Peripheral Pin Multiplexing (PPM) Module
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
18-11
18.4.1.1
Entering Stop Mode
The PPM module cannot, and should not, be put into stop mode while either the transmit or receive
operation is enabled in PPMPCR[ENTX] and/or PPMPCR[ENRX]. Furthermore, it should not be put into
stop mode if it is operating in continuous mode. In this case it should be switched to single transfer mode
first.
The following steps should be taken to ensure that stop mode is entered safely and without loss of data:
1. If the PPM is operating in continous mode
— switch to single transfer mode by clearing PPMPCR[CM]=0.
2. If the PPM is enabled for transmit or receive
— set PPMPCR[STR] (TDM or SPI mode)
— Disable both PPMPCR[ENTX] and PPMPCR[ENRX]
— Wait until PPMPCR[STR] is cleared by the PPM module. This will be done when the next data
frame has been sent or received.
3. If the PPM is not enabled for transmit or receive
— Clear PPMPCR[STR] if necessary
4. Set PPMMCR[STOP]
When PPMMCR[STOP] is set, the PPM module enters stop mode and the PPM module clocks will
be stopped. While in stop mode, none of the PPM registers will be accessible, except for the
PPMPCR register.
If the STOP bit is clear, stop mode is disabled.
Table 18-2. PPMMCR Bit Descriptions
Bits
Name
Description
0
STOP
Stop Mode Enable. When the STOP bit is set and the PPM enters Stop Mode, the PPM module
clocks will be stopped. The PPM will only respond to accesses to the PPMMCR register. The
STOP bit can only be set when the PPM is disabled, (i.e., PPMPCR[ENTX] = 0
and
PPMPCR[ENRX] = 0). Writing to the STOP bit while either TX or RX is enabled will result in a
TEA (bus error access).
0 PPM clocks enabled
1 PPM clock disabled – PPM in Stop Mode.
1:7
—
Reserved
8
SUPV
Supervisor/User Data Space. The SUPV bit places the PPM registers in either Supervisor or
User Data Space.
0 Access to PPMMCR, TX_CONFIG1/2, RX_CONFIG1/2 is restricted to supervisor-only.
Access to all other PPM registers is unrestricted.
1 All PPM registers are accessible in supervisor-only data space.
9:15
—
Reserved
Summary of Contents for MPC561
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