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AD1835 / Sport ENDIAN order?? or is my code ****?

Question asked by BartW on Aug 19, 2010
Latest reply on Aug 19, 2010 by BartW


I've modified the ASM analogue in/out Talk through on an ADSP21369 EZKIT.

to do some tests.


In the sport isr for the data stream in the right channel I've effectively added the following


r10 = dm(RXSP0A);          //Read ADC Value

f0 = 0.9;                          //load f0 with scaling value
f1 = float r10;                   //convert adc value to float
f2 = f1 * f0;                         //do multiply
r12 = fix f2;                    // float to fixed
dm(TXSP2B) = r12;          //write to dac.


Now if the scaling value is <1 i get a scrachy audio signal in the right channel rather than an attenuated level.

when I multiply by 0.5 then by 2.0 i get a good signal.

When I multiply by 1 then i get a good signal.


When i watch the data in the core register watch window it looks correct.

and using a calculator i get the same but obviusly i'm doing something wrong.


Any Ideas before i pull my hair out.


Also i've not done any analog dsp assembler before is the above ok?

Many Thanks