Posts in Arduino
Infrared Thermometry Theory and Applications with Arduino and Python

In this tutorial, I will explore black body radiation, infrared detectors, and the relationship between temperature and emissivity - all with the intention of exploring how infrared (IR) detectors measure temperature from a distance. Arduino will be used, along with an MLX90614 IR thermometer, and a thermocouple for true-temperature approximation of each object. Planck’s discovery of energy quanta and their relationship to thermodynamics is the basis for radiation detectors and infrared temperature sensors. We will use Planck’s law to derive a usable equation that can relate the radiation measured by an infrared sensor to the temperature of a radiative object.

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MATLAB Datalogger with Arduino

In this tutorial, MATLAB is introduced as an interface for data acquisition with an Arduino board. The Arduino, in this particular case, will communicate with a Windows computer via the serial port and send data from an Arduino-compatible sensor, which will subsequently be read by MATLAB through its serial communication library. Serial communication from hardware to MATLAB is very simple and requires only a few lines of code. I will also introduce a real-time analysis and plotting routine to visualize the Arduino data as it arrives in real time. This particular method of data analysis and visualization in real time is incredibly useful for engineers interested in experimentation where microcontrollers and sensors may be used, along with complex data acquisition systems.

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Arduino Heart Rate Monitor Using MAX30102 and Pulse Oximetry

Pulse oximetry monitors the oxygen saturation in blood by measuring the magnitude of reflected red and infrared light [read more about pulse oximetry here and here]. Pulse oximeteters can also approximate heart rate by analyzing the time series response of the reflected red and infrared light . The MAX30102 pulse oximeter is an Arduino-compatible and inexpensive sensor that permits calculation of heart rate using the method described above. In this tutorial, the MAX30102 sensor will be introduced along with several in-depth analyses of the red and infrared reflection data that will be used to calculate parameters such as heart rate and oxygen saturation in blood.

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SAMD21 M0 Mini Arduino Board

In this tutorial, the SAMD21 M0 Mini is introduced, which is a variation of the Arduino Zero (SAMD21 48MHz). The SAMD21 board will be tested specifically in its speed and compatibility with several Arduino libraries. Particularly, the SAMD21 is the most powerful when harnessing its speed, but also in other areas such as analog to digital conversion. The SAMD21 core is a 32-bit microcontroller that will likely replace the traditional ATmega328 (8-bit microcontroller) over time. The SAMD21 core boasts 48MHz clock speeds in contrast to the 20MHz ATmega boards, while also being fully-compatible with many of the capabilities of the Arduino platform.

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WeMos D1 Mini ESP8266 Arduino WiFi Board

The WeMos D1 Mini is an inexpensive ESP8266-based WiFi board that is low-profile but just as powerful as any NodeMCU or ESP8266-based microcontroller. The D1 Mini is incredibly versatile because it is inexpensive, WiFi-enabled, and fully compatible with the Arduino platform. In this tutorial, the ESP8266 library and board manager will be introduced in order to get the D1 Mini acting as an Arduino board. Then, a simple web page will be introduced with the intention of harnessing the WiFi capabilities of the module. The D1 Mini will act as a web server, allowing any WiFi-connected device to interact with the board and control its pins wirelessly.

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Arduino Optical Fingerprint Sensor (AS608)

Optical fingerprint sensors take low-resolution snapshots of the tip of a finger and create arrays of identifiers that are then used to uniquely identify a given fingerprint. The AS608 is capable of storing up to 128 individual fingerprints. This tutorial will introduce the AS608 Arduino-compatible fingerprint sensor and how to validate and reject fingerprints based on the enrolled fingerprint information that will be given to the sensor. The fingerprint algorithm is handled by the AS608 and Arduino, so this tutorial will focus on implementation and putting the pieces together to make a working fingerprint sensor with Arduino.

