add devicetree overlay for i2s and asound.conf

.gitignore

@@ -46,3 +46,6 @@ src/auracast/server/certs/ca/ca_cert.srl
 src/auracast/server/credentials.json
 pcm1862-i2s.dtbo
 test.wav
+both.wav
+vin1.wav
+vin2.wav

src/misc/asound.conf

@@ -0,0 +1,39 @@
+# --- raw HW by card ID (no sharing) ---
+pcm.adc_hw_stereo {
+  type hw
+  card "i2s"   # from `arecord -l`: card 2: i2s [pcm1862 on i2s]
+  device 0
+}
+
+# --- mono splits (do the routing here) ---
+pcm.adc_in1 {
+  type route
+  slave.pcm "adc_hw_stereo"
+  slave.channels 2
+  ttable.0.0 1.0   # left -> mono
+  ttable.1.0 0.0
+}
+
+pcm.adc_in2 {
+  type route
+  slave.pcm "adc_hw_stereo"
+  slave.channels 2
+  ttable.0.0 0.0
+  ttable.1.0 1.0   # right -> mono
+}
+
+# --- diagnostics: exact slot taps (bypass any sharing/conversion) ---
+pcm.adc_ch0 {
+  type route
+  slave.pcm "adc_hw_stereo"
+  slave.channels 2
+  ttable.0.0 1.0
+  ttable.1.0 0.0
+}
+pcm.adc_ch1 {
+  type route
+  slave.pcm "adc_hw_stereo"
+  slave.channels 2
+  ttable.0.0 0.0
+  ttable.1.0 1.0
+}

src/misc/install_asoundconf.sh

@@ -0,0 +1 @@
+sudo cp src/misc/asound.conf /etc/asound.conf

src/misc/pcm1862-i2s.dts

@@ -7,24 +7,28 @@
     /* Enable the I²S controller */
     fragment@0 {
         target = <&i2s>;
-        __overlay__ { status = "okay"; };
+        __overlay__ {
+            status = "okay";
+        };
     };
 
-    /* PCM1862 on I2C1 at 0x4a */
+    /* PCM1862 on I2C1 at 0x4a (change if your bus/address differ) */
     fragment@1 {
         target = <&i2c1>;
         __overlay__ {
             #address-cells = <1>;
             #size-cells = <0>;
+
             pcm1862: adc@4a {
                 compatible = "ti,pcm1862";
                 reg = <0x4a>;
                 #sound-dai-cells = <0>;
+                /* Rails are hard-powered on your board, so no regulators here */
             };
         };
     };
 
-    /* Link bcm2835-i2s <-> pcm1862 with simple-audio-card */
+    /* Link bcm2835-i2s <-> pcm1862 via simple-audio-card */
     fragment@2 {
         target-path = "/";
         __overlay__ {