Interfacing OLED Display with Android Phone

Most of us would be familiar with the 16×2 Dot matrix LCD display that is used in many projects to display some information to the user. But these LCD displays have a lot of limitation in what they can do. In this tutorial, we will use OLED to display some basic information from the Android smartphone like Time, date, network strength and battery status. This project provides a basic idea and framework to build an Arduino based SmartWatch and can be further extended to display incoming calls, messages and many more on OLED display.

Here you can find the basic circuit diagram to interface the OLED with Android phone using a bluetooth module:

To check out the complete project with codes and required libraries for arduino, visit the link below:

https://circuitdigest.com/microcontroller-projects/build-an-arduino-smart-watch-by-interfacing-oled-display-with-android-phone

Basics of Stepper Motor

From a simple DVD player or printer in your home to a highly sophisticated CNC machine or Robotic Arm, Stepper motors are to be found almost everywhere. Its ability to make electronically controlled precise movements have made these motors find application in many felids like surveillance cameras, Hard disk, CNC machines, 3D Printers, Robotics, Assembly robots, Laser cutters and much more.

Image Source: Components101

Like all motors the stepper motors also have a stator and a rotor, but unlike a normal DC motor the stator consists of individual sets of coils. The number of coils will differ based on type of stepper motor, but for now just understand that in a stepper motor the rotor consists of metal poles and each pole will be attracted by a set of coil in the stator. The below diagram shows a stepper motor with 8 stator poles and 6 rotor poles.




If you take a look at the coils on the stator, they are arranged in terms of coil pairs, like A and A’ forms a pair B and B’ forms a pair and so on. So each of this coil pair’s form an electromagnet and they can be energised individually using a driver circuitry. When a coil gets energised it acts as a magnet and the rotor pole gets aligned to it, when the rotor rotates to adjust itself to align with the stator it is called as one step. Similarly by energising the coils in a sequence we can rotate the motor in small steps to make a complete rotation.

Source and read more: Stepper motor tutorial

Audio Amplifier Circuit Design Tutorials

Amplifiers are the backbone of Analog electronics. They are used vastly in the field of electronics industry. Amplifiers are used almost in all the audio related applications.  Power amplifier are designed to maximize the magnitude of the power of given input signal. In audio electronics, the operational amplifier increases the voltage of the signal, but unable to provide the current, which is required to drive a load.



Here I am sharing few tutorials to design audio amplifier circuits which delivers output in various ranges. Please click the links below and go through the tutorials which covers each amplifier in detail.

10W Audio Amplifier using Op-Amp 

25W Audio Amplifier Circuit

40W Audio Amplifier using TDA2040 

50W Amplifier Circuit using MOSFETs

100W Audio Amplifier using MOSFET 

Hope you liked the tutorials!

Getting Started with STM32 Microcontroller

Arduino would have been the first board for many hobbyists (including me) and engineers out there when they started with electronics. However, as we start building more and dig deep we would soon realise that Arduino is not industry ready and its 8-bit CPU with a ridiculously slow clock, it does not give you enough juice for your projects. Hopefully though, we have the new STM32F103C8T6 STM32 Development Boards (Blue Pill) in the market now which can easily outperform Arduino with its 32-bit CPU and ARM Cortex M3 architecture. Another honey pot here is that we can use the same old Arduino IDE to program our STM32 Boards. So in this tutorial, let us get started with the STM32 to know a bit of basics about this board and blink the on-board LED using the Arduino IDE. 

The STM32 board a.k.a Blue Pill is a Development board for the ARM Cortex M3 Microcontroller. It looks very much similar to the Arduino Nano but it packs in quite a punch. The Development board is shown below.

Working with STM32 development board is quite easy. You can check below the series of tutorials which covers basics as well as higher level tutorials in order of increasing difficulty.

• Getting Started with STM32 using Arduino IDE: Blinking LED
• Interfacing 16x2 LCD with STM32F103C8T6
• Programming STM32F103C8 Board using USB Port
• How to use ADC in STM32F103C8 - Measuring Analog Voltage
• Pulse width Modulation (PWM) in STM32F103C8: Controlling Speed of DC Fan
• Interfacing Bluetooth HC-05 with STM32F103C8 Blue Pill: Controlling LED
• Interfacing Stepper Motor with STM32F103C8

You can explore more STM32 tutorials and projects here: https://circuitdigest.com/stm32-projects-and-tutorials

Build An Arduino Based Self Balancing Robot!

After being inspired by RYNO motors and other self balancing scooters from Segway, I always wanted to build something similar. Thinking for while, I decided to build a Self Balancing Robot using Arduino. This way I would be able to grasp the underlying concept behind all these scooters and also learn how PID algorithm works.



