Re: How do I set up multiple codecs on one I2S - without TDM?

[John Watts <contact@jookia.org>]

On Thu, Jul 27, 2023 at 11:45:01AM +0200, Pierre-Louis Bossart wrote:
> On 7/26/23 12:48 AM, John Watts wrote:
> > Hello there!
> > 
> > I have an interesting problem that I'm trying to solve. It will require
> > writing adding driver support but right now I'm struggling to understand
> > how I should go about it all.
> > 
> > As a background, this is with the Allwinner D1 or T113. It has a 16
> > channel I2S controller and each channel can be configured to use a
> > specific pin and TDM time slice. Even channels are low LRCLK, odd are
> > high LRCLK.
> > 
> > So for my situation I want to have six channels:
> > 
> > - Channel 0: Timeslot 0, Pin 0, LRCLK 0 -> ADC 1
> > - Channel 1: Timeslot 0, Pin 0, LRCLK 1 -> ADC 1
> > - Channel 2: Timeslot 0, Pin 1, LRCLK 0 -> ADC 2
> > - Channel 3: Timeslot 0, Pin 1, LRCLK 1 -> ADC 2
> > - Channel 4: Timeslot 0, Pin 2, LRCLK 0 -> ADC 3
> > - Channel 5: Timeslot 0, Pin 2, LRCLK 1 -> ADC 3
> 
> It would help if you described what those different 'channels' are supposed
> to transmit. Usually channels mean a group of data that is rendered at the
> same time. It looks like you plan on transmitting independent streams that
> may be enabled/disabled separately.
> 
> Also you should describe if there are independent clocks or if all those 6
> 'channels' are transmitted with a single pair of bit/frame clocks? That
> completely changes the model, in the former case you could represent
> independent DAIs/dailinks but in the latter case you really have a single
> muxed stream.

Hello,

These channels are intended for measuring vibration at various points in a
vehicle. Each channel is a vibration measurement.

These all use the same I2S clock, multiplexing is handled by having each ADC
connected to a different I2S pin.

John.