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Engineer-to-Engineer Note EE-243
Technical notes on using Analog Devices DSPs, processors and development tools
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Using the Expert DAI for SHARC® Processors
Contributed by Mitesh Moonat, Je y anthi J egade e san, J agadee sh Ray ala, and Srini v as K Rev 7 – June 28, 2010
Introduction
This EE-Note explains how you use the VisualDSP++® Expert DAI plug-in to co nfigure the signal routing
unit (SRU) in ADSP-2126x, ADSP-2136x, ADSP-2137x, and ADSP-214xx SHARC® processors. The
Expert DAI plug-in simplif ies th e task of genera tin g the C and/or assembly code that is used to progr am the
SRU. The Expert DAI plug-in asso ciated with this EE-Note can be used with the VisualDSP++ 3.5, 4.0,
4.5 and 5.0 versions.
Digital Audio Interface and SRU
The digital audio interface (DAI) in ADSP-2126x, ADSP -2136x, ADSP-2137x, and ADSP-214xx SHARC
processors comprises a group of peripherals and the SRU. The peripheral's inputs and the outputs do not
connect to the 20 exter nal DAI pins (DAI_P20-1) directly. Instead, t he SRU establishes these connections,
based on a set of configuration registers. This feature allows you to interconnect t he peripherals to suit a
wide variety of systems. It also allows including an arbitrary number and variety of peripherals while
retain ing h igh levels of c ompatib ility without increasing pin count.
The S RU in all the above processor families contains at least six groups of registers (named A through F).
ADSP-2147x family of processors contain an additional group, named group G, to support ro ut ing of shift
regi st er sign als. Each group ro utes a unique set of signals with a specific purpose. For example, group A
rout es clock signals, gro up B routes frame sync signals, and group C rout es serial data signals. Toget her,
the SRU’s gro ups include all of the DAI peripherals' inputs and outputs, additional signals from the core,
and all the connections to the DAI pins. For additional information on the DAI and SRU, refer to the
processor's Hardware Reference Manual
[1] [2] [3] [4]
.
Programming the SRU requires an in-depth understanding of the SRU registers, bit field positions
correspo nding to different destination signals in all the registers, the number of bits allocated for each bit
field in all the registers, and the values that correspo nd to different source signals in all of the registers.
VisualDSP++ tools include a macro for programming the SRU r egister s. T his macro requires that you have
background knowledge about all of the SRU signals and registers. The Expert DAI plug-in, however,
provides an easy method of generating the code necessary to configure t he SRU registers. The Expert DAI
graphical user interface allows you to generat e the code without having to wor r y about the internal details.
Note that, in addition to S RU and DAI , the AD SP -21367, ADSP-21368, ADSP-21369, ADSP-2137x, and
ADSP-214xx processors have a secondary Signal Routing Unit (SRU2) and 14 pins, which are available on
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