MOTOROLA Chapter 35. Parallel I/O Ports 35-19
Part IV. Communications Processor Module
35.6 Interrupts from Port C

The port C lines associated with CDx and CTSx have a mode of operation where the pin

can be internally connected to the SCC/FCC but can also generate interrupts. Port C still

detects changes on the CTS and CD pins and asserts the corresponding interrupt request,

but the SCC/FCC simultaneously uses CTS and/or CD to automatically control operation.

This lets the user fully implement protocols V.24, X.21, and X.21 bis (with the assistance

of other general-purpose I/O lines).

To conÞgure a port C pin as a CTS or CD pin that connects to the SCC/FCC and generates

interrupts, these steps should be followed:

1. Write the corresponding PPARC bit with a 1 and PSORC bit with 0.

2. Write the corresponding PDIRC bit with a zero.

3. Set the SIEXR bit (in the interrupt controller) to determine which edges cause

interrupts.

PD8 FCC2: TxPrty
UTOPIA
SMC1: SMRXD GND BRG5: BRGO
PD7 SMC1: SMSYN GND FCC1: TxAddr[3]1
MPHY, master,
multiplexed polling
FCC2: TxAddr[4]
MPHY, master,
multiplexed polling
FCC1: TxAddr[3]2
MPHY, slave,
multiplexed polling
FCC1: TxClav22
MPHY, master, direct
polling
FCC2: TxAddr[1]
MPHY, slave,
multiplexed polling
GND
PD6 FCC1: TxD[4]
UTOPIA 16
IDMA1: DACK
PD5 FCC1: TxD[3]
UTOPIA 16
IDMA1: DONE3
Inout
(secondary option)
VDD
PD4 BRG8: BRGO TDM_D1: L1TSYNC/
GRANT3
(secondary option)
GND FCC3: RTS SMC2: SMRXD3
(secondary option)
GND
1MPHY address pins 3 and 4 (master mode) can come from FCC2, depending on CMXUAR programming. (See
Section 15.4.1, ÒCMX UTOPIA Address Register (CMXUAR).Ó)
2MPHY address pins 0Ð4 (slave mode) can come from FCC2, depending on CMXUAR programming. (See
Section 15.4.1, ÒCMX UTOPIA Address Register (CMXUAR).Ó)
3Available only when the primary option for this function is not used.

Table 35-8. Port D Dedicated Pin Assignment (PPARD = 1) (Continued)

Pin
Pin Function
PSORD = 0 PSORD = 1
PDIRD = 1 (Output) PDIRD = 0 (Input) Default
Input PDIRD = 1 (Output) PDIRD = 0 (Input, or
Inout if SpeciÞed)
Default
Input