I2S sound with PCM5122 / DigiAMP+

[Klaus42]

Hello to everybody,

 

I am using rock 5b, PCB Version 1.42 with Armbian 22.11 CLI.

 

I would like to  connect IQaudIO DigiAMP+ based on the TAS5756 (https://shop.max2play.com/en/iqaudio-digiamp.html). According to the GPIO pinout of ROCK 5b and the datasheet of DigiAMP+ (page 21), this seams to be feasible from the electrical perspective.

But the software perspective overwhelmes me as a linux novice.

 

If I understand it correctly, I need more or less two things:

1. a device tree overlay to activate the appropriate GPIOs with their I2S and I2C functionality and to tell the kernel about the attached device (DTS file or the compiled DTO file)
2. an appropriate driver (kernel module) for the device

 

I have not found any useful examples about how to write device tree overlay files for the rock 5 with I2S support.

Does anybody out there have a generic I2S example for rock5b or maybe even a working device tree file for the the DigiAMP+?

 

According to  https://dev.seemoo.tu-darmstadt.de/bcm/bcm-rpi3/-/blob/master/kernel/arch/arm/boot/dts/overlays/iqaudio-dacplus-overlay.dts, the TAS5756 is compatible with the PCM5122. But according to the file /boot/config-5.10.110-rockchip-rk3588, line 5168 (content is # "CONFIG_SND_SOC_PCM512x_I2C is not set"), the standard armbian kernel is not compiled with support for this chip. Is this assumption correct?

 

Thank you in advance!

 

Regards, Klaus

Edited January 11, 2023 by Klaus42

[Igor]

6 hours ago, Klaus42 said:

standard armbian kernel is not compiled with support for this chip

At least this part is relatively easy - generate a PR in similar fashion: https://github.com/armbian/build/pull/4611 

[Klaus42]

Hi Igor,

 

thank you for pointing me to that URL. I was able to build the kernel with

• in ~: call 

  sudo ./compile.sh BUILD_ONLY=kernel BOARD=rock-5b KERNEL-CONFIGURE=yes

   

• In kernel configuration: But an asterisk in front of Device Drivers->Sound Card Support-->Advanced Linux Sound Architecture-->ALSA for SoC audio support -->CODEC drivers-->Texas Instruments PCM512x CODECs - I2C  (it took ages to find this path...)
• Save and Exit
• Wait until the kernel has been compiled
• in ~/build/output/debs: call 

  sudo dpkg -i linux-image-legacy-rockchip-rk3588_23.02.0-trunk_arm64.deb

Hopefully, somebody is able to help me with the I2S overlay stuff...

 

Regards,

 

Klaus

[Klaus42]

Is anybody out there who can help help me to tackle this challenge? I do not want to go back to Raspberry Pi and Rasbian OS... 

 

Regards, Klaus

[le51]

Hey Klaus,

 

I own an IQaudio Dac Pro and I want it to run on Rock5b.

I'm a bit busy these days for investigating right now, but here are some points:

 

• IQaudio boards have an ASoc driver like:

https://github.com/raspberrypi/linux/blob/rpi-5.15.y/sound/soc/bcm/iqaudio-dac.c

or

https://github.com/raspberrypi/linux/blob/rpi-5.15.y/sound/soc/bcm/iqaudio-codec.c

 

Maybe they need some tweaks

• You have to write and compile a device tree overlay like this one

https://github.com/raspberrypi/linux/blob/rpi-5.15.y/arch/arm/boot/dts/overlays/iqaudio-dacplus-overlay.dts

 

• I've seen on radxa repository that there is already a dts file for an Audioinjector board:

https://github.com/radxa/overlays/blob/main/arch/arm64/boot/dts/rockchip/overlays/audioinjector-isolated-soundcard.dts

but this shouldn't be for the rock5b, as GPIO pinout (https://wiki.radxa.com/Rock5/hardware/5b/gpio) list I2S2 and I2C7 as the right data lanes name.

 

• Be sure that I2C7 and I2S2 are in "okay" status (haven't checked) in the device tree

Hope this helps, and keep us in touch 😉

 

Good luck

[Klaus42]

Hi le51,

 

sorry for the severely delayed answer. Doing all this is far beyond my knowledge and my time budget. I think, going back to RasPi is the best alternative...

 

However, thank you for your help!

 

Regards