Lpc2000

Yes. When /ws is 1 no data will be transmitted from SPI as slave. In 
the case of I2S you will want the duty cycle of /ws to be 50% and the 
period 2x the number of data bits. 


Ian



--- In lpc2000@yahoogroups.com, "ee_gary" <ee_gary@...> wrote:
>
> Is it safe to assume that mono audio can be generated by using only
> one SPI port?
> 
> Gary
> 
> --- In lpc2000@yahoogroups.com, "ian.scanlon" <scanlon.design@> 
wrote:
> >
> > ** oops **  Misread the docs on /WS (word select).  But the 
concept 
> > is still the same with two slaves and externally generated /ws 
and 
> > clock.  Very simple if you can use both SPI ports.
> > 
> > 
> > --- In lpc2000@yahoogroups.com, "ian.scanlon" <scanlon.design@> 
> > wrote:
> > >
> > > I have done something similar.  I2S from uC to DAC looks like 
> > (quick 
> > > review) simple SPI interface.
> > > 
> > > You need to create a system with two slave devices and an 
external 
> > > source for clock and /select. Set SPI port slave, DAC already 
slave.
> > > 
> > > Data:  Connect directly- uC slave out to DAC in
> > > Clock: External clock source (timer output ?) connects to both 
uC 
> > and 
> > > DAC. Used to clock the data from the SPI port to the DAC.
> > > /select: Use timer fed by clock(above) with period set to 
sample 
> > > output rate and pulse width-low to count the number of bits in 
each 
> > > sample.  
> > > 
> > > Now you just need to keep the SPI buffer full - either 
interrupt or 
> > > polled.  The data is transfer from the SPI port (as slave) to 
the 
> > DAC 
> > > clocked by the clock and /select you have supplied.
> > > 
> > > Philips has a document "I2S Bus Specification" that may be 
> > helpful,  
> > > don't know the real .pdf filename.
> > > 
> > > 
> > > Ian
> > > 
> > > --- In lpc2000@yahoogroups.com, "ee_gary" <ee_gary@> wrote:
> > > >
> > > > I'm interested in this as well.  Has anyone successfully 
> > > communicated
> > > > with an I2S DAC using SPI?
> > > > 
> > > > Gary
> > > > 
> > > > --- In lpc2000@yahoogroups.com, "croquettegnu" 
<croquettegnu@> 
> > > wrote:
> > > > >
> > > > > Thanks but this link concerns at91 product !
> > > > > you mean there are no peripherals dedicated to I2S or AC97 
in 
> > the
> > > > LPC ???
> > > > > 
> > > > > Thanks
> > > > > --- In lpc2000@yahoogroups.com, "ian.scanlon" 
<scanlon.design@> 
> > > wrote:
> > > > > >
> > > > > > See:
> > > > > > 
http://www.atmel.com/dyn/resources/prod_documents/doc2646.pdf
> > > > > > 
> > > > > > to implement in CPLD.
> > > > > > 
> > > > > > You can also set the SSP as slave and use internal timers 
and 
> > > some 
> > > > > > external logic to generate required signals and timing.
> > > > > > 
> > > > > > Ian
> > > > > > 
> > > > > > 
> > > > > > --- In lpc2000@yahoogroups.com, "croquettegnu" 
> > <croquettegnu@> 
> > > wrote:
> > > > > > >
> > > > > > > I need to use the I2S protocol and I am looking for 
what 
> > would
> > > > be the
> > > > > > > most appropriate peripheral to deal with ???
> > > > > > > 
> > > > > > > Is AC97 possible too ?
> > > > > > > 
> > > > > > > Thanks a lot !
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>