When I started building this self balancing robot, I realized that this bot is a bit of a challenge to build. There are so many options to select from and hence the confusions start right form selecting the motors and remains till tuning PID values. And there are so many things to consider like type of battery, position of battery, wheel grip, type of motor driver, maintaining the CoG (Centre of gravity) and much more. But let me break it to you, once you build it you will agree that it’s not as hard as it sounds to be. So let’s face it, in this tutorial I will document my experience in building the self balancing robot. You might be an absolute beginner who is just getting started or might have landed up here after a long frustration of not getting your bot to work. This place aims to be your final destination.

Below is the video of the Self Balancing Robot working.


You can find the complete DIY instructions along with schematic diagram and codes, required to build this Self Balancing Robot in the following link: https://circuitdigest.com/microcontroller-projects/arduino-based-self-balancing-robot

PIC Microcontroller Communication Tutorials

In the vast system of embedded applications, no microcontroller can perform all the activities by itself and so it has to communicate to other devices to share information. There are many different types of communication protocols used by microcontrollers to share these information’s, but the most used ones are USART, IIC, SPI and CAN. Each communication protocol has its own advantage and disadvantage. To learn how to work with these communication protocols in PIC microcontroller, Below are few tutorials which provide the complete guide to use these communication protocols.

1. PIC Microcontroller I2C Communication


The term IIC stands for “Inter Integrated Circuits”. It is normally denoted as I2C or I squared C or even as 2-wire interface protocol (TWI) at some places but it all means the same. I2C is a synchronous communication protocol meaning, both the devices that are sharing the information must share a common clock signal. It has only two wires to share information out of which one is used for the cock signal and the other is used for sending and receiving data.
Click the link to learn more about PIC microcontroller I2C communication

2. PIC Microcontroller SPI communication


The term SPI stands for “Serial Peripheral Interface”. It is a common communication protocol that is used to send data between two microcontrollers or to read/write data from a sensor to a microcontroller. It is also used to communicate with SD cards, shift registers, Display controllers and much more. Know more about PIC SPI communication

3. PIC Microcontroller UART Communication


Here we have used PIC16F877A MCU, it has a module called “Addressable Universal Synchronous Asynchronous Receiver and Transmitter” shortly known as USART. USART is a two wire communication system in which the data flow serially. USART is also a full-duplex communication, means you can send and receive data at the same time which can be used to communicate with peripheral devices, such as CRT terminals and personal computers. Know more about PIC UART communication.

4. CAN Communication with PIC Microcontroller
Bring communication and connectivity in your embedded design to the next level with Microchip's Controller Area Network (CAN) bus solutions technology. Originally created for automotive applications, the CAN bus protocol is a high-speed, reliable communication protocol for applications requiring robust communications at bit rates reaching 8 Mbps. Incorporating the CAN bus protocol into your design is a low-cost, reliable way to function in a difficult electrical environment with a high degree of real-time capability. Learn more about CAN communication here.

5 Arduino Projects to Try for Intermediate DIYers

1. Battery Voltage Level Indicator on LED Bargraph

This Arduino battery voltage indicator indicates the status of the battery by glowing LEDs on a 10 Segment LED Bar Graph according to the battery voltage. It also shows your battery voltage on the LCD connected to the Arduino.

Find here the complete project

2. TVOC and CO2 Measurement using CCS811

For designing an air quality monitoring system we need durable and reliable air quality sensor. Although there are many Air Quality parameters but the most important are CO2 and TVOC. So for sensing CO2 and TVOC, we are using CCS811 Air Quality Sensor.

Find here the complete project 

3. Automatic Pet Feeder Project

This Arduino based Automatic Pet Feeder which can automatically serve food to your pet timely. It has a DS3231 RTC (Real Time Clock) Module, which used to set time and date on which your pet should be given food. So, by setting up the time according to your pet’s eating schedule, the device drop or fill the food bowl automatically.

Find here the complete project 

4. DIY Inclinometer

The MPU6050 is an IC 3-axis accelerometer and a 3-axis gyroscope combined into one unit. It also houses a temperature sensor and a DCM to perform a complex task. The MPU6050 is commonly used in building Drone and other remote robots like a self-balancing robot. In this project we will learn how to use the MPU6050 is built an Inclinometer or Spirit Leveller. As we know an inclinometer is used to check if a surface is perfectly leveled or not, they are available either as sprit bubble ones or as digital meters. In this project, we are going to build a Digital Inclinometer which can be monitored using an Android application. The reason for using a remote display like a mobile phone is that we can monitor the values from MPU6050 without having to look at the hardware, this would come very handy when the MPU6050 is placed on a drone or some other inaccessible locations.

Complete Project 

5. Alcohol Detector using Arduino

This Arduino Alcohol Detectorwill detect the alcohol level in breath and by using some calculations in code we can calculate the alcohol level in breath or blood and can trigger some alarm. 

Find here the complete project