Tag Archives: ATmega2560 MCU

An open-source PLC to control the Internet of Things

Controllino is the first software open-source, Arduino-compatible PLC. 

Designed by the SG-Tronic team, the Controllino is an open-source programmable logic controller (PLC) built around Atmel’s ATmega328 and ATmega2560 microcontrollers (MCUs). Recently funded on Kickstarter, the Arduino-compatible PLC allows Makers to produce and control their next Internet of Things project, ranging from industrial to home automation applications.


“When I was at electronic school, I would have loved Arduino. But back then, microcontroller programming wasn’t that easy. When I became aware of Arduino, I thought… What a great idea for young people and those who are not hardcore microcontroller programmers,” creator Marco Riedesser explained. “The only problem with Arduino is [that] when you don’t really know so much about electronic hardware, driving more than a LED can become difficult. And using an Arduino board in a professional project or even a product that you want to sell is quasi impossible if you want to get certification.”

Now fully UL and CE-certified, Makers can begin creating and actually shipping gadgets such as drones, home appliances, or any other electronic project that comes to mind. The Atmel powered PLC is currently being presented in three models: Mini, Maxi and Mega.

“I had to repair the coffee machine for my brother-in-law. I thought it would be easy to use Arduino but there was nothing on the market that could handle switching high voltage and high current. So I thought I had to come forward with a product,” Riedesser revealed to TechCrunch earlier this year.


All Controllino PLCs are equipped with an internal RTC using SPI, which can be switched on/off and allow for the use of SPI for other purposes via pin header. With built-in processor contact, Makers have a direct link to a number of boards (like Arduino). All pins are also 4000V ESD protected. What’s more, both the Controllino Maxi and Mega let users select between internal RTC and Ethernet using SPI, as well as turn it off so they can use the SPI for other purposes via pin header.

The versatile device works in altitudes up to 2,000m above sea level, in temperatures ranging between 5°C to 55°C, and in maximum relative humidity 80% for temperatures up to 31°C decreasing linearly to 50% relative humidity at 55°C. Each Controllino features an automatic input voltage range selection. This internal function changes voltage dividers ratio on the processor input, and enables the use of one input for analog and digital and for 12V or 24V input voltage range without user action. In addition, the Controllino’s main supply voltage fluctuates up to ±10% of the nominal voltage


Key Mini specs:

  • MCU: ATmega328 MCU
  • RTC
  • Clock speed: 16 MHz
  • 1x RS232 interface
  • 1x SPI interface
  • 6x relay outputs (230V/6A)
  • 8x digital outputs (2A @12V or 24V)
  • 8x analog/digital inputs
  • 10A input current max


Key Maxi specs:

  • MCU: ATmega2560
  • RTC
  • Clock speed: 16 MHz
  • Ethernet connection
  • 2x RS232 interface
  • 1x RS485 interface
  • 1x I2C interface
  • 1x SPI interface
  • 10x relay outputs (230V/6A)
  • 12x digital outputs ( 2A @12V or 24V)
  • 12x analog/digital inputs
  • 20A input current max


Key Mega specs:

  • MCU: ATmega2560 MCU
  • RTC
  • Clock speed: 16 MHz
  • Ethernet connection
  • 2x RS232 interface
  • 1x RS485 interface
  • 1x I2C interface
  • 1x SPI interface
  • 16x relay outputs (230V/6A)
  • 24x analog/digital inputs
  • 12x digital outputs – high side switch (2A @12V or 24V)
  • 12x digital outputs – half-bridge (2A @12V or 24V)
  • 20A input current max

Interested in learning more? You can check out Controllino’s official page here. Those wishing to purchase the Mini, Maxi and Mega can now do so for € 119.00, € 199.00 and € 269.00, respectively.

Harpa is an origami night light

Harpa – which recently surfaced on the official Arduino blog – is a large hand crafted elephant lamp shade with Wifi controlled RGB LEDs, microphone, speaker and a custom designed iPad application to teach children about color.

Originally conceived as a small paper origami elephant with blinking LEDs, the model was designed in Blender and 3D printed as a solid wireframe using the Shapeways service.

“The idea with the wireframe was to hand sew all the faces onto the model, that way I could try different materials as well as save money on the 3D print (printing filled surface faces would cost thousands at that size),” Harpa creator Trent Brooks explained in a recent blog post.

“The electronics are driven by an [Atmel-based] Arduino Mega 2560 board (ATmega2560 MCU) with Ethernet shield for network control. Connected to the board is a 50cm 5V RGB addressable LED strip with 30 LEDs, a 3.3V microphone module for sound detection and an 8ohm speaker for playing back generated ‘white-noise’ audio. Total cost for the all the electronics was less than $100.”

According to Brooks, the custom iPad application allows children to learn about color by selecting from various presets. Essentially, the primary interface displays a grid of colored elephant heads. When one is selected, the name of the color is pronounced, while the main night light changes color.

