Hi,
I'm plotting the values of the iChannel0LeftIn in the sample audio codec
talkthrough but i'm receiving an erroneous output. For example, when i
input a pure sine wave using an audio generator to the audio-in of the ezkit,
the plotted figure in iChannel0LeftIn is not a sine wave. Do any of you guys
know why i'm not receiving the output of the adc properly?
I'm using...
Memory: Blackfin Memory
Address : iChannel0LeftIn
Count: 128
Stride: 1
Data: int
... for my plot configuration.
I think i should receive a sine wave because the iChannel0LeftOut has values
coming from the iRxBuffer1 who has values coming from adc ouput.
Can anyone please tell me why the output is not a sine wave? And if ever how can
i get to plot the sine wave that i am inputting to the audio-in of the ezkit?
I appreciate any repilies from you guys. Please help..
Regards
Alvin
having problems in taking output of ADC in adspbf537 ezkit lit
Started by ●February 9, 2010
Reply by ●February 9, 20102010-02-09
Howdy Alvin,
Does it kinda look like a sine wave, or does it look like random noise?
If it's more like random noise, you're loading the data from the wrong
place in memory. Find the adc input buffer and dump the hex or decimal
values. If that looks garbled, check that the signal going into the adc
from the signal generator is actually on the input pin.
You can fix the problem - but first you need to find out where the problem
really is. Binary search is really useful - does the problem happen
before or after a certain point in the process? Narrow down the region
where the problem really is, and usually the problem is trivial to fix.
Patience, persistence, truth,
Dr. mike
On Tue, 9 Feb 2010, alvin p wrote:
> Hi,
>
> I'm plotting the values of the iChannel0LeftIn in the sample audio codec talkthrough but i'm receiving an erroneous output. For example, when i input a pure sine wave using an audio generator to the audio-in of the ezkit, the plotted figure in iChannel0LeftIn is not a sine wave. Do any of you guys know why i'm not receiving the output of the adc properly?
>
> I'm using...
>
> Memory: Blackfin Memory
>
> Address : iChannel0LeftIn
>
> Count: 128
>
> Stride: 1
>
> Data: int
>
> ... for my plot configuration.
>
> I think i should receive a sine wave because the iChannel0LeftOut has values coming from the iRxBuffer1 who has values coming from adc ouput.
>
> Can anyone please tell me why the output is not a sine wave? And if ever how can i get to plot the sine wave that i am inputting to the audio-in of the ezkit?
>
> I appreciate any repilies from you guys. Please help..
>
> Regards
>
> Alvin
Does it kinda look like a sine wave, or does it look like random noise?
If it's more like random noise, you're loading the data from the wrong
place in memory. Find the adc input buffer and dump the hex or decimal
values. If that looks garbled, check that the signal going into the adc
from the signal generator is actually on the input pin.
You can fix the problem - but first you need to find out where the problem
really is. Binary search is really useful - does the problem happen
before or after a certain point in the process? Narrow down the region
where the problem really is, and usually the problem is trivial to fix.
Patience, persistence, truth,
Dr. mike
On Tue, 9 Feb 2010, alvin p wrote:
> Hi,
>
> I'm plotting the values of the iChannel0LeftIn in the sample audio codec talkthrough but i'm receiving an erroneous output. For example, when i input a pure sine wave using an audio generator to the audio-in of the ezkit, the plotted figure in iChannel0LeftIn is not a sine wave. Do any of you guys know why i'm not receiving the output of the adc properly?
>
> I'm using...
>
> Memory: Blackfin Memory
>
> Address : iChannel0LeftIn
>
> Count: 128
>
> Stride: 1
>
> Data: int
>
> ... for my plot configuration.
>
> I think i should receive a sine wave because the iChannel0LeftOut has values coming from the iRxBuffer1 who has values coming from adc ouput.
>
> Can anyone please tell me why the output is not a sine wave? And if ever how can i get to plot the sine wave that i am inputting to the audio-in of the ezkit?
>
> I appreciate any repilies from you guys. Please help..
>
> Regards
>
> Alvin
