MULTICHANNEL COMMUNICATION INTERFACE
M68HC16 Z SERIES
10-4
USER’S MANUAL
Select a value for INTV so that each MCCI interrupt vector corresponds to one of the
user-defined vectors ($40–$FF). Refer to the
CPU16 Reference Manual (CPU16RM/
AD) for additional information on interrupt vectors.
10.2.2 Pin Control and General-Purpose I/O
The eight pins used by the SPI and SCI subsystems have alternate functions as gen-
eral-purpose I/O pins. Configuring the MCCI submodule includes programming each
pin for either general-purpose I/O or its serial interface function. In either function,
each pin must also be programmed as input or output.
The MCCI data direction register (MDDR) assigns each MCCI pin as either input or
output. The MCCI pin assignment register (MPAR) assigns the MOSI, MISO, and SS
pins as either SPI pins or general-purpose I/O. (The fourth pin, SCK, is automatically
assigned to the SPI whenever the SPI is enabled, for example, when the SPE bit in
the SPI control register is set.) The receiver enable (RE) and transmitter enable (TE)
bits in the SCI control registers (SCCR0A, SCCR0B) automatically assign the associ-
ated pin as an SCI pin when set or general-purpose I/O when cleared.
summarizes how pin function and direction are assigned.
10.3 Serial Peripheral Interface (SPI)
The SPI submodule communicates with external peripherals and other MCUs via a
synchronous serial bus. The SPI is fully compatible with the serial peripheral interface
systems found on othe
Freescale
devices, such as the M68HC11 and M68HC05 fam-
ilies. The SPI can perform full duplex three-wire or half duplex two-wire transfers. Se-
rial transfer of eight or sixteen bits can begin with the MSB or LSB. The system can be
configured as a master or slave device.
shows a block diagram of the SPI.
Table 10-2 Pin Assignments
Pin
Function Assigned By
Direction Assigned By
TXDA/PMC7
TE bit in SCCR0A
MMDR7
RXDA/PMC6
RE bit in SCCR0A
MMDR6
TXDB/PMC5
TE bit in SCCR0B
MMDR5
RXDB/PMC4
RE bit in SCCR0B
MMDR4
SS/PMC3
SS bit in MPAR
MMDR3
SCK/PMC2
SPE bit in SPCR
MMDR2
MOSI/PMC1
MOSI bit in MPAR
MMDR1
MISO/PMC0
MISO bit in MPAR
MMDR0
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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