Lpc2000

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
>>
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> ABS
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