I2S input


#1

Is it possible to get I2S input on the DragonBoard 410C?
I’ve seen several people bring it up in this forum and little example of success.

I’d like to use a I2S digital audio device as a sound source into the DragonBoard and I can do this with the Intel Edison but I haven’t found a good solution for the DragonBoard.


#2

I am also interested to learn how a I2S input (for an audio AD converter in my case) can be added.

Peter


#3

Hi Guys,

After looking over the specs I think there might be an I2S input present on the low speed header, specifically pins 16, 18, 20. These pins correspond, respectively, to WS, SCK, and DATA0 for I2C. I am attaching the schematic for the low speed header with the I2S inputs boxed in green showing the signals going to GPIOs 110, 113, and 114.

Also, it looks like Qualcomm states that I2S is available via the low speed header on their Dragonboard 410c page. https://developer.qualcomm.com/hardware/dragonboard-410c

~Nick


#4

https://www.96boards.org/forums/topic/dragonboard-410c-audio-jack/

According to the last post from a Qualcomm employee I2S input is not possible from that port.
Can anyone confirm that?


#5

Link for my last post just in case.


#6

The post I am referring to:

"3) The I2S is output only. When the pins are not being used for I2S they can be configured as GPIOs. When configured as GPIO they can be inputs.

I am not sure how the SW is configured, you may need to make changes to the OS to enable multiple microphones.

Full Disclosure: I am an employee of Qualcomm Canada, any opinions I may have expressed on any post are my own and do not reflect the opinions of my employer."

Just in case this displays differently in different browsers.


#7

I can guarantee you with absolute certainty, that the HARDWARE is definitely capable.
The issue is that the software has not been written for it.
It will require some changes in the kernel, both to the pin configurations, as well as to the audio driver.

Not only that, but you could actually do two stereo pairs of inputs, outputs, or one of each.

On the low speed header;
16: WS
18: CLK
20: Data0
27: Data1. Note that this pin has been repurposed as “GPIO-E”, but it is still connected.

If you refer to the register documentation around page 3058/3059, it refers to the direction that the i2s lines are configured for. 0: SPK direction – output, 1: MIC direction – input, 2: BIDIRECTIONAL!!!