Peripheral Pin Multiplexing (PPM) Module
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
18-9
18.3.2
PPM Signal Short Functionality
The MPC561/MPC563 devices have many modules that multiplex their functions onto shared signals. In
order to access those functions, the signals must be configured appropriately. However, choosing one
function can be at the cost of another function. The PPM makes more functions available simultaneously
by creating internal shorts that can activate functions that would otherwise require an external signal.
Internal signal shorts are enabled using the PPM short register, SHORT_REG.
18.3.2.1
TouCAN Shorting
There are three TouCAN modules on the MPC561/MPC563 devices. Using the PPM it is possible to
internally short the CNRX0 and CNTX0 signals of these three modules to increase message buffer
capacity. Three bits of the SHORT_REG register (SH_TCAN[0:2]), are allocated to enable four
combinations of shorting between the TouCAN modules. See
for information on these bit
descriptions.
When one TouCAN module is shorted to another, the CANRX signals and the CANTX signals of both
modules are shorted internally. Both modules continue to operate as normal but all transmit and receive
operations are done using only one pair of CANRX and CANTX signals. The CANRX and CANTX
signals of the other module are no longer under the control of the TouCAN module.
The C_TouCAN signals C_CNTX0 and C_CNRX0 are multiplexed signals. When C_TouCAN is shorted
with one or two other TouCAN modules, C_TouCAN no longer has control of these signals and so they
can be configured for another of the available functions. Refer to
Chapter 2, “Signal Descriptions
,” for
18.3.2.2
TPU Shorting
There are two TPU3 modules on the MPC561/MPC563 devices. Using the PPM, it is possible to internally
short channel A_TPUCH0 with B_TPUCH0 and channel A_TPUCH1 with B_TPUCH1. Two bits of the
SHORT_CH register (SH_TPU[1:0]) control the internal shorting. The input/output enable states of the
TPU channels themselves determine the effect that the short bits have on the TPU modules’ operation. See
for information on SHORT_CH[SH_TPU] bit descriptions.
The PPM only controls the internal shorting of TPU3 channels TPUCH0 and TPUCH1. TPU channels are
configured for input and output by the TPU ROM functions defined for them. Refer to
” for further information, and see
. If TPU_A and TPU_B channel 0
are shorted via SHORT_CH[SH_TPU] and one is set to ouput while the other is set to input, then the data
from the output channel will not appear on the pin of the input channel. This holds true if TPU_A and
TPU_B channel 1 are shorted via SHORT_CH[SH_TPU]. Connect an external device to the pin of the
module that has the channel function set to output.
18.3.2.3
ETRIG1 and ETRIG2
Each of the two QADC64E modules on the MPC561/MPC563 has an external trigger input signal that can
be used to trigger analog to digital conversions. Using the PPM, these external trigger inputs can be
sourced internally. Control for these short functions is found in SHORT_REG[SH_ET1] and
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...