“There is a hidden control panel in the iPad app which allows me to change some of the more advanced features. For example, I can switch the ‘white-noise’ speaker on,” he added.

“[Plus] I can switch on audio reactive mode which uses the microphone to detect variations in sound level to change the LED colors (great when playing music, not so much for a sleeping baby); I can also change the number of LED’s, brightness, saturation and have them auto cross fade into different colors.”

Interested in learning more about Harpa? You can check out the project’s official page here.

Creating a 3D printer for under $100

Tarkun Gelstronic has created a 3D printer for under $100.

Aptly dubbed the Poor Man’s 3D Printer, the device includes a heat bed and is capable of printing with multiple materials.

Key components purchased by Gelstronic include:

As 3DPrint’s Monica Aderholt notes, one of the major ways Gelstronic was able to keep the price so low was by recycling old computer and printer parts.

“Tarkun obtained four stepper motors from old DVD and Blu-ray drives, a power supply from an old PC, a NEMA 17-like stepper motor from an old printer and a modified gear from an old Hewlett Packard printer, which was used for the bowden extruder,” Aderholt explains.

“Of course, he had to use a bunch of screws, washers, nuts, wires, etc., but these were things that he and a lot of people would have lying around in their garages. For the frame of the printer, he did cheat slightly, and used some aluminum sheet metal that he had lying around. However, he points out that this could be replaced with wood.”

All told, Tarken ended up spending only 49 Euros, or approximately $67 on all purchased items, which isn’t bad for a 3D printer that offers the following features:

  • Fused deposition modeling ABS/PLA
  • Heat bed
  • Use of open source firmware – a modified version of Tonokip
  • Free host software, Repetier-Host
  • Bowden-extruder
  • Max. build size 40mm x 40mm x 40mm
  • Resolution 0.08mm

Interested in learning more? You can check out the project’s Instructables page here.

Video: Arduino Mega drives single-wheel Jackal

Nick Thatcher has debuted the Jackal, a slick one-wheeled self balancing vehicle (unicycle) equipped with a single 19-inch motorcycle wheel.

The Jackal – powered by a 24v 450w geared unite motor – is controlled with the help of an Atmel-based Arduino Mega (ATmega2560 MCU) that maintains the cycle’s balance.

“The Arduino Mega REV3 takes the data from the inertial measurement unit IMU (gyro), does some number crunching and then spits out PWM signals in the direction of the motor controller,” Thatcher explained.

Aside from the Atmel-based Arduino Mega, key project components include:

  • IMU (gyro)
  • SyRen 50 motor controller
  • Two 12v 12ah lead acid batteries (slated for upgrade)
  • PVC
  • Chain drive

The Jackal is capable of achieving a top speed of 20mph, with enough torque to climb all but the steepest of all hills.

According to Thatcher, the Jackal builds on a previous project dubbed “The Raptor,” adding speed, style and a proper wheel.

Interested in learning more? You can check out The Jackal’s official page here.

ATmega168 MCU powers energy-saving thermostat

Earlier this month, Bits & Pieces took a closer look at a smart thermostat in the Netherlands powered by an Arduino Mega 2560 (ATmega2560 MCU), as well as a three-zone thermostat built around an Atmel-based Arduino Uno (ATmega328).

Today, we’re going to get up close and personal with a thermostat equipped with a stand-alone Atmel ATmega168 AVR micrcontroller that was built to regulate Andrian’s boiler.

“After a few minutes, the [boiler] warms the water enough so that the water temp exceeds the thermostat limit. The thermostat changes state and drives an electric valve to move the water from the boiler to the radiators. The electric valve is slow and takes a few minutes to make a full turn,” Andrian wrote in a recent blog post.

“While the water is moving from the boiler to the radiators, circularly cool water is coming back from the radiators. Τhe water temp in the boiler is getting cooler and after a few minutes falls under the thermostat’s limit. The thermostat changes state and stops the valve from driving the water to radiators. This happens again and again until [all the] water in the radiators is warm. ”

To prevent this issue – opening and closing the electric valve in minimal increments – Andrian designed a thermostat capable of delaying the sample points. More specifically, it monitors the boiler temp, driving the electric valve only when the overall water temp exceeds the thermostat limit. Subsequently, the device waits half an hour or more before once again checking the water temperature.

Key project specs include:


One LM7805 regulator and two capacitors (simple power supply design)
Rotary/push-button switch (menu selection and configuration)
Two relays driving external electric valves
  • HD4780 LCD display

“The main MCU is the [Atmel] 8-bit AVR ATmega168, with a buzzer [alerting] the user for a button press or a limit exceeded,” Andrian explained.


“[Meanwhile], two LM35 temp sensors one internal and one external measure the ambient and pipe – boiler temp. You [will] also notice a 32.768Khz crystal, used to implement a real time clock which [tracks] real time delays.”

Interested in learning more about Andrian’s AVR-thermostat? You can check out the project’s official page here.