PE1-4.3 Interfacing Displays & Sensors
You can use the serial monitor for debugging, drive LEDs and an LCD with static and scrolling messages, and interface temperature, humidity, IR, gas, PIR and ultrasonic sensors and a DC motor.
The serial monitor is your only window into a running board, so treat it as the primary debugging tool rather than an afterthought. Each sensor teaches a different interface style: analog voltage, digital pulse width, a timed echo — and the ultrasonic sensor in particular is really a stopwatch measuring time of flight. The DC motor is where you learn that a microcontroller pin cannot drive a load directly and that a motor's back-EMF will damage things without a driver stage.
Work through these
Working with the serial monitor
Printing to your own machine, which is the only debugging tool you have at first. It is worth setting up properly before anything else in this topic.
LED interfacing
The first output device, and the one that verifies your wiring and your upload in one step. Current limiting is the detail that keeps the pin alive.
LCD interfacing; fixed one-line static message display
The first display with real information on it, and the wiring and library that drive it. Getting a static message up is the milestone.
Running (scrolling) message display
Making the message move, which is the first time your code has to manage state over time. It is also where the blocking delay problem from the previous topic bites.
Temperature and humidity sensor interfacing
The first input sensor, which returns a real measurement rather than a level. It introduces the idea of a sensor with its own protocol.
IR sensor and gas detection sensor
Two sensors that answer yes or no about the world. They are cheap, and their limitations are worth measuring rather than reading.
PIR sensor
Detecting people by their heat, which is the sensor behind most security applications. Its warm-up time and re-trigger behaviour surprise people.
Ultrasonic sensor: time-of-flight measurement
Measuring distance by timing an echo, which is the first sensor where you compute the answer yourself. It connects the timing functions to a physical quantity.
DC motor interfacing and why a driver stage is needed
Driving something that needs real current, and why the pin cannot do it alone. This is the item that stops a beginner destroying a board.
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