add arduino sketch and update readme

PumpStateMachine.ino

@@ -0,0 +1,83 @@
+#include <StateMachine.h>
+
+const int lowTriggerPin = 2;
+const int highTriggerPin = 3;
+const int ledPin =  13; // the number of the LED pin
+const int relay = 7;
+
+StateMachine machine = StateMachine();
+
+State* S0 = machine.addState(&state0); // Waiting for trigger
+State* S1 = machine.addState(&state1); // Pump
+State* S2 = machine.addState(&state2); // Stop Pump
+
+void setup() {
+  Serial.begin(115200);
+  // initialize the LED pin as an output:
+  pinMode(ledPin, OUTPUT);
+  // initialize the waterlevel sensors pin as an input:
+  pinMode(lowTriggerPin, INPUT);
+  pinMode(highTriggerPin, INPUT);
+  // initialize the relay pin:
+  pinMode(relay, OUTPUT);
+
+  S0->addTransition(&transitionS0S1,S1);  // S0 transition to S1
+  S1->addTransition(&transitionS1S2,S2);  // S1 transition to S2
+  S2->addTransition(&transitionS2S0,S0);  // S2 transition to S0
+  S2->addTransition(&transitionS2S1,S1);  // S2 transition to S1
+}
+
+void loop() { 
+  machine.run();
+}
+
+void state0(){
+  Serial.println("State 0");
+  Serial.println("waiting for trigger");
+}
+
+bool transitionS0S1(){
+  if(digitalRead(lowTriggerPin) == HIGH && digitalRead(highTriggerPin) == HIGH){
+    return true;
+  }
+  // Should never happen...
+  if(digitalRead(lowTriggerPin) == LOW && digitalRead(highTriggerPin) == HIGH){ 
+    return true;
+  }
+  return false;
+}
+
+void state1(){
+  Serial.println("State 1");
+  Serial.println("Start pumping...");
+  digitalWrite(ledPin, HIGH);
+  digitalWrite(relay, HIGH);
+}
+
+bool transitionS1S2(){
+  if(digitalRead(lowTriggerPin) == LOW && digitalRead(highTriggerPin) == LOW){
+    return true;
+  }
+  return false;
+}
+
+void state2(){
+  Serial.println("State 1");
+  Serial.println("Stop pumping...");
+  digitalWrite(ledPin, LOW);
+  digitalWrite(relay, LOW);
+}
+
+bool transitionS2S0(){
+  if(digitalRead(lowTriggerPin) == LOW && digitalRead(highTriggerPin) == LOW){
+    return true;
+  }
+  return false;
+}
+
+bool transitionS2S1(){
+  if(digitalRead(lowTriggerPin) == HIGH && digitalRead(highTriggerPin) == LOW){
+    return true;
+  }
+  return false;
+}