Keyboard: Read digit (untested)

firmware/src/keyboard.cpp

@@ -21,7 +21,14 @@ row/col 0 1 2 3
 */
 
 typedef uint8_t Key;
+
+const char *allKeys = "123A456B789C*0#D";
 #define KEY_NONE 255
+const uint8_t digits[16] =
+  { 1, 2, 3, KEY_NONE,
+    4, 5, 6, KEY_NONE,
+    7, 8, 9, KEY_NONE,
+    KEY_NONE, 0, KEY_NONE, KEY_NONE};
 
 bool setupKeyboard() {
   if (!kbd.begin()) {
@@ -37,16 +44,26 @@ bool setupKeyboard() {
 }
 
 Key getPressedKey();
+uint8_t getPressedDigit(Key key);
 
 #define KBD_COL_MASK 0b11110000
 #define KBD_ROW_MASK 0b00001111
 
 void demoKeyboard() {
-  String allKeys = F("123A456B789C*0#D");
   auto key = getPressedKey();
   if (key != KEY_NONE) {
     Serial.print("Key pressed: ");
-    Serial.println(allKeys[key]);
+    Serial.print(allKeys[key]);
+
+    auto digit = getPressedDigit(key);
+    if (digit != KEY_NONE) {
+      Serial.print(", digit: ");
+      Serial.print(digit);
+    } else {
+      Serial.print(" (Not a digit)");
+    }
+
+    Serial.println();
   }
 }
 
@@ -89,3 +106,11 @@ Key getPressedKey() {
   // return key
   return (rowPressed * 4) + colPressed;
 }
+
+/**
+ * Returns pressed digit or KEY_NONE if the key is not a digit
+ */
+uint8_t getPressedDigit(Key key) {
+  if (key == KEY_NONE) return KEY_NONE;
+  return digits[key];
+}