1 files changed, 93 insertions, 0 deletions
diff --git a/esp32/lego-piano.ino b/esp32/lego-piano.ino
new file mode 100644
index 0000000..81f75c9
--- /dev/null
+++ b/esp32/lego-piano.ino
@@ -0,0 +1,93 @@
+/*
+  matrix-scan a set of LEDs
+
+  pins:
+
+  "rows" 12 & 13 go to a 220Ω resistor, then to 2 LEDs each (positive
+  / long stem side); also to a 10kΩ resistor then to 2
+  phototransistors (collector / long stem side)
+
+  also, from between the 10kΩ and the phototransistors, wire goes to
+  A1 & A2
+
+  "columns"
+  14 & 15 go to 2 LEDs each (negative / short stem side)
+
+  so that given one of 12|13 and one of 14|15, one LED is identified
+ */
+
+int currentLed = 0;
+
+void setup() {
+  Serial.begin(19200);
+  pinMode(12, OUTPUT);
+  pinMode(13, OUTPUT);
+  pinMode(14, OUTPUT);
+  pinMode(15, OUTPUT);
+  pinMode(A1, INPUT);
+  pinMode(A2, INPUT);
+  currentLed = 0;
+}
+
+void tristate(int pin) {
+  pinMode(pin,OUTPUT);
+  digitalWrite(pin,LOW);
+  pinMode(pin,INPUT);
+}
+
+void power(int pin) {
+  pinMode(pin,OUTPUT);
+  digitalWrite(pin,HIGH);
+}
+
+void ground(int pin) {
+  pinMode(pin,OUTPUT);
+  digitalWrite(pin,LOW);
+}
+
+void enableLed(int led) {
+  int row = led/2;
+  int col = led%2;
+  /* Serial.print("enabling "); */
+  /* Serial.print(row); */
+  /* Serial.print(" "); */
+  /* Serial.println(col); */
+
+  if (row==0) {
+    power(12); ground(13);
+  }
+  else {
+    ground(12); power(13);
+  }
+
+  if (col==0) {
+    ground(14); tristate(15);
+  }
+  else {
+    tristate(14); ground(15);
+  }
+}
+
+int sense(int led) {
+  int row = led/2;
+
+  int value = analogRead(row == 0 ? A1 : A2);
+
+  //Serial.println(value);
+  return value < 500;
+}
+
+void loop() {
+  /* Serial.print("current led "); */
+  /* Serial.println(currentLed); */
+
+  enableLed(currentLed);
+  delay(20);
+  if (sense(currentLed)) {
+    Serial.print(currentLed);
+    Serial.println(" proximity!");
+  }
+
+  currentLed = (currentLed+1)%4;
+  delay(20);
+}
+\ No newline at end of file