I2S - PCM5102 - Orange pi lite (H3)

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superbert
Posts: 2
Joined: Fri Feb 16, 2018 11:20 am

I2S - PCM5102 - Orange pi lite (H3)

Post by superbert »

Hi all,

First of all, thanks for the tremendous effort in building the dietpi images!

I'm trying to get my head around a difficult issue...but the learning curve is a bit steep for me (as a linux noob), so many questions...few answers up to now :-(

I want to connect an external DAC (PCM5102) to my Orange-Pi Lite via I2S (The USB DAC works, but I'm not satisfied with the quality). Since the newer kernels no longer support the "fex" concept, I have to use to device-tree overlays...there's no ready made device-tree overlay available for the H3.

So, can I just copy an existing DT-overlay from another board to /boot/overlay_user and modify the pin specifications?

I2S Example I found for the sun7i:

Code: Select all

/dts-v1/;
/plugin/;

/ {
	compatible = "allwinner,sun7i-a20";

	fragment@0 {
		target = <&pio>;
		__overlay__ {
			i2s0_pins: i2s0 {
				pins = "PB5", "PB6", "PB7", "PB8", "PB9", "PB10", "PB11", "PB12";
				function = "i2s0";
			};
		};
	};

	fragment@1 {
		target = <&i2s0>;
		__overlay__ {
			pinctrl-names = "default";
			pinctrl-0 = <&i2s0_pins>;
			status = "okay";
		};
	};
};
H3 OrangePi Lite pin-out would be:
- PA18, PA19, PA20, PA21 (LRCK, BCLK, DO, DI)

Would it just be a matter of changing the file, running "armbian-add-overlay" and magically it works? It's probably not this simple...
What about defining the DAC (pcm5102)? Isn't that needed at all in the overlay file?

Up to now I wasn't able to find/get the "armbian-add-overlay" tool, any hints?

I found another overlay example on the another forum, but this one doesn't contain pin-definitions at all....how could this ever work? This one does however contain the definition for the DAC (I'm puzzled).

Code: Select all

/dts-v1/;
/plugin/;

/ {
	compatible = "allwinner,sun8i-h3";

 	fragment@0 { 
 		target-path = "/"; 
 		__overlay__ { 
			pcm5102a: pcm5102a {
			#sound-dai-cells = <0>;
			compatible = "ti,pcm5102a";
			pcm510x,format = "i2s";
			};
 		}; 
 	}; 

	fragment@1 {
		target = <&i2s0>;
		__overlay__ {
			status = "okay";
			pinctrl-0 = <&i2s0_pins>;
			sound-dai = <&pcm5102a>;
			pinctrl-names = "default";
		};
	};

	fragment@2 {
		target-path = "/";
		__overlay__ {
			sound_i2s {
				compatible = "simple-audio-card";
				simple-audio-card,name = "I2S-master";
				simple-audio-card,mclk-fs = <256>;
				simple-audio-card,format = "i2s";
		                status = "okay";

				simple-audio-card,cpu {
					sound-dai = <&i2s0>;
				};

				simple-audio-card,codec {
					sound-dai = <&pcm5102a>;
				};
			};
		};
	};
};
My gut feeling says that I need to define the bus (I2S) including pins to be used, and the DAC to be used over that bus.

Thanks for any help / hints to get me up the learning curve...

Best regards,

Eeg.
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