diff --git a/README.md b/README.md
index 9073362..dd40292 100644
--- a/README.md
+++ b/README.md
@@ -41,4 +41,7 @@ https://play.google.com/store/apps/details?id=de.kai_morich.serial_bluetooth_ter
 `$ mpremote connect /dev/ttyACM0 cp ./main.py :`
 
 
-## [OpenLaserTag remote control box info](https://gitea.tomaskrejci.com/njord/lasertag_device_micropython/src/branch/master/LT_remote_control_box.md)
\ No newline at end of file
+## [OpenLaserTag remote control box info](https://gitea.tomaskrejci.com/njord/lasertag_device_micropython/src/branch/master/LT_remote_control_box.md)
+
+## Audio test
+https://learn.adafruit.com/mp3-playback-rp2040/pico-i2s-mp3
\ No newline at end of file
diff --git a/lib/audio.py b/lib/audio.py
new file mode 100644
index 0000000..9ff02eb
--- /dev/null
+++ b/lib/audio.py
@@ -0,0 +1,222 @@
+## audio.py test for audio, I2S, MAX98357
+## Tomas Krejci [Njord]
+
+## MAX98357A
+# Pico 3V3 to breakout VIN
+# Pico GND to breakout GND
+# Pico GP0 to breakout BCLK
+# Pico GP1 to breakout LRC
+# Pico GP2 to breakout DIN
+# Speaker + to screw terminal +
+# Speaker - to screw terminal -
+
+# The MIT License (MIT)
+# Copyright (c) 2022 Mike Teachman
+# https://opensource.org/licenses/MIT
+
+# Purpose:  Play a WAV audio file out of a speaker or headphones
+#
+# - read audio samples from a WAV file on SD Card
+# - write audio samples to an I2S amplifier or DAC module
+# - the WAV file will play continuously in a loop until
+#   a keyboard interrupt is detected or the board is reset
+#
+# non-blocking version
+# - the write() method is non-blocking.
+# - a callback function is called when all sample data has been written to the I2S interface
+# - a callback() method sets the callback function
+
+import os
+import time
+import micropython
+from machine import I2S
+from machine import Pin
+
+if os.uname().machine.count("PYBv1"):
+    # ======= I2S CONFIGURATION =======
+    SCK_PIN = "Y6"
+    WS_PIN = "Y5"
+    SD_PIN = "Y8"
+    I2S_ID = 2
+    BUFFER_LENGTH_IN_BYTES = 40000
+    # ======= I2S CONFIGURATION =======
+
+elif os.uname().machine.count("PYBD"):
+    import pyb
+
+    # pyb.Pin("EN_3V3").on()  # provide 3.3V on 3V3 output pin
+    # os.mount(pyb.SDCard(), "/sd")
+
+    # ======= I2S CONFIGURATION =======
+    SCK_PIN = "Y6"
+    WS_PIN = "Y5"
+    SD_PIN = "Y8"
+    I2S_ID = 2
+    BUFFER_LENGTH_IN_BYTES = 40000
+    # ======= I2S CONFIGURATION =======
+
+elif os.uname().machine.count("ESP32"):
+    # from machine import SDCard
+
+    # sd = SDCard(slot=2)  # sck=18, mosi=23, miso=19, cs=5
+    # os.mount(sd, "/sd")
+
+    # ======= I2S CONFIGURATION =======
+    SCK_PIN = 32
+    WS_PIN = 25
+    SD_PIN = 33
+    I2S_ID = 0
+    BUFFER_LENGTH_IN_BYTES = 40000
+    # ======= I2S CONFIGURATION =======
+
+elif os.uname().machine.count("Raspberry"):
+    # from sdcard import SDCard
+    # from machine import SPI
+
+    # cs = Pin(13, machine.Pin.OUT)
+    # spi = SPI(
+    #    1,
+    #    baudrate=1_000_000,  # this has no effect on spi bus speed to SD Card
+    #    polarity=0,
+    #    phase=0,
+    #    bits=8,
+    #    firstbit=machine.SPI.MSB,
+    #    sck=Pin(14),
+    #    mosi=Pin(15),
+    #    miso=Pin(12),
+    # )
+    #
+    # sd = SDCard(spi, cs)
+    # sd.init_spi(25_000_000)  # increase SPI bus speed to SD card
+    # os.mount(sd, "/sd")
+
+    # ======= I2S CONFIGURATION =======
+    SCK_PIN = 16
+    WS_PIN = 17
+    SD_PIN = 18
+    I2S_ID = 0
