Motorola MCF5281, MCF5282 user manual Chapter Queued Analog-to-Digital Converter Qadc

Models: MCF5282 MCF5281

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Chapter 27

Queued Analog-to-Digital Converter (QADC)

The queued analog-to-digital converter (QADC) is a 10-bit, unipolar, successive approximation converter. Up to eight analog input channels can be supported using internal multiplexing. A maximum of 18 input channels can be supported in the expanded, externally multiplexed mode.

The QADC consists of an analog front-end and a digital control subsystem. The analog section includes input pins, an analog multiplexer, and sample and hold analog circuits.

The digital control section contains queue control logic to sequence the conversion process and interrupt generation logic. Also included are the periodic/interval timer, control and status registers, the conversion command word (CCW) table, random-access memory (RAM), and the result table RAM.

The bus interface unit (BIU) provides access to registers that configure the QADC, control the analog-to-digital converter and queue mechanism, and present formatted conversion results.

27.1 Features

Features of the QADC module include:

Internal sample and hold

Up to eight analog input channels using internal multiplexing

Up to four external analog multiplexers directly supported

Up to 18 total input channels with internal and external multiplexing

Programmable input sample time for various source impedances

Two conversion command word (CCW) queues with a total of 64 entries for setting conversion parameters of each A/D conversion

Subqueues possible using pause mechanism

Queue complete and pause interrupts available on both queues

Queue pointers indicating current location for each queue

Automated queue modes initiated by:

MOTOROLA

Chapter 27. Queued Analog-to-Digital Converter (QADC)

27-1

Page 585
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Motorola MCF5281, MCF5282 user manual Chapter Queued Analog-to-Digital Converter Qadc