add PWM audio example

micropython/examples/pico_explorer/noise.py

@@ -0,0 +1,141 @@
+# This example shows you how you can use Pico Explorer's onboard buzzer as a speaker to play different notes and string them together into a bleepy tune.
+# It uses code written by Avram Piltch - check out his Tom's Hardware article! https://www.tomshardware.com/uk/how-to/buzzer-music-raspberry-pi-pico
+# You'll need to connect a jumper wire between GPO and AUDIO on the Explorer Base to hear noise.
+
+import utime
+import picoexplorer as explorer
+
+# Set up and initialise Pico Explorer
+buf = bytearray(explorer.get_width() * explorer.get_height() * 2)
+explorer.init(buf)
+
+# tells Pico Explorer which pin you'll be using for noise
+explorer.set_audio_pin(0)
+
+# this handy list converts notes into frequencies, which you can use with the explorer.set_tone function
+tones = {
+"B0": 31,
+"C1": 33,
+"CS1": 35,
+"D1": 37,
+"DS1": 39,
+"E1": 41,
+"F1": 44,
+"FS1": 46,
+"G1": 49,
+"GS1": 52,
+"A1": 55,
+"AS1": 58,
+"B1": 62,
+"C2": 65,
+"CS2": 69,
+"D2": 73,
+"DS2": 78,
+"E2": 82,
+"F2": 87,
+"FS2": 93,
+"G2": 98,
+"GS2": 104,
+"A2": 110,
+"AS2": 117,
+"B2": 123,
+"C3": 131,
+"CS3": 139,
+"D3": 147,
+"DS3": 156,
+"E3": 165,
+"F3": 175,
+"FS3": 185,
+"G3": 196,
+"GS3": 208,
+"A3": 220,
+"AS3": 233,
+"B3": 247,
+"C4": 262,
+"CS4": 277,
+"D4": 294,
+"DS4": 311,
+"E4": 330,
+"F4": 349,
+"FS4": 370,
+"G4": 392,
+"GS4": 415,
+"A4": 440,
+"AS4": 466,
+"B4": 494,
+"C5": 523,
+"CS5": 554,
+"D5": 587,
+"DS5": 622,
+"E5": 659,
+"F5": 698,
+"FS5": 740,
+"G5": 784,
+"GS5": 831,
+"A5": 880,
+"AS5": 932,
+"B5": 988,
+"C6": 1047,
+"CS6": 1109,
+"D6": 1175,
+"DS6": 1245,
+"E6": 1319,
+"F6": 1397,
+"FS6": 1480,
+"G6": 1568,
+"GS6": 1661,
+"A6": 1760,
+"AS6": 1865,
+"B6": 1976,
+"C7": 2093,
+"CS7": 2217,
+"D7": 2349,
+"DS7": 2489,
+"E7": 2637,
+"F7": 2794,
+"FS7": 2960,
+"G7": 3136,
+"GS7": 3322,
+"A7": 3520,
+"AS7": 3729,
+"B7": 3951,
+"C8": 4186,
+"CS8": 4435,
+"D8": 4699,
+"DS8": 4978
+}
+
+# put the notes for your song in here!
+song = ["F6","F6","E6","F6","F5","P","F5","P","C6","AS5","A5","C6","F6","P","F6","P","G6","FS6","G6","G5","P","G5","P","G6","F6","E6","D6","C6","P","C6","P","D6","E6","F6","E6","D6","C6","D6","C6","AS5","A5","AS5","A5","G5","F5","G5","F5","E5","D5","C5","D5","E5","F5","G5","AS5","A5","G5","A5","F5","P","F5"]
+
+def clear():                        # this function clears Pico Explorer's screen to black
+    explorer.set_pen(0,0,0)
+    explorer.clear()
+    explorer.update()
+    
+def playtone(frequency):            # this function tells your program how to make noise
+    explorer.set_tone(frequency)
+
+def bequiet():                      # this function tells your program how not to make noise
+    explorer.set_tone(-1000)
+
+def playsong(song):                 # this function plays your song
+    a = 0                           # this variable keeps track of the visualiser bars
+    for i in range(len(song)):
+        if (song[i] == "P"):
+            bequiet()
+        else:
+            playtone(tones[song[i]])
+            explorer.set_pen(0, 255, 0)  # switch to green pen
+            explorer.rectangle(a, 240 - (int((tones[song[i]])/21)), 5, 240) # draw a green bar corresponding to the frequency of the note
+            a += 7
+        if a >= 240:  # clears the screen if the green bars reach the right hand edge
+            clear()
+            a = 0
+        explorer.update()
+        utime.sleep(0.15)  # change this number if you want to alter how long the notes play for
+    bequiet()
+
+clear()
+playsong(song)
+clear()