MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
30-1
Chapter 30
Serial Peripheral Interface (SPI)
The serial peripheral interface (SPI) allows the MPC885 to exchange data between other MPC885 chips,
the MC68360, the MC68302, the M68HC11 and M68HC05 microcontroller families, and peripheral
devices such as EEPROMs, real-time clocks, A/D converters, and ISDN devices.
The SPI 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, which is derived from the SPI baud rate generator in master mode and generated externally in slave
mode. During an SPI transfer, data is sent and received simultaneously.
Because the SPI receiver and transmitter are double-buffered, as shown in
Figure 30-1
, the effective FIFO
size (latency) is 2 characters. The SPI’s msb is shifted out first. When the SPI is disabled in the SPI mode
register (SPMODE[EN] = 0), it consumes little power.
Figure 30-1. SPI Block Diagram
30.1
Features
The following is a list of the SPI’s main features:
•
Four-signal interface (SPIMOSI, SPIMISO, SPICLK, and SPISEL)
•
Full-duplex operation
•
Works with data characters from 4 to 16 bits long
•
Supports back-to-back character transmission and reception
SPI Mode Register
Transmit_Register
Receive_Register
Counter
Shift_Register
SPIBRG
Pins Interface
BRGCLK
SPIMOSI
SPISEL
SPIMISO
SPICLK
TxD
RxD
IN_CLK
IMB
Peripheral Bus
Summary of Contents for PowerQUICC MPC870
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Page 118: ...MPC885 Overview MPC885 PowerQUICC Family Reference Manual Rev 2 1 20 Freescale Semiconductor ...
Page 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
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Page 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Page 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
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Page 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
Page 1386: ...Revision History MPC885 PowerQUICC Family Reference Manual Rev 2 I 2 Freescale Semiconductor ...