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Arduino Interrupts with PIR Motion Sensor

The basics of Arduino’s hardware interrupt is explored through the use of a passive infrared (PIR) sensor. The passive infrared sensors used here operate at voltages from 2.7V - 5V and use very little energy when operating in the non-tripped state. The PIR sensor is ultimately tripped by an infrared source, typically human body heat (or another animal with similar radiative emission). When the PIR sensor is tripped it sends a HIGH signal to its OUT pin, which will be read by the Arduino’s interrupt pin (pin 2 or 3 on the Uno board). This process seems trivial, but when done correctly can save massive amounts of energy when dealing with battery-powered systems, as in home automation.

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Smartphone Arduino Weighing Scale with Load Cell and HX711

In this tutorial, I introduce an Arduino-based weighing scale that uses a load cell, analog-to-digital converter, and calibrated mass. I introduce calibration with known masses to create a powerful and accurate weighing system that can be used for highly accurate measurement purpose such as: chemistry, horticulture, cooking, and much more!

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Arduino Weighing Scale with Load Cell and HX711

In this tutorial, I introduce an Arduino-based weighing scale that uses a load cell, analog-to-digital converter, and calibrated mass. I introduce calibration with known masses to create a powerful and accurate weighing system that can be used for highly accurate measurement purpose such as: chemistry, horticulture, cooking, and much more!

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Arduino + VL53L1X Time of Flight Distance Measurement

Time of flight (ToF) is an approximation of the time it takes a traveling wave to come in contact with a surface and reflect back to the source. Time of flight has applications in automotive obstacle detection, resolving geographic surface composition, and computer vision and human gesture recognition. In the application here, the VL53L1X ToF sensor will be used to track the displacement of a ping pong ball falling down a tube. We can predict the acceleration and behavior of a falling ping pong ball by balancing the forces acting on the ball, and ultimately compare the theory to the actual displacement tracked by the time of flight sensor.

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Arduino SD Card Module Data Logger

This tutorial will explore the range of capabilities available to the Arduino SD library by using a real-world example of data logging. The SD library allows users to read/write, list files, create/remove files, and make/delete directories. Additionally, we will develop an algorithm that creates a new file every time the Arduino board is restarted, which will prevent overwriting of existing data records. The resulting data file will be in comma separated format and contain multiple data points, including a time stamp in milliseconds since the program started. Therefore, it is important to record the program start time. For very accurate time monitoring tasks, a real-time clock is recommended, however, for the experiments conducted here, relative time suffices.

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Arduino Uno R3 vs CH340

The CH340 Arduino board contains an ATmega328P-U-TH chip, which differs from the classic ATmega328P-PU in official Arduino Uno Rev3 boards. The CH340 is an inexpensive USB-to-Serial chip (datasheet here) that takes the place of the Rev3 board’s more expensive ATmega16U2. This creates issues when programming the Arduino board with certain operating systems (specifically Windows), however, for most Linux and Mac systems - there appears to be no issue. In this tutorial, I will explore the CH340 Arduino board to see whether there are differences in performance and power under different operating conditions. This will definitively answer whether the CH340 is a worthy alternative to the Rev3 or if it’s just a cheap imposter.

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Controlling LEDs with A Multiplexer and Arduino

A demultiplexer will be used to control 8 LEDs using just 3 digital pins on the Arduino board. This method of demultiplexing frees up pins on the Arduino, but also makes control of multiple LEDs easier by consolidating the power given to each LED. This will allow us to use LEDs without resistors. In general, a demultiplexer uses N boolean outputs to control 2N switches. In our case, the CD4051 multiplexer will be used as a demultiplexer using 3 digital pins and boolean logic to control 8 individual LEDs. Several skills will also be developed, specifically with regard to programming in the Arduino programming language. Pulse-width modulation (or brightening and dimming) of LEDs will be explored, as well as randomization of LED blinks, along with the general selection process for boolean switching with the demultiplexer.

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Loudspeaker Analysis and Experiments: Part II

Part II of the tutorial series on loudspeaker analysis and experiments. The majority of this entry focuses on finding Thiele-Small parameters to fully characterize an electrodynamic loudspeaker in free air.

