MPC823 datasheet(63/74 Pages) MOTOROLA

63 / 74 page

Communication Processor Module

MOTOROLA

MPC823 REFERENCE MANUAL

16-441

REV—Reverse Data

This bit determines the receive and transmit character bit order.

0 = Reverse data. Least-significant bit of the character transmitted and received first.

1 = Normal operation. Most-significant bit of the character transmitted and received

first.

M/S—Master/Slave

This bit configures the serial peripheral interface to operate as a master or slave.

0 = The serial peripheral interface is a slave.

1 = The serial peripheral interface is a master.

EN—Enable SPI

This bit enables serial peripheral interface operation. Configure the SPIMOSI, SPIMISO,

SPICLK, and SPISEL pins to connect to the serial peripheral interface, as described in

Section 16.14.6 The Port B Registers. When the EN bit is cleared, the serial peripheral

interface is in a reset state and consumes minimal power, which means the SPI baud rate

generator is not functioning and the input clock is disabled.

0 = The serial peripheral interface is disabled.

1 = The serial peripheral interface is enabled.

LEN—Character Length

This field specifies the number of bits in a character. These values must be between 4 and

16 bits. If you program a value less than 4 bits, erratic behavior will occur. If the value of LEN

is less than or equal to a byte, there will be LEN number of valid bits in every byte (8 bits) in

memory. On the other hand, if the value of LEN is greater than a byte, there is LEN number

of valid bits in every half-word (16 bits) in memory.

0011 = 4-bit character length.

0100 = 5-bit character length.

0101 = 6-bit character length.

0110 = 7-bit character length.

0111 = 8-bit character length.

•

1111 = 16-bit character length.

Note: You must not modify other bits of the SPMODE register when the EN bit is set.

MPC823 Datasheet(PDF) 63 Page - Motorola, Inc