Sound piezo buzzer for straight key

vail-adapter.ino

@@ -11,11 +11,13 @@
 #  define DIT_PIN 2
 #  define DAH_PIN 1
 #  define KEY_PIN 0
+#  define PIEZO 7
 #  define LED_ON false
 #else
 #  define DIT_PIN 12
 #  define DAH_PIN 11
 #  define KEY_PIN 10
+#  define PIEZO 8
 #  define LED_ON true
 #endif
 #define LED_OFF (!LED_ON)
@@ -23,39 +25,61 @@
 #define STRAIGHT_KEY ','
 #define DIT_KEY KEY_LEFT_CTRL
 #define DAH_KEY KEY_RIGHT_CTRL
+#define TONE 660
+
+#define MILLISECOND 1
+#define SECOND (1 * MILLISECOND)
 
-bool iambic = true;
 bool keyboard = true;
+bool trs = false; // true if a TRS plug is in a TRRS jack
+uint16_t iambicDelay = 80 * MILLISECOND;
 Bounce dit = Bounce();
 Bounce dah = Bounce();
 Bounce key = Bounce();
 
 void setup() {
   pinMode(LED_BUILTIN, OUTPUT);
+  pinMode(PIEZO, OUTPUT);
   dit.attach(DIT_PIN, INPUT_PULLUP);
   dah.attach(DAH_PIN, INPUT_PULLUP);
   key.attach(KEY_PIN, INPUT_PULLUP);
   
   Keyboard.begin();
 
-  // Straight keys need to wire the dah pin to ground somehow.
-  // The easiest way I can think of to do this is to use a TS connector
-  // instead of a TRS connector.
+  // To auto-sense a straight key in a TRRS jack,
+  // we just check to see if DAH is closed. 
+  // The sleeve on the straight key's TRS plug
+  // will short the second ring to the sleeve.
   for (int i = 0; i < 16; i++) {
     delay(20);
     dah.update();
   }
   if (dah.read() == LOW) {
-    iambic = false;
-  } else {
-    iambic = true;
+    trs = true;
   }
+}
 
-  // Blink out a V
-  for (int i = 0; i < 4; i++) {
-    digitalWrite(LED_BUILTIN, LED_ON); delay(80 + (i/3)*160);
-    digitalWrite(LED_BUILTIN, LED_OFF); delay(80 + (i/3)*160);
+// A reentrant doodad to blink out the letter V at startup
+// After startup, display the status of the keyboard
+#define HELLO_BITS 0b0000101010111000
+void setLED() {
+  static bool beepin = false;
+  int beat = millis() / iambicDelay;
+  bool on = keyboard; // If we're not in intro, display status of keyboard
+
+  if (beat < 16) {
+    on = HELLO_BITS & (1 << (15-beat));
+    if (on != beepin) {
+      if (on) {
+        tone(PIEZO, TONE);
+      } else {
+        noTone(PIEZO);
+      }
+      beepin = on;
+    }
   }
+  
+  digitalWrite(LED_BUILTIN, on?LED_ON:LED_OFF);
 }
 
 void midiKey(bool down, uint8_t key) {
@@ -66,54 +90,57 @@ void midiKey(bool down, uint8_t key) {
 
 void midiProbe() {
   midiEventPacket_t event = MidiUSB.read();
-  if (event.byte1 == 0x80) { 
-    // Key release, channel 0
-    if (event.byte2 == 0x00) { 
-      // C0 note
-      keyboard = false;
-    }
-  }  
+
+  uint16_t msg = (event.byte1 << 8) | (event.byte2 << 0);
+  switch (msg) {
+  case 0x8B00: // Controller 0: turn keyboard mode on/off
+    keyboard = (event.byte3 > 0x3f);
+    break;
+  case 0x8B01: // Controller 1: set iambic speed (0-254)
+    iambicDelay = event.byte3 << 1;
+    break;
+  }
 }
 
 void loop() {
   midiProbe();
-  digitalWrite(LED_BUILTIN, keyboard?LED_ON:LED_OFF);
+  setLED();
 
   // Monitor straight key pin
   if (key.update()) {
     midiKey(key.fell(), 0);
-    if (keyboard) {
-      if (key.fell()) {
+    if (key.fell()) {
+      tone(PIEZO, TONE);
+      if (keyboard) {
         Keyboard.press(STRAIGHT_KEY);
-      } else {
+      }
+    } else {
+      noTone(PIEZO);
+      if (keyboard) {
         Keyboard.release(STRAIGHT_KEY);
       }
     }
   }
-  
-  // Monitor dit pin, which could be straight key if dah was closed on boot
+
+  // If we made dit = dah, we have a straight key on the dit pin,
+  // so we skip iambic polling.
+  if (trs) {
+    return;
+  }
+
   if (dit.update()) {
-    uint8_t kbdKey, mKey;
-    if (iambic) {
-      kbdKey = DIT_KEY;
-      mKey = 1;
-    } else {
-      kbdKey = STRAIGHT_KEY;
-      mKey = 0;
-    }
-    
-    midiKey(dit.fell(), mKey);
+    midiKey(dit.fell(), 1);
     if (keyboard) {
       if (dit.fell()) {
-        Keyboard.press(kbdKey);
+        Keyboard.press(DIT_KEY);
       } else {
-        Keyboard.release(kbdKey);
+        Keyboard.release(DAH_KEY);
       }
     }
   }
   
   // Monitor dah pin
-  if (iambic && dah.update()) {
+  if (dah.update()) {
     midiKey(dah.fell(), 2);
     
     if (keyboard) {