Merge branch 'master' of github.com:adafruit/Adafruit_Learning_System_Guides

Trinket_Gemma_Mini_Theramin/Trinket_Gemma_Mini_Theramin.ino

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+/* Adafruit Trinket/Gemma Example: Simple Theramin
+
+  Read the voltage from a Cadmium Sulfide (CdS) photocell voltage
+  divider and output a corresponding tone to a piezo buzzer
+
+  Wiring: Photocell voltage divider center wire to GPIO #2
+  (analog 1) and output tone to GPIO #0 (digital 0)
+
+  Note: The Arduino tone library does not work for the ATTiny85 on the
+  Trinket and Gemma.  The beep function below is similar.  The beep
+  code is adapted from Dr. Leah Buechley at
+  http://web.media.mit.edu/~leah/LilyPad/07_sound_code.html
+*/
+
+#define SPEAKER   0    // Speaker connected to this DIGITAL pin #
+#define PHOTOCELL 1    // CdS photocell connected to this ANALOG pin #
+#define SCALE     2.0  // You can change this to change the tone scale
+
+void setup() {
+  // Set SPEAKER pin to output to drive the piezo buzzer (important)
+  pinMode(SPEAKER, OUTPUT);
+}
+
+void loop() {
+  // Read PHOTOCELL analog pin for the current CdS divider voltage
+  int reading = analogRead(PHOTOCELL);
+  // Change the voltage to a frequency.  You can change the values
+  // to scale your frequency range.
+  int freq = 220 + (int)(reading * SCALE);
+  // Output the tone to SPEAKER pin.  You can change the '400'
+  // to different times (in milliseconds).
+  beep(SPEAKER, freq, 400);
+  delay(50); // Delay a bit between notes (also adjustable to taste)
+}
+
+// The sound-producing function
+void beep (unsigned char speakerPin, int frequencyInHertz, long timeInMilliseconds)
+{ // http://web.media.mit.edu/~leah/LilyPad/07_sound_code.html
+  int  x;
+  long delayAmount = (long)(1000000 / frequencyInHertz);
+  long loopTime = (long)((timeInMilliseconds * 1000) / (delayAmount * 2));
+  for (x = 0; x < loopTime; x++) {
+    digitalWrite(speakerPin, HIGH);
+    delayMicroseconds(delayAmount);
+    digitalWrite(speakerPin, LOW);
+    delayMicroseconds(delayAmount);
+  }
+}

Trinket_Gemma_Mini_Theramin/Trinket_Gemma_Mini_Theramin.py

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+# Adafruit Trinket/Gemma Example: Simple Theramin
+# Read the voltage from a Cadmium Sulfide (CdS) photocell voltage
+# divider and output a corresponding tone to a piezo buzzer
+#
+# Photocell voltage divider center wire to GPIO #2 (analog 1)
+# and output tone to GPIO #0 (digital 0)
+
+import board
+import analogio
+import digitalio
+import time
+
+speaker_pin   = board.D0  # Speaker is connected to this DIGITAL pin
+photocell_pin = board.A1  # CdS photocell connected to this ANALOG pin
+scale         = 0.03      # Change this to adjust tone scale
+
+readpin  = analogio.AnalogIn(photocell_pin)
+writepin = digitalio.DigitalInOut(speaker_pin)
+writepin.direction = digitalio.Direction.OUTPUT
+
+while True:  # Loop forever...
+	# Read photocell analog pin and convert voltage to frequency
+	freq_hz = 220 + readpin.value * scale
+
+	delay_amount = 0.5 / freq_hz     # 1/2 Frequency
+	note_start   = time.monotonic()  # Time when note started
+	while time.monotonic() - note_start < 0.4:  # For 400 milliseconds...
+		writepin.value = True    # Set pin high
+		time.sleep(delay_amount) # Wait for 1/2 of note frequency
+		writepin.value = False   # Set pin low
+		time.sleep(delay_amount) # Wait for other 1/2 of note freq.
+
+	time.sleep(0.05)  # Delay 50 ms between notes (also adjustable)