feat: configure PCM1862 differential inputs and optimize audio buffer settings

- Added PCM1862 I2S interface setup with differential input configuration via I2C
- Reduced audio buffer latency by decreasing period_size from 240 to 120 samples (5ms to 2.5ms)
- Updated buffer_size to 360 samples for both channels to maintain stable audio capture

README.md

@@ -218,6 +218,18 @@ sudo ldconfig                        # refresh linker cache
 	- echo i2c-dev     | sudo tee -a /etc/modules
 - read temp /src/scripts/temp 
 
+# configure the pcm1862 i2s interface
+bash misc/build_pcm1862_dts.sh
+bash misc/install_asoundconf.sh
+
+- configure differential inputs
+sudo modprobe i2c-dev
+i2cdetect -y 1 | grep -i 4a || true
+
+i2cset -f -y 1 0x4a 0x00 0x00   # Page 0
+i2cset -f -y 1 0x4a 0x06 0x10   # Left = VIN1P/M [DIFF]
+i2cset -f -y 1 0x4a 0x07 0x10   # Right = VIN2P/M [DIFF]
+
 # test recording
  arecord -f cd -c 1 -D record_left left.wav -r48000
  arecord -f cd -c 1 -D record_right right.wav -r48000

src/misc/asound.conf

@@ -6,12 +6,13 @@ pcm.ch1 {
         channels 2
         rate 48000
         format S16_LE
-        period_size 240    # 5 ms @ 48 kHz
-        buffer_size 480    # 2 periods (≈10 ms total)
+        period_size 120    # 2.5ms
+        buffer_size 360    
     }
     bindings.0  0
 }
 
+
 pcm.ch2 {
     type dsnoop
     ipc_key 2241234
@@ -20,8 +21,8 @@ pcm.ch2 {
         channels 2
         rate 48000
         format S16_LE
-        period_size 240    # 5 ms @ 48 kHz
-        buffer_size 480    # 2 periods (≈10 ms total)
+        period_size 120
+        buffer_size 360
     }    
     bindings.0  1
 }