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MPC555 / MPC556
QUEUED SERIAL MULTI-CHANNEL MODULE
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
14-1
SECTION 14
QUEUED SERIAL MULTI-CHANNEL MODULE
14.1 Overview
The queued serial multi-channel module (QSMCM) provides three serial communica-
tion interfaces: the queued serial peripheral interface (QSPI) and two serial communi-
cations interfaces (SCI1 and SCI2). These submodules communicate with the CPU
via a common slave bus interface unit (SBIU).
The QSPI is a full-duplex, synchronous serial interface for communicating with periph-
erals and other MCUs. It is enhanced from the original SPI in the QSMCM (queued
serial module) to include a total of 160 bytes of queue RAM to accommodate more re-
ceive, transmit, and control information. The QSPI is fully compatible with the SPI sys-
tems found on other Motorola devices.
The dual, independent SCIs are used to communicate with external devices and other
MCUs via an asynchronous serial bus. Each SCI is a full-duplex universal asynchro-
nous receiver transmitter (UART) serial interface. The original QSMCM SCI is en-
hanced by the addition of an SCI and a common external baud clock source.
The SCI1 has the ability to use the resultant baud clock from SCI2 as the input clock
source for the SCI1 baud rate generator. Also, the SCI1 has an additional mode of op-
eration that allows queuing of transmit and receive data frames. If the queue feature
is enabled, a set of 16 entry queues is allocated for the receive and/or transmit oper-
ation.
14.2 Block Diagram
depicts the major components of the QSMCM.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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