loopback application

7/21/2019 LoopBack Application

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Loop Back (or Pass Through) Application

The loop back or pass through application consists of sending an audio lefrom a PC to the C6713 DSP via the analogue to digital converter Codec!

and then getting it back through the digital to analogue converter Codec!"T#o peripherals of the C6713 DSP are used for this purpose$ the %ultichannel&u'ered Serial Port %C&SP! and the (nhanced Direct %emor) *ccess" Thisapplication #ill be used as the basis for implementing a three band e+uali,er"

The implementation #ill be embedded bet#een the receive side of the (D%*g&u'er-cv! and the transmit side of the (D%* g&u'er.mt!/ usinghard#are events"

Figure 1:Pass through application

Enhanced Direct Memor Access (EDMA)

The (D%* is a peripheral that can be set up to cop) data from one locationto another !ithoutCP0s intervention" The (D%* can be set up to cop) dataor a programme from a source e2ternalinternal memor)/ or serial port! to adestination e"g" internal memor)!" *fter this transfer completes/ the (D%*can 4auto5initialise itself and perform the same transfer again/ or it can bereprogrammed" n the case of C6713 DSP/ it includes 16 channels and is ableof storing parameters for 68 reload entries for reprogramming the (D%*!"

Multichannel Bu"ered #erial Port (M$B#P)

%ultichannel bu'ered serial ports provide an interface to ine2pensiveindustr) standard! e2ternal peripherals" The) have features such as fullduple2 communication/ independent clocking and framing for receiving andtransmitting/ and direct interface to *C87 compliant device" t allo#s severaldata si,es bet#een 9 and 3: bits"

$%DE$

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The available codec on the DS; 6713 board is the T*C:3 *C:3! 165

bit stereo coderdecoder C?D(C! device" The C?D(C interfaces to the 6713

DSP via the %C&SP serial interface"

#tarting a ne! pro&ect


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Eour pro@ect e2plorer should look something like the one in gure 3" %ake

sure to delete C6713"cmd if it has been automaticall) added to the pro@ect"

Figure 2:Pro@ect (2plorer

Adding Files to the Pro&ect

Do#nload the


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main"c

edma"c

codec"c

sine"c

mcbsp"c

*t the end of this process/ the pro@ect e2plorer should look like the one of

gure F"

Figure ;:Pro@ect (2plorer after *dding the iles

Target $on


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Figure =: Target $onindo!

$reating a D#P?B@%# $on


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Figure +:DSP&?S Conguration

Then click on ne2t and select ti"platforms"dsk6713 as illustrated in gure 7!/

#hich corresponds to the Dsk6713 ::B %h,!" Click on 4inish to complete

the process"

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Figure .:DSP&?S Conguration G Platforms

n this application/ a single feature of the DSP&?S #ill be used" ?nl) oneob@ect #ill be set up" t consists of linking the (D%* interrupt to itscorresponding interrupt service routine S-!"

Adding the >@ to our #stem

Ho# does the CP0 kno# #hat to do #hen the interrupt occursI here doese2ecution goI e need to tell the CP0 that #hen the (D%* interrupt occurs/to run the interrupt service routine S-!/ edmaH#i!" The follo#ing steps #illaccomplish this"

?pen the TC le and click the Jsign ne2t to scheduling/ then click the Jsignne2t to H gure 9!" * list of hard#are interrupts #ill appear" Hard#areinterrupt K9 HLMT9! is the (D%* interrupt to the CP0 b) default!" -ightclick HLMT9 and select Properties" Change the function name to

LedmaH#i gure 8!" The hard#are interrupt vector table is #ritten inassembl)/ so the underscore is re+uired to access the C function/ edmaH#i!"

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Figure :nterrupt Conguration

Figure C: nterrupt properties G nterrupt Source

6se the dispatcher7 Click on the dispatcher tab and check UseDispatcher checkbo2" The hard#are interrupt dispatcher #ill do somehousekeeping for us b) savingrestoring the conte2t #hen processing the

S-" Close and Save"

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Figure C: nterrupt properties G Dispatcher

$hip #upport Li5rarThe Chip Support


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director) CAOProgram ilesOC62CS>> Compiler ?ption

Figure 11:*dd Director) indo# G CS< header les

e #ill take the opportunit) to add some other header les that re+uired b)

the pro@ect" The path represents a #orking director)" n gure 1:/ it ispointing to m) #orking director)"

Page 1>


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Figure 1:*dd Director) indo# G ?ther header les

hen the process is completed/ the 4Pro@ect Properties#indo# should look

like the one of gure 13"

Figure 12:Pro@ect Properties after %odications

CS< #ill also need to kno# #hat DSP platform is to be used" This can be

specied in the Pro&ect Properties #indo# gure 1>! b) selecting

4Prede>


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Figure 1;:Pro@ect Properties G C6>>>

loopback application

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