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Serial Communication Modules
MOTOROLA
MPC801 USER’S MANUAL
16-15
16
NOTE
The LOOP bit must be zero for IrDA interface loopback testing.
UIPL—UART Interrupt Priority Level
This bit contains the priority request level of the UART interrupt that is sent to interrupt
level 0-7.
16.3 THE SERIAL CONTROLLER
The serial controller module serves both the serial peripheral interface and the
inter-integrated circuit (I
C) modules. Its primary responsibility is to act as an interface
between the U-bus and peripheral bus. It can also generate a reset signal to both the serial
peripheral interface and I
C modules, according to the PowerPC core commands.
2
2
16.3.1 Programming the Serial Controller
16.3.1.1 SERIAL CONTROLLER COMMAND REGISTER.
command (SECCOM) register controls the serial peripheral interface and I
modes.
The read/write serial controller
2
C operation
RST—Software Reset Command
This bit is set by the core and cleared by the serial controller. It is useful when the core wants
to reset the registers and state machines of the I
This command does not affect the parallel I/O registers.
2
C and serial peripheral interface channels.
Bits 1–7—Reserved
These bits are reserved and should be set to zero.
16.3.2 The Serial Peripheral Interface
The serial peripheral interface (SPI) allows the MPC801 to exchange data with other chips
in the MPC860 Family, the MC68360, MC68302, M68HC11, and M68HC05 microcontroller
families, as well as a number of peripheral devices. The serial peripheral interface is a
full-duplex, synchronous, character-oriented channel that supports a four-wire interface—
receive, transmit, clock and slave select.
The SPI block consists of transmitter and receiver sections, an independent baud rate
generator, and a control unit. The transmitter and receiver sections use the same clock that
is derived from the SPI baud rate generator in master mode and generated externally in
slave mode. During an SPI transfer, data is transmitted and received simultaneously.
Figure 4-2 below illustrates the serial peripheral interface block diagram.
SEECOM
BIT
0
1
2
3
4
5
6
7
FIELD
RST
RESERVED