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MC68341 USER’S MANUAL
MOTOROLA
Half Duplex, Two-Wire Synchronous Transfers
Master or Slave Operation
Programmable Master Bit Rates
Programmable Clock Polarity and Phase
End-of-Transmission Interrupt Flag
Master-Master Mode Fault Flag
Easily Interfaces to Simple Expansion Parts (A/D converters, EEPROMS, display
drivers, etc.)
QSPI-Enhanced features are as follows:
Programmable Queue—Up to 16 Preprogrammed Transfers
Programmable Peripheral Chip Selects—Two Pins Select Up to Four SPI Chips
Wraparound Transfer Mode—For Autoscanning of Serial A/D (or Other) Peripherals,
With No CPU Overhead
Programmable Transfer Length—From 8–16 Bits Inclusive
Programmable Transfer Delay—From 1
s to 0.5 ms (at 16.78 MHz)
Programmable Queue Pointer
Continuous Transfer Mode—Up to 256 Bits
9.5.1.1 PROGRAMMABLE QUEUE. A programmable queue allows the QSPI to perform
up to 16 serial transfers without CPU intervention. Each transfer corresponds to a queue
entry containing all the information needed by the QSPI to independently complete one
serial transfer. This unique feature greatly reduces CPU/QSPI interaction, resulting in
increased CPU and system throughput.
9.5.1.2 PROGRAMMABLE PERIPHERAL CHIP SELECTS. Two peripheral chip-select
pins allow the QSPI to access up to four independent peripherals by decoding the two
peripheral chip-select signals. Two independent peripherals can be selected by direct
connection to a chip-select pin. The peripheral chip selects simplify interfacing to two
peripherals by providing dedicated peripheral chip-select signals, alleviating the need for
CPU intervention.
9.5.1.3 WRAPAROUND TRANSFER MODE. Wraparound transfer mode allows
automatic, continuous re-execution of the preprogrammed queue entries. Newly
transferred data replaces previously transferred data. Wraparound simplifies interfacing
with A/D converters by automatically providing the CPU with the latest A/D conversions in
the QSPI RAM. Consequently, serial peripherals appear as memory-mapped parallel
devices to the CPU.
9.5.1.4 PROGRAMMABLE TRANSFER LENGTH. The number of bits in a serial transfer
is programmable from 8 to 16 bits, inclusive. For example, 10 bits could be used for
communicating with an external 10-bit A/D converter. Likewise, a vacuum fluorescent
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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