Several fixes and additions.

MIDI-Host-Adapter.ino

@@ -14,11 +14,16 @@ bool swap_nibbles = false;
 bool high_freq = false;
 
 #define BRIGHTNESS 6
+#define INITIAL_MIDI_CHANNEL 1
 #define BUTTON_DEBOUNCE_TIME_MS 50
+#define BUTTON_DOUBLE_PRESS_MS 200
+#define BLINK_FREQUENCY_MS 500
 
 // Constructor object
 TM1638plus_Model2 tm(STROBE_TM, CLOCK_TM, DIO_TM, swap_nibbles, high_freq);
 elapsedMillis button_debounce_timer;
+elapsedMillis blink_timer;
+elapsedMillis double_press_timer;
 
 void setup() {
   Serial.begin(9600);
@@ -34,10 +39,8 @@ void setup() {
   pinMode(MIDI_CH_BIT2, OUTPUT);
   pinMode(MIDI_CH_BIT1, OUTPUT);
   pinMode(MIDI_CH_BIT0, OUTPUT);
-  digitalWrite(MIDI_CH_BIT3, LOW);
-  digitalWrite(MIDI_CH_BIT2, LOW);
-  digitalWrite(MIDI_CH_BIT1, LOW);
-  digitalWrite(MIDI_CH_BIT0, LOW);
+
+  SetMidiChannel(INITIAL_MIDI_CHANNEL);
 
   delay(500);
 
@@ -46,21 +49,44 @@ void setup() {
 
 void loop() {
   uint8_t button;
+  static uint8_t actual_channel;
+  static uint8_t new_channel;
+
+  if (actual_channel == 0) {
+    actual_channel = 1;
+    tm.DisplayDecNum(actual_channel, 0, false, TMAlignTextRight);
+  }
 
   button = tm.ReadKey16();
-  if (button > 0 && button_debounce_timer > BUTTON_DEBOUNCE_TIME_MS) {
-    Serial.print("Button: ");
+
+  if (button > 0 && button_debounce_timer > BUTTON_DEBOUNCE_TIME_MS && double_press_timer > BUTTON_DOUBLE_PRESS_MS) {
+    // Button pressed once
+    Serial.print("Button once: ");
     Serial.println(button, DEC);
     button_debounce_timer = 0;
-    tm.DisplayDecNum(button, 0, false, TMAlignTextRight);
-
-    SetMidiChannel(button);
-  }
+    blink_timer = 0;
+    new_channel = button;
+    tm.DisplayDecNumNibble(new_channel, actual_channel, 0, false, TMAlignTextRight);
+  } else if (button > 0 && button_debounce_timer > BUTTON_DEBOUNCE_TIME_MS && double_press_timer < BUTTON_DOUBLE_PRESS_MS && button == new_channel) {
+    // Button pressed twice
+    Serial.print("Button twice: ");
+    Serial.println(button, DEC);
+    actual_channel = new_channel;
+    SetMidiChannel(actual_channel);
+    double_press_timer = 0;
+  } else if (actual_channel != new_channel)
+    if (blink_timer > BLINK_FREQUENCY_MS) {
+      blink_timer = 0;
+      tm.DisplayDecNum(actual_channel, 0, false, TMAlignTextRight);
+    } else if (blink_timer > BLINK_FREQUENCY_MS / 2) {
+      tm.DisplayDecNumNibble(new_channel, actual_channel, 0, false, TMAlignTextRight);
+    }
 }
 
 void SetMidiChannel(uint8_t channel) {
   Serial.print("Setting MIDI channel: ");
   Serial.print(channel, DEC);
+  channel--;
   Serial.print(" (");
   printBinary(channel, 4);
   Serial.println(")");