Peripheral Pin Multiplexing (PPM) Module
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
18-3
18.3
Functional Description
In order to reduce the number of signals on the devices, many signals have multiple functions and each
signal must be configured for access to any of these functions. The PPM module is designed to increase
the availability of MPC561/MPC563 signal multiplexed functions. It can do this is two ways:
•
By implementing a parallel-to-serial communication protocol,
•
By implementing internal signal shorting.
18.3.1
PPM Parallel-to-Serial Communication Protocol
The PPM communication sub-modules, PPM_MUX and PPM_SHIFTER, transfer data between the
MPC561/MPC563 and external devices. The PPM reduces the number of connections between devices by
allowing certain internal modules of the MCU to transmit and receive data serially, where without PPM
those internal modules would have to transmit and receive data in parallel. Data is routed through the PPM
using internal multiplexers. Communication between the internal modules and the PPM remains a parallel
connection, but the PPM connects to external devices by a serial link. The PPM can be configured for
different data transfer rates and data formats.
S/U
3
RX_SHIFTER
0x30 5C1A
Data is shifted in from signals PPM_RX[0:1]
—
Reserved
0x30 5C1C
—
S/U
3
TX_DATA
0x30 5C1E
Data to be transmitted on PPM_TX[0:1]
—
Reserved
0x30 5C20
—
S/U
3
GPDO
0x30 5C22
General Purpose Data Out
S/U
3
GPDI
0x30 5C24
General Purpose Data In
S/U
3
SHORT_REG
0x30 5C26
Enables shorting of internal signals
S/U
3
SHORT_CH_REG
0x30 5C28
Enables shorting of transmit data channels
S/U
3
SCALE_TCLK_REG
0x30 5C2A
Establishes frequency of TCLK
—
Reserved
0x30 5C2C –
0x30 5C7F
—
1
Only accessible in Supervisor Mode.
2
This register is accessible in Test Mode only. Reads/Writes to this register when not in Test Mode will return TEA (bus
error access).
3
Accessible in Supervisor Mode and User Mode (when PPMMCR[SUPV]=0).
Table 18-1. PPM Memory Map (continued)
Access
Register Name
Address
Usage
Summary of Contents for MPC561
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