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Arduino Pitot Tube Wind Speed and Airspeed Indicator - Theory and Experiments

The pitot tube is a device used to approximate the speed of vehicles traveling by air and water. An in-depth article on NASA's website is dedicated to pitot tubes (also called pitot-static tubes, Prandtl tubes), where it cites the primary application as airspeed indicator on aircraft. For more information on design and limitations of the instrument, I recommend perusing that page. For this tutorial, only the basic theory is explored using Bernoulli's equation and a practical application. An inexpensive pitot tube and a digital differential pressure sensor are used to measure pressure, which is converted to a digital signal using an Arduino board.

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Arduino Thermistor Theory, Calibration, and Experiment

Thermistor, whose name is derived from a combination of thermal and resistor, is a temperature sensing device that registers changes in internal resistance as a function of temperature. Thermistors are often chosen over thermocouples because they are more accurate, have a shorter response time, and are generally cheaper. For most applications, thermistors are the smart and easy selection for temperature sensing below 300 degrees Celsius. In our case, we will be using a Negative Temperature Coefficient (NTC) thermistor, where the resistance decreases as the temperature increases. NTC thermistors are most common in commercial products that operate in the tens of degrees like thermostats, toasters, and even 3-D printers. An NTC 3950 100k thermistor will be used, which is designed for 100kOhm resistance at 25 degrees Celsius. This tutorial will introduce methods for relating resistance to temperature by fitting factory calibration data. The performance of the thermistor will also be evaluated using an Arduino board and a simple Newton’s law of cooling experiment.

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NodeMCU Tutorial Series Part II: NodeMCU Server Control Over Local Area Network

This tutorial takes full advantage of the ESP8266 WiFi chip by serving a local webpage to control the general purpose input and output (GPIO) pins on a NodeMCU microcontroller. Some basic HTML and CSS programming methods will be utilized to create a stylish webpage that is both asynchronous (AJAX) and input-driven - this will give the user the ability to control the pins on the microcontroller. For the current example, an electromagnet and LED will be controlled using pulse width modulation (PWM) and simple high/low logic, respectively. The PWM control allows the user to change the voltage to the component, altering the magnetic field of the electromagnet. For the LED, the traditional digitalWrite() method will turn the LED on and off.

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NodeMCU Tutorial Series Part I: Arduino IDE and Blinking an LED

NodeMCU is a WiFi platform that integrates the ESP8266 system on chip hardware with the familiarities of open-source software. The NodeMCU is powerful because it endows users with the ability to create Internet of Things (IoT) projects at a relatively low cost with tools readily available and open to the maker community. NodeMCU is fully compatible with the Arduino IDE, which is the method for programming the board in this tutorial.

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iPhone Datalogger with Arduino Using The iOS Bluetooth App BLExAR

The BLExAR app will be used in conjunction with a CC2541 (HM-10, JDY-08, AT-09, SH-M08) Bluetooth module and an Arduino (ATmega328) board to create a simple data acquisition system. A DHT22 sensor will provide temperature and humidity data to the Arduino which will be recorded by an iOS device via the BLExAR app. This experiment is a real-world example of an Arduino application demonstrating data acquisition from a real sensor. This tutorial will allow users to solve their own engineering problems using the modern Arduino platform and wireless communication through the BLExAr app, which will ultimately expand the reach and compatibility of technology in the classical sciences through exploration and experimentation.

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4-Pin RGB LED Control Using iOS BLExAR App, HM-10 Bluetooth Module, and Arduino

Control an RGB LED using three PWM pins on an Arduino Uno board via Bluetooth communication. An RGB LED is a single casing with three cathode (or anode) pins and one anode (or cathode) pin. This results in a 4-pin LED. In this tutorial, I will be using an RGB LED with three anodes and one common cathode. This means that we can change the color of the LED to over 16.7 million different variations (assuming each anode produces a different luminosity for each voltage change of the Arduino PWM pin). This tutorial will help demonstrate the power of the BLExAR app, and the flexibility of an Arduino board under iOS Bluetooth control. In my case, I will be using an iPhone with the BLExAR app, but an iPad would suffice as well.

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