+    BUFFER_LENGTH_IN_BYTES = 40000
+    # ======= I2S CONFIGURATION =======
+
+elif os.uname().machine.count("MIMXRT"):
+    from machine import SDCard
+
+    # sd = SDCard(1)  # Teensy 4.1: sck=45, mosi=43, miso=42, cs=44
+    # os.mount(sd, "/sd")
+
+    # ======= I2S CONFIGURATION =======
+    SCK_PIN = 4
+    WS_PIN = 3
+    SD_PIN = 2
+    I2S_ID = 2
+    BUFFER_LENGTH_IN_BYTES = 40000
+    # ======= I2S CONFIGURATION =======
+
+else:
+    print("Warning: program not tested with this board")
+
+# ======= AUDIO CONFIGURATION =======
+WAV_FILE = "test.wav"
+WAV_SAMPLE_SIZE_IN_BITS = 16
+FORMAT = I2S.MONO
+SAMPLE_RATE_IN_HZ = 16000
+# ======= AUDIO CONFIGURATION =======
+
+PLAY = 0
+PAUSE = 1
+RESUME = 2
+STOP = 3
+
+
+def eof_callback(arg):
+    global state
+    print("end of audio file")
+    # state = STOP  # uncomment to stop looping playback
+
+
+def i2s_callback(arg):
+    global state
+    if state == PLAY:
+        num_read = wav.readinto(wav_samples_mv)
+        # end of WAV file?
+        if num_read == 0:
+            # end-of-file, advance to first byte of Data section
+            pos = wav.seek(44)
+            _ = audio_out.write(silence)
+            micropython.schedule(eof_callback, None)
+        else:
+            _ = audio_out.write(wav_samples_mv[:num_read])
+    elif state == RESUME:
+        state = PLAY
+        _ = audio_out.write(silence)
+    elif state == PAUSE:
+        _ = audio_out.write(silence)
+    elif state == STOP:
+        # cleanup
+        wav.close()
+        # if os.uname().machine.count("PYBD"):
+        #    os.umount("/sd")
+        # elif os.uname().machine.count("ESP32"):
+        #    os.umount("/sd")
+        #    sd.deinit()
+        # elif os.uname().machine.count("Raspberry"):
+        #    os.umount("/sd")
+        #    spi.deinit()
+        # elif os.uname().machine.count("MIMXRT"):
+        #    os.umount("/sd")
+        #    sd.deinit()
+        audio_out.deinit()
+        print("Done")
+    else:
+        print("Not a valid state.  State ignored")
+
+
+audio_out = I2S(
+    I2S_ID,
+    sck=Pin(SCK_PIN),
+    ws=Pin(WS_PIN),
+    sd=Pin(SD_PIN),
+    mode=I2S.TX,
+    bits=WAV_SAMPLE_SIZE_IN_BITS,
+    format=FORMAT,
+    rate=SAMPLE_RATE_IN_HZ,
+    ibuf=BUFFER_LENGTH_IN_BYTES,
+)
+
+audio_out.irq(i2s_callback)
+state = PAUSE
+
+wav = open("/lib/audio_files/{}".format(WAV_FILE), "rb")
+_ = wav.seek(44)  # advance to first byte of Data section in WAV file
+
+# allocate a small array of blank samples
+silence = bytearray(1000)
+
+# allocate sample array buffer
+wav_samples = bytearray(10000)
+wav_samples_mv = memoryview(wav_samples)
+
+_ = audio_out.write(silence)
+
+# add runtime code here ....
+# changing 'state' will affect playback of audio file
+
+print("starting playback for 10s")
+state = PLAY
+time.sleep(10)
+print("pausing playback for 10s")
+state = PAUSE
+time.sleep(10)
+print("resuming playback for 15s")
+state = RESUME
+time.sleep(15)
+print("stopping playback")
+state = STOP
+
+
+def demo():
+    print("Audio demo")
+
+
+if __name__ == "__main__":
+    demo()
diff --git a/lib/audio_files/beep.mp3 b/lib/audio_files/beep.mp3
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diff --git a/lib/audio_files/test.mp3 b/lib/audio_files/test.mp3
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diff --git a/lib/audio_files/test.wav b/lib/audio_files/test.wav
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