Lpc2000

To interface to MMC or SD card is very easy and if you use SPI than very
little of processor power is
needed. I2S can be done with CPLD
<http://www.atmel.com/dyn/resources/prod_documents/doc2646.pdf>
http://www.atmel.com/dyn/resources/prod_documents/doc2646.pdf , but
maybe there is a simpler method.
Janek 

-----Original Message-----
From: Robert Buadu [mailto:robu@...] 
Sent: Wednesday, February 11, 2004 22:03
To: lpc2100@yahoogroups.com
Subject: Re: [lpc2100] Audio DAC


The LPC2106 is powerfull enough to decode mp3. The Helix mp3 code runs 
at 30MHz on the arm7 core, so there is a lot processing power to spare.

If one can find a neat way to drive an Audio DAC and read from say a MMC

card with the remaining power, you have a nice little mp3 player using a

minimum number of components.

So I guess we are just trying to be minimalistic. Finding neat solutions

to problems. Just for the fun of it.

/RB

Alaric B Snell wrote:

> Robert Buadu wrote:
> 
> 
>>One can do away with interrupts and code counting the cycle time of
the 
>>instructions. With this you will more or less have a dedicated
parallell 
>>to I2S converter. One probably can't do very much more with the
processor.
>>
>>A few audio DAC's have a block mode, which does not need a precise 
>>clock. This allows you to bit-bang the interface. In this case it is 
>>quite feasible. You only need an interrupt every sample, that is every

>>1280 cycles. You then send out a stream of data with the minimum
allowed 
>>clock cycle for block mode. Now, I've not actually tried this so it 
>>might not work. There was very little info about this mode in the 
>>datasheet I was reading.
> 
> 
> I'm looking at the MAS3587F MP3 codec. You control it with I2C, then 
> feed data in and out via an 8-bit parallel interface with 5 control 
> bits. I'm thinking that would be quite easy; MP3 data rates are in the

> realms of 128KBit/sec (16KBytes/sec). I can manage to output a byte
via 
> GPIO every 16,000ths of a second, no problems :-)
> 
> There's also the STA013 which, at a pinch, can apparently be fed its
MP3 
> stream via SPI, but that's a decoder only. Which is probably fine for 
> you. Unlike the MAS3587F, though, it generates a serial audio signal 
> which needs to be fed into a DAC.
> 
> http://www.open-research.org.uk/ARMuC/index.cgi?STA013
> 
> Of course, this is no use to you if your source data just inexorably
is 
> in uncompressed form... If so, have you considered just combining a
RAM 
> or ROM or whatever your original data source is with the DAC via some 
> glue logic in a PLD on its own clock? Perhaps you could make an audio 
> buffer device with some RAM, that exposed an SPI interface to the 
> LPC21xx for loading up in big chunks?
> 
> 
>>/RB
>>
> 
> 
> ABS
> 
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 


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