Arduino Tutorial 27: Understanding Pushbuttons and Pull Up and Pull Down Resistors

Being able to add push buttons to your projects adds important new capabilities to your prototypes. It is a clever way you can get input from a user. You could imagine using push buttons to turn something on or off, or they could be used to set motor speed or direction. In order to incorporate buttons into a project, you need to understand the concept of pull up and pull down resistors. In this tutorial we show you how to include buttons in a project, by demonstrating a simple on/off function on an LED.

If you want to follow along at home, you can order the Arduino Kit we are using HERE.

This is the code we used in this project to switch the LED on and off.

 

9-Axis IMU LESSON 4: Plotting Serial Data from Arduino with Control of Axis Scale

As this project continues it is very important for us to be able to quickly and easily plot data streaming from the sensor. The Arduino Serial Plotter has some real limitations, we recommend a simple “Serial Plotter” tool that can be downloaded. In this video we take you step by step through the download and installation process, and then an overview of how to use the tool.

Arduino Tutorial 26: More Fun with Photo Resistors

In this lesson we create an audible signal where the tone of the signal is proportional to the brightness of the light in the room. We use a photoresistor to measure the light in the room, and then use a passive buzzer to create the audible signal. The video shows you how to hook everything up, and the code we use is below. Your code might be a little different, as the math will depend on the light values where you are.

If you want to follow along at home, you can order the Arduino Kit we are using HERE. The nice digital voltmeter used in the lesson is available HERE.

9-Axis IMU LESSON 3: Understanding How Accelerometers Work

Accelerometer
This photo shows a conceptual schematic of how an accelerometer works.

In this lesson we describe how the acceleromters on chips like the Adafruit BNO055 work. They work based on microscopic masses suspended on springs on the chip. As the chip moves, the suspended masses respond to the motion, and the gaps between the suspended masses and the substrate changes. The chips detect these changes in position by monitoring the capacitance between the suspended mass and the substrate, or between the suspended masses and carefully designed interdigitated fingers between the mass and the substrate. C=eA/d, e is the dielectric constant of the material, A is the area of the capacitor, and d is the gap between the two capacitor plates. Changes in measured capacitance come from either a change in A or a change in d. Both d and A change in response to motion, so by monitoring the capacitance of the suspended mass, acceleration can be inferred. The video below explains clearly how this works.

Code for Getting Raw Acceleration Data from the BNO055 9-axis Inertial Measurement Sensor.

The code below is for demo purposes only, and should not be used in any real applications. It just demonstrates how to work with this sensor in benchtop presentations.

Arduino Tutorial 25: Understanding Photoresistors and Photo Detectors


In this lesson we learn how to use photoresistors. A photoresistor is a semiconductor material. In the darkness, it has almost no free electrons, so its resistance is very high. When light shines on the device, electron hole pairs are created, and these electron hole pairs are free to conduct electricity. This lowers the resistance of the material. The brighter the light, the more electron hole pairs that are generated, and hence the lower the resistance. Hence, the resistance of these devices is inversely proportional to the brightness of the light. By hooking a photoresistor in series with a fixed resistor, the current will change as the resistance of the sensor changes. This leads to a measurable change in the voltage across the series resistor. Hence, by measuring this voltage, you get a signal that is proportional to the light. This can be read via an analog pin on the Arduino, and then the arduino can be programmed to do different things based on the brightness of the light. In this simple project we have a red LED and a green LED. If the light is on, the green LED is turned on. If the light is off, the red LED is on.

If you want to follow along at home, you can order the Arduino Kit we are using HERE.

The nice digital voltmeter used in the lesson is available HERE.

Below is the code we developed in this video lesson above.

 

Making The World a Better Place One High Tech Project at a Time. Enjoy!