1. Are you using DSP BIOS? If so the DSP Bios might have changed the
speed through the Bios tool
2. How are you increasing the size of the lookup table? Are you just
recopying the first 256 bytes over and over? Or are you spreading it out
among the new larger tables?
Carl Chipman
Nomadics, Inc.
http://www.nomadics.com
-----Original Message-----
From: sahana rao [mailto:]
Sent: Wednesday, May 15, 2002 4:14 AM
To:
Subject: [c54x] Regarding codec
Hello
I am trying to work on CODEC.
1. when i tried to run the eg program of codec given
by the TI it ran successfuly and i checked out that i
am getting a sine wave on pin 23 of TLC320AD50 chip.
when i halted the program the CLKMD changes to 4007
which is 100MHZ which should be 1007 i.e 40MHZ because
my DIP switches 5 & 6 are up.
2. when i increase the number of points in lookup
table(in the eg program the lookup table is 256) like
512,1024,2048,4096 the amplitude of the sine wave goes
on decreasing and the period of the sine wave also
increases can anyone tell me why?
thanks
_____________________________________
Note: If you do a simple "reply" with your email client, only the
author
of this message will receive your answer. You need to do a "reply
all"
if you want your answer to be distributed to the entire group.
_____________________________________
About this discussion group:
>2. when i increase the number of points in lookup >table(in the eg program the lookup table is 256)
like
>512,1024,2048,4096 the amplitude of the sine wave goes
>on decreasing and the period of the sine wave also
>increases can anyone tell me why?
When you increase the size of the table the period of the wave increases ie
the frequency of the wave decreases as the sampling rate (or the rate at
which you are reading out the data) is fixed. Meaning that doubling the
table size means it takes twice as long to output the entire waveshape
resulting in a frequency/period change. As for the change in amplitude the
only thing that comes to mind at the moment is there might be a high pass
filter in the codec thats attenuating your signal the lower you go, but
thats just a shot in the dark.
Polyhex
Reply by sahana rao●May 15, 20022002-05-15
Hello
I am trying to work on CODEC.
1. when i tried to run the eg program of codec given
by the TI it ran successfuly and i checked out that i
am getting a sine wave on pin 23 of TLC320AD50 chip.
when i halted the program the CLKMD changes to 4007
which is 100MHZ which should be 1007 i.e 40MHZ because
my DIP switches 5 & 6 are up.
2. when i increase the number of points in lookup
table(in the eg program the lookup table is 256) like
512,1024,2048,4096 the amplitude of the sine wave goes
on decreasing and the period of the sine wave also
increases can anyone tell me why?