Organizing the arduino things a bit

arduino/misc/SerialEcho/Makefile

@@ -0,0 +1 @@
+../../arduino.mk

arduino/misc/SerialEcho/SerialEcho.ino

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+const unsigned int BAUD_RATE = 9600;
+unsigned int keys = 0;
+
+void setup() {
+    Serial.begin(BAUD_RATE);
+    Serial.print("> ");
+}
+
+void loop() {
+    if (Serial.available() <= 0) {
+        return;
+    }
+
+    Serial.write(Serial.read());
+    keys++;
+
+    if (keys == 100) {
+        Serial.println("\nKABOOM!!!");
+        keys = 0;
+        Serial.print("> ");
+        return;
+    }
+
+    Serial.println("");
+    Serial.print(keys);
+    Serial.println(" keys pressed");
+    Serial.print("> ");
+}