SECTION 6QUEUED SERIAL MODULE
This section is an overview of queued serial module (QSM) function. Refer to the QSM
Reference Manual (QSMRM/AD) for complete information about the QSM.
6.1 General
The QSM contains two serial interfaces, the queued serial peripheral interface (QSPI)
and the serial communication interface (SCI). Figure 6-1 is a block diagram of the
QSM.
MISO/PQS0
MOSI/PQS1
SCK/PQS2
PCS0/SS/PQS3
PCS1/PQS4
PCS2/PQS5
PCS3/PQS6
QSPI
6
PORT QS
INTERFACE
LOGIC
IMB
TXD/PQS7
RXD
SCI
QSM BLOCK
Figure 6-1 QSM Block Diagram
The QSPI provides easy peripheral expansion or interprocessor communication
through a full-duplex, synchronous, three-line bus. Four programmable peripheral chip
selects can select up to 16 peripheral devices. A self-contained RAM queue allows up
to sixteen serial transfers of eight to sixteen bits each or transmission of a 256-bit data
stream without CPU intervention. A special wraparound mode supports continuous
sampling of a serial peripheral, with automatic QSPI RAM updating, for efficient inter-
facing to A/D converters.
MC68331
QUEUED SERIAL MODULE
MOTOROLA
6-1
USER’S MANUAL
MOTOROLA [ MOTOROLA ]
