2.5A Bipolar Stepper Motor Driver using A3979


The tiny board designed using A3979 IC from ALLEGRO which is complete micro stepping driver with built in translator. The translator is the key to the easy implementation of the A3979. It allows the simple input of one pulse on the STEP pin to drive the motor one micro step, which can be either a full step, half, quarter, or sixteenth, depending on the setting of the MS1 and MS2 logic inputs. There are no phase-sequence tables, high-frequency control lines, or complex interfaces to program. The A3979 interface is an ideal fit for applications where a complex microprocessor is unavailable or is overburdened.


  • CN1 Motor Supply Input Up to 30V DC (35V Maximum)
  • Load 2.5A
  • Logic Supply 3.3V to 5V DC
  • CN3 Bipolar Stepper Motor Connections
  • CN2 Logic Supply 5V & Signal Inputs
  • J1-MS2 & J2-MS1 Micro-Stepping FULL, HALF, Quarter, Sixteenth
  • J3, J4 Option Replacement for PR1 Jumper Type Current Setting
  • D1 Logic Power LED
  • REF (PR1) Current Adjust 0-2V

2.5A Bipolar Stepper Motor Driver using A3979 – [Link]

4 Channel Large Current Relay Board


4-Channel Relay Board is a simple and convenient way to interface 4 relays for switching application in your project. The project has large Relay which can switch current up to 20Amps.


  • Input supply 12 VDC @ 360 mA
  • Output four SPDT Relay
  • Relay specification 20 A @ 230 VAC NC/30A NO
  • Trigger level 2 ~ 5 VDC
  • Box Header connector for connection of trigger signal
  • LED on each channel indicates relay status
  • Power-On LED indicator
  • Screw terminal connector for easy relay output and power in connection
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 65 mm x 116 mm

4 Channel Large Current Relay Board – [Link]


DIY Home Energy Meter

A new tutorial by The DIY Life is for building a home energy meter that provides information about power consumption and cost estimates for the month.

Using Arduino and some other components you can build your own energy meter that measure the supply current to your home through a CT (current transformer), current, power, maximum power and kilowatt hours consumed. The cost of electricity used to date can be added and displayed easily.


Electronics you need to build this project:

  • Arduino Uno
  • LCD Shield / LCD Screen
  • CT – Talema AC1030
  • 56Ω Burden Resistor
  • 10µF Capacitor
  • 2 x 100K Divider Resistors

If you are not familiar with Arduino or LCDs you can check these articles by The DIY Life to learn more: getting started with Arduino, connect an LCD screen

First you have to build the current sensor by connecting the CT to the Arduino and setting a right voltage reference due to the Arduino 0-5V input range. As shown below, this is the way you should connect the CT to the Arduino.


This code should be uploaded to your Arduino to run the project. It already has a scaling factor that can be adjusted due to the components you choose in your circuit.If you don’t want to use or don’t have an LCD screen, you can also modify the sketch to output to the Arduino IDE’s serial window as described in this code.

For more information on how to choose different components, how to calibrate them, and to learn more details about wiring and coding, you should check this tutorial out.

The first number displayed is the instantaneous current followed by the instantaneous power. On the bottom line, the kilowatt hours used since reset and then the maximum recorded power since reset. Check the meter in action:

Arduino Installing and Using Libraries


runtimeprojects.com has a tutorial on how to install and use Arduino libraries.

Libraries are an essential part in the Arduino world. They are what makes Arduino so easy to use. Libraries are written to encapsulate complex functions and expose them as simple function calls to the user. For example to switch a pixel on and off in an LED monitor. This is relatively very complex but, fortunately some folks at Adafruit created a library that enables us to handle an LEd monitor with simple functions like, draw lines, text, circles, rectangles, etc… Normally these libraries include a readme file with some explanations about the various functions, and examples of how to use the library.

Arduino Installing and Using Libraries – [Link]

ESP8266 sending data to Google spreadsheets

Although there are so many cloud IoT platforms (ThingSpeak, thinger.io, TESPA.io, Xively, … ) available in the market, each offering APIs and tools to allow the Arduino and ESP8266 users to directly upload their sensor readings online for real-time visualization and global access, Google Drive is still my favorite choice for posting sensor data online as it is more approachable. If you are a regular user of Google Drive, you would find this tutorial from Anir very useful too. It describes a method of connecting the ESP8266 device directly to a Google sheet for storing the sensor data without using any third party service, like pushingbox that most other Arduino users have used for fulfilling Google’s http requirements and handling the URL redirection. This tutorial explains how you can make the task much simpler by using a recently published HTTPSRedirect Arduino library by Sujay Phadke that allows the ESP8266 to self-handle the redirect and https GET requests. The tutorial uses a NodeMCU board and a soil moisture sensor as input for demonstration. The sensor data are directly posted to a spreadsheet on Google Drive.

ESP8266 connecting to Google spreadsheets for data logging
ESP8266 connecting to Google spreadsheets for data logging

The way it works is you need to setup a Google Apps Script to access a spreadsheet in your Google Drive. The script have access to the spreadsheet via its document sharing key, which is unique and can be found on the URL of the sheet. In order to remotely run the Google Script without exposing your Google credentials, you need to publish it as a Web App URL. The ESP8266 can then send data to the spreadsheet using the same Web App URL with actual sensor data appended to it. Because Google requires you to send any GET request over an Web App URL using https (more secured than http), and then redirect your request to another URL location, the HTTPSRedirect Arduino library by Sujay Phadke is the key to handle this smoothly. Otherwise, you would need to use a third party online service to accomplish the same. The tutorial also describes how to configure the Google spreadsheet for receiving the soil moisture data in correct cells and uses some built-in chart features to display the time series in real time.

For more info, visit the article page.

