OSCCLKs111111=65OSCCLKS.........低功耗模式控制1寄存器

LPMCR1@701FhWakedevicefromSTANDBYmode0=disable1=enable0WDINTSCIRXBC2TRIPC5TRIPT3CTRIP123456789101112131415XINT1XNMIT2CTRIPT1CTRIPC3TRIPT4CTRIPC4TRIPC1TRIPC6TRIPSCIRXACANRXAIDLESTANDBYHALTRESETyesyesyesExternalorWakeupInterruptsye