Signal DescriptionMPC5566 Microcontroller Reference Manual, Rev. 2Freescale Semiconductor 2-32.2 External Signal DescriptionsThis section summarizes the external signal functions, the electrical characteristics, and pad configurationsettings for this device. The signal properties and electrical characteristics are set in the System IntegrationUnit (SIU) Pad Configuration (PCR) registers.2.2.1 Multiplexed SignalsSignal functions are multiplexed to each ball on the BGA in a function hierarchy: Primary, Main Primary,Alternate, Second Alternate, and General Purpose Input/Output (I/O). For example, in the signalPCSA[3]_SIND_GPIO[99], the primary signal function is PCSA[3], the first alternate signal function isSIND, and the GPIO function is a generic General Purpose I/O signal. Multiplexing signal functionsallows for more flexibility when configuring the device, as well as providing compatibility with otherdevices in the MPC5500 product family.The primary signal function name is used in the Ball Grid Array (BGA) map to identify the location of theball, however, the primary signal function is not always valid for all devices. As shown in Figure 2-2, whenthe primary signal function is not available on the device, a dash appears in the following Signal tablecolumns: Signal Functions, P/A/G, and I/O Type.Figure 2-2. Primary Function Not Available on DeviceThe entries in the P/A/G column designate the position in the signal function hierarchy for multiplexedfunctions. These symbols correspond to binary values for the Pin Assignment (PA) field in the SIU_PCRregisters that determine the active signal function. The PA field is from 1- to 3-bits wide, depending on thePCR register. Figure 2-3 explains the symbol definitions used in the P/A/G column for Table 2-1.Signal Names Signal FunctionsP/A/GI/OType VoltagePadTypeSDuringResetPCSA[3]_ 21SIND_GPIO[99]—DSPI D data inputGPIO—AG—II/OVDDEH6 MH – / UpPrimary FunctionsSecondary FunctionsGPIO Functions areNo primaryFootnoteTable Table 4-1. Signal Propertiesare listed Firstare alternate functionsgeneral functions listed Lastfunction available
