When aiming for any Internet of Things (IoT) project, the first thing comes in mind is to choose a microcontroller. Microcontroller is the brain of the system. The whole system is controlled by microcontroller. Information sent by the sensors is processed, converted if required and then the output is being chosen accordingly by the microcontroller. There are a number of microcontrollers available. So we have to choose the correct microcontroller for our project to reduce price and increase performance. Here we will be discussing with some microcontrollers and some development boards which can be used in project. 1. ATMEL ATMEGA 8A Atmega 8A is a microcontroller from Atmel. The key features are – 1. 8 Kilobytes of in system programmable flash memory 2. 1 Kilobytes of Internal SRAM 3. 3 PWM Channels 4. 6 Channel ADC 5. 23 Programmable IO Pins 6. 512 bytes EEPROM So, Atmega 8 can be used where the program memory is less than 8 Kilobytes and there are fewer variables as the SRAM memory is only 1 Kilobyte. Pros: 1. Lightweight because there are only 28 pins and it comes in small PDIP package. 2. 23 Programmable IO Pins can handle a lot of sensors and outputs. 3. Low Cost Buy 4. Easy to program 5. 6 channel 10 bit ADC can handle six different analog sensors. Cons: 1. Only 1 KB of SRAM 2. There are only 3 PWM Channels 3. Any type of wireless communication must be added externally. 2. ATMEGA 328P Atmega 328p is a 8-bit low power microcontroller with 32k In-System Programmable flash in a 28 pin PDIP Package. Features — 1. 32 Kilobytes of in system programmable flash memory 2. 2 Kilobytes of Internal SRAM 3. 6 PWM Channels 4. 6 channel ADC 5. 23 IO Pins 6. 1 Kilobyte of EEPROM Pros: 1. 32 KB Flash Memory can handle bigger programs. 2. 6 PWM channels can be used for six different analog output machines. 3. 1KB of EEPROM can store a lot of data even when the power is off.. Cons: 1. Costly (Buy) 2. For wireless communication we have to add modules externally. 3. NODEMCU ESP8266 NodeMCU is an open-source firmware and development kit that helps you to prototype or builds IoT products. It includes firmware that runs on the ESP8266 Wi-Fi SoC from Espressif Systems. Features: 1. 4 Megabytes of in system programmable flash memory. 2. 128 Kilobytes of internal RAM 3. 802.11b/g/n HT40 WifiTranceiver 4. 10 Programmable GPIOs 5. Single ADC 6. 10 PWM Pins Above features of NodeMCU ESP 8266 shows that it is ideal for wifi based projects. Though there are some cons. Pros: 1. Wifi in-built 2. Current Consumption is as small as 80 mA during transmission and 20 uA during sleep. 3. All GPIOs are PWM enabled. 4. 4 Megabytes of program space can hold an extremely large program. Cons: 1. Only one ADC. For multiple sensors we have to use multiplexer. 2. The number of GPIOs is quite low. 4. ESP32 DEV BOARD Created by Express if Systems, ESP 32 is a low cost, low power system on chip series with wifi and bluetooth capabilities. Features: 1. ESP 32 is Dual Core 2. Wifi and Bluetooth built in 3. 4 MB of in system programmable flash memory 4. 512 KB SRAM 5. 34 GPIOs 6. 18 Channel ADC Pros: 1. 34 GPIOs can be connected with a lot of input and output devices. 2. 18 channel ADC makes it easier to connect with multiple analog sensors. 3. It has built in touch switches. 4. WiFi and Bluetooth two in one features make the communication easier. 5. ADC is 12 bit so, more accuracy. Cons: 1. High Price 2. More complex 3. Because it is more recent than esp 8266, not all software has been developed to take the most out of the ESP32 functionalities. 5. RASPBERRY PI 3 Raspberry pi 3 is a single board computer with LAN, wifi and bluetooth connectivity. Features: 1. Quad Core broadcam BCM 2837 64 bit ARMv8 Processor 2. Runs at 1.2 GHz 3. Four USB Ports 4. 26 IO 5. 4 PWM Pins 6. 1GB internal RAM 7. Wifiand bluetooth 8. Ethernet 9. 3.5mm Audio Jack Above features makes it possible to use this Raspberry Pi where a PC or a greater processing power is necessary. Pros: 1. Raspberry pi does not require the user to have extensive programming experience. 2. The Raspberry pi is perfect for adaptive technology: It is able to display images or play videos at 1080p hd resolution to building systems such as digital jukeboxes or prototyping embedded systems. 3. The product is energy efficient and provides a greener ethical alternative to small businesses. This small credit card sized product makes it easy to recycle and does not release as much carbon dioxide emissions into the environment, unlike big servers that require lots of energy and extensive cooling systems. 4. The product also gives you a lot of room to experiment and turn it into something else that is entirely different. The SD cards on the board can be easily switched, which allows you to change the functions of the device without spending a lot of time re-installing the software. Cons: 1. It does not replace your computer, since the Ethernet is only a 10/100 and the processor is not as fast, it is time consuming to download and install software and is unable to do any complex multitasking. 2. Not compatible with other operating systems such as Windows. 3. Heavy Cost There are various microcontrollers or brains for different uses. When making a project we have to choose the microcontroller wisely depending on the requirement like project cost, wireless communication, number of digital and analog sensor etc. We provide a variety of IoT devices like Automatic Pump Controller, Motion Sensing Light, Safety Devices like Fire Alarm, Smoke Alarm and many Industrial IoT Solutions. Contact us if you have such requirements in mind.