8Analog Interface
8 – 1
8.1 OVERVIEW
The ADSP-21msp58 and ADSP-21msp59 processors include an analog
signal interface consisting of a 16-bit sigma-delta A/D converter, a 16-
bit sigma-delta D/A converter, and a set of memory-mapped control
and data registers. The analog interface offers the following features:
• linear-coded 16-bit sigma-delta ADC
• linear-coded 16-bit sigma-delta DAC
• on-chip anti-aliasing and anti-imaging filters
• 8 kHz sampling frequency
• programmable gain for DAC and ADC
• on-chip voltage reference
The analog interface provides a complete analog front end for high
performance voiceband DSP applications. The ADC and DAC operate
at a fixed sampling rate of 8 kHz. The inclusion of on-chip anti-aliasing
and anti-imaging filters, 16-bit sigma-delta converters, and
programmable gain amplifiers ensures a highly integrated solution to
voiceband analog processing requirements. Sigma-delta conversion
technology eliminates the need for complex off-chip anti-aliasing filters
and sample-and-hold circuitry.
The ADSP-21msp58 and ADSP-21msp59 contain the same analog
interface—they differ only in the amount of on-chip memory. Refer to
the ADSP-21msp58/59 Data Sheet for detailed analog performance
specifications.
The analog interface of the ADSP-21msp58/59 is operated by using
several data-memory-mapped control and data registers. The ADC
and DAC I/O can be transmitted and received via individual memory-
mapped registers, or the data can be autobuffered directly into the
processor’s data memory. This autobuffering is similar to serial port
autobuffering, as described in Chapter 5.
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