Lpc2000

Hi,

I have a software MP3 decoder running in my LPC2106, but I'm still 
looking wor a way to interface an audio DAC. I2S seems to be impossible 
to implement without expensive additional hardware (CPLD/FPGA), and I 
didn't find any DACs with SPI, except for the VS10xx (which would be 
kind of stupid for a software MP3 decoder).

Any ideas?

Thanks
Andreas

Il giorno mer, 16-03-2005 alle 08:34 +0100, Andreas Schwarz ha scritto:
> Hi,
> 
> I have a software MP3 decoder running in my LPC2106, but I'm still 
> looking wor a way to interface an audio DAC. I2S seems to be impossible 

If you dont' need high audio quality, you can try with PWM output of
LPC2106 followed by an active low pass filter and amplifier.

-- 
FabioDB <fabiodib@...>
Altraqua

Searching google for "spi audio dac" yields some intriguing results :)
For example:

http://focus.ti.com/docs/prod/folders/print/tlv320dac26.html

On Wed, 16 Mar 2005 09:38:26 +0100, FabioDB <fabiodib@...> wrote:
>  Il giorno mer, 16-03-2005 alle 08:34 +0100, Andreas Schwarz ha scritto:
>  > Hi,
>  > 
>  > I have a software MP3 decoder running in my LPC2106, but I'm still 
>  > looking wor a way to interface an audio DAC. I2S seems to be impossible 
>  
>  If you dont' need high audio quality, you can try with PWM output of
>  LPC2106 followed by an active low pass filter and amplifier.
>  
>  -- 
>  FabioDB <fabiodib@...>
>  Altraqua
>  
>  
>  
>  
>  Yahoo! Groups Sponsor 
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-- 
Bogdan

Bogdan Marinescu wrote:
> Searching google for "spi audio dac" yields some intriguing results :)
> For example:
> 
> http://focus.ti.com/docs/prod/folders/print/tlv320dac26.html

The data interface is always I2S or something similar, SPI is only used 
as control interface.

Sorry, my mistake.

On Wed, 16 Mar 2005 11:05:00 +0100, Andreas Schwarz
<usenet@...> wrote:
>  Bogdan Marinescu wrote:
>  > Searching google for "spi audio dac" yields some intriguing results :)
>  > For example:
>  > 
>  > http://focus.ti.com/docs/prod/folders/print/tlv320dac26.html
>  
>  The data interface is always I2S or something similar, SPI is only used 
>  as control interface.
>  
>  
>  
>  Yahoo! Groups Sponsor 
>  
>  ADVERTISEMENT
>  
>  
>  ________________________________
>  Yahoo! Groups Links
>  
>  
> To visit your group on the web, go to:
> http://groups.yahoo.com/group/lpc2000/
>   
> To unsubscribe from this group, send an email to:
> lpc2000-unsubscribe@yahoogroups.com
>   
> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. 


-- 
Bogdan

--- In lpc2000@yahoogroups.com, Andreas Schwarz <usenet@a...> wrote:
> Hi,
> 
> I have a software MP3 decoder running in my LPC2106, but I'm still 
> looking wor a way to interface an audio DAC. I2S seems to be 
impossible 
> to implement without expensive additional hardware (CPLD/FPGA), and 
I 
> didn't find any DACs with SPI, except for the VS10xx (which would 
be 
> kind of stupid for a software MP3 decoder).
> 
> Any ideas?
> 
> Thanks
> Andreas

Maybe not the answer you were looking for, but the 10 bit DAC on the 
2138 does this reasonably well. The Keil development board and 
software has an MP3 and some other audio demos.

Tom

Don't forget the joys of over sampling.

The 2138 DAC has a settling time of 1 usec. You could put out data at the rate of 500Khz with over sampling and a simple finite impulse response filter this would extend the 10 bit DAC to the equivalent of 13 Bits resolution.

Some of the early cd players used to do this. They had an oversampled 14 bit DAC with FIR. The result has noticely less phase distortion than a 16 bit DAC with filters for 44Khz  

Owen Mooney 




--- In lpc2000@yahoogroups.com, Andreas Schwarz <usenet@a...> wrote:

>> Hi,
>> 
>> I have a software MP3 decoder running in my LPC2106, but I'm still 
>> looking wor a way to interface an audio DAC. I2S seems to be 
>  
>
impossible 

>> to implement without expensive additional hardware (CPLD/FPGA), and 
>  
>
I 

>> didn't find any DACs with SPI, except for the VS10xx (which would 
>  
>
be 

>> kind of stupid for a software MP3 decoder).
>> 
>> Any ideas?
>> 
>> Thanks
>> Andreas
>  
>

Maybe not the answer you were looking for, but the 10 bit DAC on the 
2138 does this reasonably well. The Keil development board and 
software has an MP3 and some other audio demos.

Tom





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