AN1836-AN21161 Analog Devices, AN1836-AN21161 Datasheet - Page 2

• Manufacturer Part Number: AN1836-AN21161
• Description: Interfacing the ADSP-21161 SIMD SHARC DSP to the AD1836 (24-bit/96 kHz) Multichannel Codec
• Manufacturer: Analog Devices

Figure 1. 24-bit/96kHz AD1836 Multichannel Audio Codec
0. Introduction
This application note describes how to interface the ADSP-21161 to the AD1836 for use in professional, consumer, or
automotive audio systems. Using the AD1836 gives the DSP audio system designer more flexibility for capture and playback
of "professional-quality" 24-bit audio by providing the capability of processing multiple high-fidelity digital audio signals
simultaneously.
The AD1836 Multichannel 24-bit 96kHz Codec is a high-performance, single-chip 5 Volt stereo Codec system providing three
stereo DACs and two stereo ADC’s using patented Sigma-delta conversion techniques. The ADCs and DACs are capable of
maintaining 105 dB SNR and Dynamic Range. With extended serial port TDM and auxiliary I/O features, the AD1836 can
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also interfaced to additional external audio I2S devices, providing a "backdoor" path to the TDM bus for 3 external I
S devices,
to allow 8-channel I/O. The ability to utilize 8 input/output channels of audio enables the use of the AD1836 in a wide variety
of professional and consumer audio applications requiring multiple I/O, such as: digital mixers, effects processors, home
recording studios, DVD players, home theatre systems and automotive audio systems. No additional hardware glue-logic is
required for the simple TDM interface mode, and the programming of the AD1836 modes of operation is easily accomplished
through DSP software programming. Please note that this application note will only describe the AD1836's TDM interface, and
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not the other modes of operation (I
S, packed mode, etc).
The ADSP-21161 SIMD SHARC DSP offers 2 identical computation unit sets (2 register files, 2 ALUs, 2 MACs, 2 barrel
shifters), providing the ability to process multiple 24-bit audio streams concurrently with the use of SIMD. The two
computation units can process audio streams with either 32-bit fixed point, 32-bit IEEE floating point, or 40-bit extended
precision floating point processing. Thus, the ability to maintain the integrity of the 24-bit/105 dB signal quality is achievable
through 32-bit audio processing without resorting to double precision arithmetic, and a 2x performance increase for many
standard DSP algorithms, such as FIRs, IIRs, and FFTs.
AD1836 assembly and C driver source code examples are provided in the application note for reference purposes. This source
code was tested and verified using the ADDS-21161N EZ-KIT Lite Development Platform, which includes an AD1836,
AD1852 and SP/DIF receiver as the analog/digital audio interface.
I would like to also thank Dan Ledger of Analog Devices for his contribution of the AD1836 C-based Driver Source Code!