I2S Slave Mode: DragonBoard 410c (Win 10)


#1

Hi,

We’re trying to track down a board that can run in I2S Slave mode, by providing an external MCLK. Does the DragonBoard 410c operate in “slave mode”? Is there a “driver” for I2S out available in the Win10 implementation?

THanks


#2

Hi kdubious,

We only could guide you to the Windows 10 forums regarding Windows 10 topics.

Please refer the link on this thread.
https://www.96boards.org/forums/topic/windows-10/


#3

What if we ignore the Win10 part… We’re trying to track down a board that can run in I2S Slave mode, by providing an external MCLK. Does the DragonBoard 410c operate in “slave mode”? Is there a “driver” for I2S out?


#4

Hi kdubious,

I read the hardware documentation and it does not mention about slave mode of I2C bus on SpanDragon 410.
I have sent a query internally but have not heard back yet.
I have to assume I2C bus on the DragonBoard 410c could operate only host mode.

I will update you if I hear any update.


#5

HDMI audio is an example on I2S out which is connected to external HDMI PHY. In this case the MCLK is driven by the SOC. There is already driver in the mainline at https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/sound/soc/qcom?id=refs/tags/v4.4 for I2S.

AFAIK I2S slave configuration, It should be possible to do it and slave should take care of WS and MCLK lines. This configuration needs additional software setup which is missing atleast in debian linux kernel release.

TBH, unless we have strong use-case, we have no plans immediately to add this support in atleast debian released kernels


#6

Use case for i2s slave mode operation;

Ability to interface with an audio system that can function independently of the host board, for instance;

Si4743 (slave) + CS4360 (slave) + PCM1862 (master)

PCM1862 is a multi-channel (8 channel, 4xstereo) ADC + digital MUX.
Si4743 is an AM/FM/RDS receiver with analog and digital (i2s) output.
CS4360 is a multi-channel (6 channel, 3xstereo) DAC with independent volume controls (i.e. duplicate stereo signal across three pairs FL, FR, RL, RR, center, sub).
*all controlled via i2c.

Put that all together, and you have something that can be set for AM/FM playback while the host board is OFF, but only if you can keep those i2s lines operational. But more than that, the PCM1862 obviously needs to receive i2s from the SBC, and could even transmit TO the SBC. I.e., microphone attached to the PCM1862 sending audio back to SBC for recording/call/etc.