Today we're going to give Robby some sensors, he can move his motors and take inputs from our controller, but now we want him to see the world and control himself.
This device is what Robby will use to see.
It shines and infrared light and measure how much is reflected, so if there's nothing near it, nothing will reflect.
If it's close to something that reflects the light, then it'll trigger the OUT pin, which we can read just like a button.
So we connect VCC on the sensor to 3v3 on our microcontroller.
GND on the sensor to GND on our microcontroller.
And OUT on the sensor to D4 on our microcontroller.
int sensorPin = 4;
void setup() {
Serial.begin(115200);
pinMode(sensorPin, INPUT);
}
void loop() {
Serial.println(digitalRead(sensorPin));
delay(10); // wait 0.01 sec
}
That's all we need, now if you wave your hand over the sensor you should see the light on the sensor come on, and the state should also be printed in our Serial Monitor.
Now that we know there is something in the way, we need to make Robby actually do something different to avoid it.
For this we need to use something called CONDITIONALS.
The most common is called an IF statement. We write if (){} and everything within the () is judged to be true(1) or false(0).
If it is true or "1" then we do the code inside the {}, otherwise that code is skipped.
When we add an } else {} then the code in the else block is only run if the code inthe IF is not.
int sensorPin = 4;
void setup() {
Serial.begin(115200);
pinMode(sensorPin, INPUT);
}
void loop() {
if (digitalRead(sensorPin)){
Serial.println("STOP!");
} else {
Serial.println("GO FORWARD");
}
delay(10); // wait 0.01 sec
}
So the code above will check if the digitalRead(sensorPin) gives a 1 or a 0.
If it's a 0, then we print "GO FORWARD", or else if it's a 1 we print "STOP!".
We don't have a second sensor yet, but we can imagine how the code could be even better if we had one on the left and one on the right.
int sensorPinLeft = 4;
int sensorPinRight = 5;
void setup() {
Serial.begin(115200);
pinMode(sensorPinLeft, INPUT);
pinMode(sensorPinRight, INPUT);
}
void loop() {
if (digitalRead(sensorPinLeft) && digitalRead(sensorPinRight)){ // theres something on the
Serial.println("Stop"); // left AND on the right
} else if (digitalRead(sensorPinLeft)){ // else if theres something on the left
Serial.println("Turn Right");
} else if (digitalRead(sensorPinRight)){ // else if there's something on the right
Serial.println("Turn Left");
} else {
Serial.println("Go Forward!");
}
delay(10); // wait 0.01 sec
}
Read this one carefully to understand what it does.
When IF ELSE blocks are strung together like this, only one of the blocks will actually be run, the rest will be skipped.
Note the first block that checks both left and right. The && symbol needs both of the values to be 1, if it's 1 and 0 it will be skipped.