Reaction Module (REACM)MPC5644A Microcontroller Reference Manual, Rev. 6722 Freescale SemiconductorFigure 23-22. Hold-off timer bank block diagramThe Modulation Control Word generates the address for the Hold-off Timer bank which then generates thehold-off value for the channels. The channel that addressed the Modulation Word captures the 12-bit valuestoring it in the channel Hold-off timer. In Figure 23-22 channel CH0 is requesting access to theModulation Word thus receiving the hold-off value from the Hold-off Timer Bank. Each reaction channelhas its own internal hold-off timer.23.4.5 Threshold bank and comparatorThe Threshold bank and comparator contains the threshold levels to be compared against the ADC results.This submodule also performs the comparison between the ADC result and the selected threshold value.The Threshold bank can be programmed with up to 64 threshold values depending on the configurationdefined during the module integration.An ADC result received from the on-chip ADC is connected to the ADC router and then to the comparator.See Figure 23-23. This result stays at the comparator input until the Reaction Channel and ModulationControl Word selects the address of the Threshold value. The THRESPT field in the Modulation ControlWord submodule is used as the address for the Threshold Bank. Note that if Threshold/Thresholdmodulation mode is used two comparisons need to be executed with two different Threshold values. Afterthe first comparison is made the THRESPT pointer is incremented and a new comparison is done:• First comparison: COMP = ADC_DATA THRESHOLD_VALUE[THRESPT]• Second comparison: COMP = ADC_DATA < THRESHOLD_VALUE[THRESPT + 1]The COMP (comparison result) is routed to the channel selected by the received TAG. Once havingreceived the comparison result the channel takes the appropriate actions in order to execute the modulationmode as defined by the modulation control word.TIMERBANKHOLD-OFFHDOFFPTHold-off time value[11:0]124(to all Reaction channels)CPUModulationControlhdt hdt hdtCH0 CH1 CHn16Hold-off timerReaction Channels