DIY Pixel Art Frame Using Raspberry Pi Zero

Have you ever wanted to get an interesting art frame? That can display and flip photos, scroll text, show the weather or display social media notifications?

Frederick Vandenbosch’s new tutorial is for building an art frame using 32×32 LED matrix and Raspberry Pi Zero.


Electronics used in this project

You can watch a detailed step-by-step tutorial for assembling the frame in this video:

You can use the Adafruit RGB Matrix HAT like the tutorial to control the matrix and to make wiring simpler. But it is not mandatory, you can also wire the LED matrix directly to Pi’s GPIO. A USB Wifi adapter or dongle plugs into one of your desktop or laptop’s USB ports, allowing you to connect to a wireless network in the home, office, or a public place. You can use this connection to access shared files, devices, and documents, or to connect to the Internet. To connect this dongle with your Pi Zero you need a OTG USB cable. Connecting this dongle with your projects will open up for you doors of innovation, and that what made this frame cool!

The wiring is as described in this picture.


Frederick used Raspbian Jessie “lite edition” for his Zero since the application is time-critical. Because it has more improvements, he preferred using Henner Zeller’s rpi-rgb-led-matrix library instead of the regular Adafruit library – which lately seemed an old version of the same series. He wrote a code to display and scroll ppm images, you can check it out here.

You can also use Raspberry Pi 3 in order to build this project, no need to change anything in software, and no need for the Wifi dongle since you can use the onboard Wifi. Things can be displayed on the matrix are unlimited. Since you have it connected with internet, this project could be your next IoT hack!

More details about this project and other amazing tutorials can be found at Frederick website.

Temperature sensors accurate to -40°C


by Denis Meyer @ elektormagazine.com:

With a local (on chip) precision of ±1°C over a range of temperature from –40°C to +65°C, and a remote (up to 3 external sensors) precision of ±1°C extended up to +125°C, the MCP990X digital temperature sensor offers an economic and flexible solution for external of industrial environments.

Temperature sensors accurate to -40°C – [Link]

A health patch a day keeps the doctor away


Belgian Imec and its subsidiary Holst Centre have developed a health patch which tracks physical and cardiac activity while monitoring bioelectrical impedance. The technology is up for licensing. by Jan Buiting @ elektormagazine.com

The health industry has recognized the challenges and solutions, with analysts predicting that the value of the global mobile health market is expected to more than triple in the next few years, from $19.2 billion in 2016 to $58.8 billion by 2020.

A health patch a day keeps the doctor away – [Link]

Ambient light sensor for heart rate sensing in wearables


Everlight (New Taipei City, Taiwan) has introduced an ambient light sensor that operates at 550nm with a very low signal calculation failure rate and a high current efficiency. An anticipated application for this device is heart rate signal detection in wearable electronics for the health and fitness sector. by Graham Prophet @ edn-europe.com:

Based on the principle of PPG (photoplethysmogram), the heart rate signal is calculated according to the current changes in transmission and reflection between a green light LED and the sensor to detect the systolic and diastolic blood vessel rythym. With a large detection area of 8.1mm ², improved signal strength is available from the ALS-PD50-42C. The larger sensing area can also improve the capabilities in instances when there are signal interferences caused by people’s skin colour, tattoos and hair on the skin.

Ambient light sensor for heart rate sensing in wearables – [Link]

Chemical Wireless Communication Without Electronics

Researchers at Stanford University have just invented a revolutionary way of communication. They are replacing the conventional way of wiring, wireless, radio and Bluetooth connectivity using chemicals that can be found in every house.


Nariman Farsad, now a postdoctoral fellow at Stanford, had built the first ever experimental chemical texting system in York University, which used vodka to send its messages.

While making research in the lab of Andrea Goldsmith, professor of electrical engineering, he and his fellow researchers have built a machine that sends messages using common chemicals. With the use of vinegar and glass cleaner, Farsad overcomes some hurdles he faced while sending data using vodka. In his vodka messaging machine, the signal would build up to the point that the receiving end was too saturated with vodka to receive more messages. Instead, easy to obtain chemicals like vinegar and glass cleaner could do better and plus these two specific liquids can cancel each other out at the receiving end of the system.

This system is extracting one and zero bits out of liquid since it sends pulses of acid (vinegar) or base (glass cleaner). After typing the message in a small computer, it will be send to a machine that pumps out the corresponding “bits” of chemicals, which travel through plastic tubes to a small container with a pH sensor. Changes in pH are then transmitted to a computer that deciphers the encoded message.

While working in Wireless Systems Laboratory, Goldsmith had faced a lot of challenges in her career in wireless communication and worked hard to overcome them, but now dealing with chemicals will be a new adventure for her and her research group without any previous best practices.

“Every problem that we’ve addressed in traditional wireless communications over the last three or four decades is really different now because it’s a different mode of communicating,” Goldsmith said. “As so, it opens up all of these new ways of thinking about the optimal way to design this type of communication system.”

Most of nanotechnology solutions that are out there are small in size, need power plus some wiring for connectivity, or depend on high frequency signals to operate, what would be harmful for body functions. This new chemical technology can be widely used in body-related sensors since chemical-based data exchange could be self-powered, traveling throughout the body harmlessly and can not be detected by outside devices.

Goldsmith and Farsad are now working in two directions, improving the current chemical texting system, and collaborating with two bioengineering groups at Stanford to make human body-friendly chemical messaging a reality.

This technology can open up new avenues in communication protocols replacing the base unit, the electricity, with chemicals.

You can read more about this brand-new way of communication at Stanford University website, and you can learn more in this video

This work is funded by the Natural Sciences and Engineering Research Council of Canada (NSERC) Postdoctoral Fellowship and by the National Science Foundation Center for the Science of Information.