Tag Archives: Mega

Homemade Pirani vacuum gauge controller with Arduino

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In theory, a Pirani gauge is a very simple device for measuring the pressure of a gas within a container, as it consists of a heated metal wire that loses heat as the pressure increases internally. With this value now known, the electrical resistance can be measured and used to determine the precise pressure of a given gas. And although the sensors themselves are relatively inexpensive, the controllers they are often connected to can have a very high price, which is why YouTuber Advanced Tinkering decided to create his own digital readout

The display uses an Arduino Mega to take in data from the sensor, convert it to a pressure level, and send it to a pair of LCDs. First, the Pirani gauge’s analog value is read with an ADS1115 ADC, which has 16 bits of resolution, and from there the value is converted to pressure using the calibration constant for air and a unit coefficient. The Mega then writes this information to the unit’s 16×2 character LCD module and plots points along a graph shown on a 3.5” TFT screen. Additionally, pressure data is sent via USB to a host machine where it can be read by an external program such as the Arduino Serial Plotter tool.

This DIY controller is a great showcase of how one can build their own scientific equipment for far cheaper than is otherwise available. To see more about this project, watch Advanced Tinkering’s video below!

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Test and diagnose your USB cables with this Arduino device

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USB cables come in a variety of shapes and sizes, with a different of internal connections that may be unknown to the user. For an easy way to figure out these connections, and to diagnose if the cable itself is faulty, TechKiwiGadgets has come up the Arduino Cable Tracer.

This device features an Arduino Mega board inside a 3D-printed enclosure, with IO pins connected to USB-A, USB-C, Micro-B, and Mini-B ports. It scans these ports to determine the configuration and lets the user know exactly how the cable is wired via a 2.8” TFT screen on top.

Code and build info can be found here if you’d like to make your own Arduino Cable Tracer.

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Dual Screen Apollo DSKY simulates the Apollo Guidance Computer

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NASA’s history if full of fascinating facts and trivia. For example, the Apollo Guidance Computer, which handled navigation and control for both the Apollo Command Module and the Apollo Lunar Module, ran with less RAM and processing power than a TI-83 graphing calculator. But reading that fact isn’t the same as actually experiencing the Apollo Guidance Computer for yourself. That’s why a maker used three Arduino boards to create a simulator.

The actual Apollo Guidance Computer sat inside of a protective metal enclosure that is rather boring, but the DSKY (Display and Keyboard) interface, which acted like a terminal, had a very distinctive design. It had 19 buttons, including a numerical pad, situated below two displays. The left display had a several indicator lights, similar to your car’s dashboard, to show the statuses and warnings. The right display had numerical readouts for the program number, verb, and noun, as well as data and a computer activity status light.

The Dual Screen Apollo DSKY simulator replicates all of that behavior when connected to a modern computer, which acts as the Apollo Guidance Computer. It has a couple 2.8″ 240 x 320 pixel LCD screens that mimic the DSKY’s displays. Below those are the same 19 buttons as the real DSKY. A pair of Arduino Nano boards control the two LCDs, while an Arduino Mega handles the keyboard. The Mega also appears as a virtual serial port when plugged into a computer. When MoonJS simulation software is running on the computer, the DSKY functions like the real deal.

If you want to get your hands on this cool little piece of Apollo history, it is currently for sale on Tindie.

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This archery robot always hits the target

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Both archery and robotics are extremely fun, but what happens when you combine the two? In Kamal Carter’s case, he constructed his own autonomous robotic archery system that can not only acquire and aim at targets, but even draw back the bow and fire an arrow all on its own.

The project features an Intel RealSense Depth Camera at its heart to acquire targets by looking for abnormally bright colors and to compute its distance away from them. This information is then fed to an Arduino Mega that uses some simple physics to determine where exactly the bow should be aimed via a pair of stepper motors. Once the target has been dialed in, another stepper pulls back the bow while a servo releases the string’s tension, thus firing the arrow. 

Carter has shared a video where he demonstrated the effectiveness of his autonomous archery system — and it’s impressive. The robot was able to recognize the apple on his head (just like in Robin Hood), tilt the bow up slightly, and then fire, which ended up knocking the apple off with minor collateral damage. 

You can read more about how Carter built this robotic archer by viewing his write-up over on Hackaday.io

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DIY Perseverance rover replica looks and moves like NASA’s

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Merely looking at the latest Mars rover, Perseverance, will make almost any nerd giddy with excitement over the amount of cool tech that’s crammed into the vehicle before it gets shot into space. This feeling is what probably inspired Dejan of How to Mechatronics to create his own scaled-down version of the interplanetary vehicle, but not only would it look great, his DIY rover would also be able to drive and show what it’s “seeing” to the operator. 

After designing a CAD model in Solidworks, Dejan got to work printing out the myriad of pieces required. The frame and structure of the rover is comprised of aluminum T-slot extrusions and tubes, while the rest is built from 3D-printed plastic. Each wheel was made to resemble the ones that are on the actual rover, and they are each driven by their own independent DC motor. Additionally, the four outer wheels are steered by separate servo modules. At the heart of the project is an Arduino Mega, which handles the DC motor drivers, servos, and the A4988 stepper driver that pans the camera horizontally. 

The rover’s driver has the ability to don a VR headset or just use their phone to view the output of its onboard FPV camera, which is pretty cool when trying to recreate what Perseverance does. More details about the project can be found here and seen in the video below where Dejan details how he built the scale rover and what all it can do.

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James Bruton’s robot uses three ball-shaped wheels to move in any direction

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Wheeled robots normally have wheels that move in a single axis and steer by using either differential speeds or by pivoting some kind of guide wheel. However, this leads to some drawbacks, the most obvious being an inability to move in really tight spaces. When presented with this challenge, YouTuber James Bruton came up with a great design for a highly mobile robot platform that employs a novel setup to move in any direction. Inspired by the work of researchers at Osaka University in Japan, the omni wheel uses a single drive shaft to spin, yet nearly every surface has a way to move along the ground. 

After designing his robot in Fusion 360 and 3D printing each part, Bruton assembled the wheels and added a pulley to each drive shaft which could be spun by a motor sitting directly above. An Arduino Mega is tasked with controlling each of the three BTS7960 motor drivers and it receives commands via an nRF24L01 radio module. All of the drive components are powered by a single 3-cell LiPo battery pack, while the main board is supplied current by a USB battery bank. 

By spinning certain wheels at the correct speed, straight line motion can be produced, as shown in the video below. Bruton tested his robot by driving over carpet, tile, aluminum extrusions, and even a plastic lid, which did very well across everything except the lid. This robot has countless potential uses, such as a garbage collection device for around the house. 

Code and design files for the project are available on GitHub.

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