AudioOutputI2SOct

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M4ngu

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Hello, I have a question about using i2s_oct,
is this for a i2s IC (audio codec or DAC) with 8 channels or it could work with 4 stereo i2s ICs, sharing the LRCLK, MCLK and BCLK and using one TX for each one?
if the second option is possible, is there any requirement about sharing those signals with several ICs?
thanks in advance
 
could work with 4 stereo i2s ICs, sharing the LRCLK, MCLK and BCLK and using one TX for each one?

Yes, sending to 4 separate chips should work fine.

If using codec chips, keep in mind the pins are shared. You can use 8 channel input and output together, because they conflict in pin usage. Details of the pins needed are in the design tool documentation.


is there any requirement about sharing those signals with several ICs?

If the wires are not long, you should be able to just connect all 4 chips directly. You would only need to add impedance matching resistors or special buffers if the wires are excessively long. Under a few inches should be fine.

Keeping the GND wire(s) physically close to BCLK & MCLK and the other signals helps.
 
Is it possible somehow to use four audio boards with the SGTL5000 chip to get eight channel output? I cannot find any information about this.

Quad channel is working fine, btw. Really nice!!
 
Is it possible somehow to use four audio boards with the SGTL5000 chip to get eight channel output? I cannot find any information about this.

Quad channel is working fine, btw. Really nice!!

would be easier with 8channel DAC board
 
Using the audio library we have today, the main problem is the SGTL5000 control only supports using Wire (pins 18 & 19), but not Wire1 or Wire2. So while you could do the I2S audio data side by just connecting the wires as needed, to control the 3rd & 4th audio shields you would need to hack the library somewhat to make an alternate way to control those other 2 boards.

Also keep in mind you only get 5 I2S data pins, not 8. So you can use 4 of them to transmit 4 stereo streams, but you can simultaneously receive only 1 stereo stream. With I2S, each data pin is always stereo (or 2 independent channels if you like).
 
Using the audio library we have today, the main problem is the SGTL5000 control only supports using Wire (pins 18 & 19), but not Wire1 or Wire2. So while you could do the I2S audio data side by just connecting the wires as needed, to control the 3rd & 4th audio shields you would need to hack the library somewhat to make an alternate way to control those other 2 boards.

Also keep in mind you only get 5 I2S data pins, not 8. So you can use 4 of them to transmit 4 stereo streams, but you can simultaneously receive only 1 stereo stream. With I2S, each data pin is always stereo (or 2 independent channels if you like).

Thanks for the quick reply. I would need only output channels. It sounds that this would be possible channel wise. Not sure if I would be able to hack the library accordingly.

Do I understand it right that other chips than the SGTL5000 would be supported directly? Do you have any recommendations or are there boards available? I will look into that.

Would be nice to have 6 or 8 output channels. I am building small mobile musical instruments with integrated loudspeakers. Experimenting with the acoustic sound field with more channels in such a small device would be really great.
 
Trying to understand the current status of available options I see:

There is no available "off the shelve" option to make use of AudioOutputI2SHex or AudioOutputI2SOct from the audio library (to use it with SGTL5000 audio boards it would be necessary to hack the audio library).

Designs for test boards for TDM output using ADAU1966A or cs42448 chips are available for 6 or 8 (or even more) output channels.
This would mean I would have to order a PCB and complete it with chips on my own.

I was hoping there is something as easy to use as the audio boards for more than 4 channels. Not sure if I will follow that paths because I am trying out ideas only at the moment. I would like to put more time in the sound design part. Building the hardware is some effort for me personally.
Probably the best for me to run tests with 6 channel audio output on my devices without Teensy first to decide later how much effort I would like to put into this.
 
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