commit 2ac64169ef2f7396530adc2323aec0c43f7fa8eb
Author: Nicolas MASSE <nicolas.masse@itix.fr>
Date:   Sun Apr 8 19:56:15 2018 +0200

    first commit

diff --git a/main.ino b/main.ino
new file mode 100644
index 0000000..266f15e
--- /dev/null
+++ b/main.ino
@@ -0,0 +1,130 @@
+/*
+  A seven segement display counter
+
+  Counts the number of times a button is pressed and displays this number on a 7 segment display
+
+  Nicolas Massé
+*/
+
+/*
+ * The button is connected to PIN 2.
+ * 
+ * To prevent any rebound issue, filter the button signal with a low pass filter (R = 240 ohms, C = 6.8 micro farad)
+ */
+#define BUTTON_PIN 2
+
+/*
+ * The seven segment display has a common cathode for each digit
+ */
+#define CATHODE_1000_PIN 1
+#define CATHODE_100_PIN 13
+#define CATHODE_10_PIN 3
+#define CATHODE_1_PIN 4
+// The splitter is the colon between the second and third digit
+#define CATHODE_SPLITTER_PIN 0
+
+/*
+ * The anodes will light up a segment when it is LOW and the cathode is HIGH.
+ * 
+ * The anode numbering refers to the standard numbering:
+ * https://en.wikipedia.org/wiki/Seven-segment_display
+ */
+#define ANODE_A_PIN 11
+#define ANODE_B_PIN 10
+#define ANODE_C_PIN 9
+#define ANODE_D_PIN 8
+#define ANODE_E_PIN 7
+#define ANODE_F_PIN 6
+#define ANODE_G_PIN 5
+
+/*
+ * The number of milliseconds to wait in order to let the retinal persistence do its job. 
+ * See https://en.wikipedia.org/wiki/Persistence_of_vision
+ */
+#define DELAY 5
+
+/*
+ * Set this in order to see how the display multiplexing work
+ */
+//#define DEBUG
+
+#ifdef DEBUG
+#define DELAY_DEBUG delay(50);
+#define DELAY 500
+#else
+#define DELAY_DEBUG 
+#endif
+
+// The state of each anode for each number between 0 and 9
+#define ANODE_A_STATE(x) (x != 4 && x != 1 ? LOW : HIGH)
+#define ANODE_B_STATE(x) (x != 5 && x != 6 ? LOW : HIGH)
+#define ANODE_C_STATE(x) (x != 2 ? LOW : HIGH)
+#define ANODE_D_STATE(x) (x != 1 && x != 4 && x != 7 ? LOW : HIGH)
+#define ANODE_E_STATE(x) (x != 0 && x != 2 && x != 6 && x != 8 ? HIGH : LOW)
+#define ANODE_F_STATE(x) (x != 1 && x != 2 && x != 3 && x != 7 ? LOW : HIGH)
+#define ANODE_G_STATE(x) (x != 0 && x != 1 && x != 7 ? LOW : HIGH)
+
+// All the cathodes
+const int cathodes[] = {CATHODE_1000_PIN, CATHODE_100_PIN, CATHODE_10_PIN, CATHODE_1_PIN, CATHODE_SPLITTER_PIN};
+
+// All the anodes
+const int anodes[] = {ANODE_A_PIN, ANODE_B_PIN, ANODE_C_PIN, ANODE_D_PIN, ANODE_E_PIN, ANODE_F_PIN, ANODE_G_PIN};
+
+void setup() {
+  // cathodes as output with default to LOW
+  for (int i = 0; i < sizeof(cathodes)/sizeof(cathodes[0]); i++) {
+    pinMode(cathodes[i], OUTPUT);
+    digitalWrite(cathodes[i], LOW);
+  }
+  // anodes as output with default to HIGH
+  for (int i = 0; i < sizeof(anodes)/sizeof(anodes[0]); i++) {
+    pinMode(anodes[i], OUTPUT);
+    digitalWrite(anodes[i], HIGH);
+  }
+  
+  // Enable the button and register an interrupt
+  pinMode(BUTTON_PIN, INPUT);
+  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), button_interrupt, RISING);
+}
+
+// the counter is later incremented by an interrupt
+volatile int counter = 0;
+
+
+void button_interrupt() {
+  counter++;
+}
+
+void loop() {
+  int n = counter;
+
+  // Base 10 conversion
+  int n1 = n % 10;
+  int n10 = ((n - n1) % 100) / 10;
+  int n100 = ((n - n1 - n10 * 10) % 1000) / 100;
+  int n1000 = ((n - n1 - n10 * 10 - n100 * 100) % 10000) / 1000;
+
+  int digits[] = { n1000, n100, n10, n1 };
+  for (int c = 0; c < 4; c++) {
+    int digit = digits[c];
+    digitalWrite(cathodes[c], HIGH);
+    DELAY_DEBUG
+    digitalWrite(ANODE_A_PIN, ANODE_A_STATE(digit));
+    DELAY_DEBUG
+    digitalWrite(ANODE_B_PIN, ANODE_B_STATE(digit));
+    DELAY_DEBUG
+    digitalWrite(ANODE_C_PIN, ANODE_C_STATE(digit));
+    DELAY_DEBUG
+    digitalWrite(ANODE_D_PIN, ANODE_D_STATE(digit));
+    DELAY_DEBUG
+    digitalWrite(ANODE_E_PIN, ANODE_E_STATE(digit));
+    DELAY_DEBUG
+    digitalWrite(ANODE_F_PIN, ANODE_F_STATE(digit));
+    DELAY_DEBUG
+    digitalWrite(ANODE_G_PIN, ANODE_G_STATE(digit));
+    delay(DELAY);
+    digitalWrite(cathodes[c], LOW);
+    DELAY_DEBUG
+  }
+}
+