
MC68F375
QUEUED ANALOG-TO-DIGITAL CONVERTER MODULE-64
MOTOROLA
REFERENCE MANUAL
Rev. 25 June 03
5-2
5.2 Features
The QADC64 module offers the following features:
Internal sample and hold
Up to 16 analog input channels using internal multiplexing
Directly supports up to four external multiplexers (for example, the MC14051)
Up to 41 total input channels with internal and external multiplexing
Programmable input sample time for various source impedances
Two conversion command queues with a total of 64 entries
Sub-queues possible using pause mechanism
Queue complete and pause software interrupts available on both queues
Queue pointers indicate current location for each queue
Automated queue modes initiated by:
— External edge trigger [queues 1 and 2] and gated mode [queue 1 only]
— Periodic/interval timer, within QADC64 module [queues 1 and 2]
— Software command [queues 1 and 2]
Single-scan or continuous-scan of queues
64 result registers
Output data readable in three formats:
— Right-justified unsigned
— Left-justified signed
— Left-justified unsigned
Unused analog channels can be used as digital ports
5.3 QADC64 Pin Functions
The QADC64 module uses the following 36 pins:
2 analog reference pins, to which all analog input voltages are scaled
16 analog input pins with 3 analog inputs multiplexed with multiplex address sig-
nals and 2 multiplexed with the on-chip analog multiplexer inputs
16 analog input pins through the on-chip AMUX circuit
2 analog power pins (VDDA, VSSA)
2 trigger pins shared with AN[55:56]/PQA[3:4]
The 16 channel/port pins can support up to 41 channels when external multiplexing is
used (including internal channels). All of the channel pins can also be used as general-
purpose digital port pins.
The following paragraphs describe QADC64 pin functions. Figure 5-2 shows the
QADC64 module pins.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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