Easier UART to 1-Wire Interface

The 1-Wire protocol is usually found in temperature sensors, but you’ll also find it in chips ranging from load sensors, a battery sensor and LED driver that is oddly yet officially called a ‘gas gauge’, and iButtons. It’s a protocol that has its niche, and there are a few interesting application notes for implementing the 1-wire protocol with a UART. Application notes are best practices, but [rawe] has figured out an even easier way to do this.

The standard way of reading 1-Wire sensors with a UART is to plop a pair of transistors and resistors on the Tx and Rx lines of the UART and connect them to the… one… wire on the 1-Wire device. [rawe]’s simplification of this is to get rid of the transistors and just plop a single 1N4148 diode in there.

This would of course be useless without the software to communicate with 1-Wire devices, and [rawe] has you covered there, too. There’s a small little command line tool that will talk to the usual 1-Wire temperature sensors. Both the circuit and the tool work with the most common USB to UART adapters.

The Network of 1-Wire Devices


[jimmayhugh] is a homebrewer and has multiple fermentation chambers and storage coolers scattered around his home. Lucky him. Nevertheless, multiple ways of making and storing beer requires some way to tell the temperature of his coolers and fermenters. There aren’t many temperature controllers that will monitor more than two digital thermometers or thermocouples, so he came up with his own. It’s called TeensyNet, and it’s able to monitor and control up to 36 1-wire devices and ties everything into his home network.

Everything in this system uses the 1-Wire protocol, a bus designed by Dallas Semiconductor that can connect devices with only two wires; data and ground. (To be a fly on the wall during that marketing meeting…) [jimmay] is using temperature sensors, digital switches, thermocouples, and even a graphic LCD with his 1-wire system, with everything controlled by a Teensy 3.1 and Ethernet module to push everything up to his network.

With everything connected to the network, [jimmay] can get on his personal TeensyNet webpage and check out the status of all the devices connected to any of his network controllers. This is something the engineers at Dallas probably never dreamed of, and it’s an interesting look at what the future of Home Automation will be, if not for a network connected relay.

Axis Glove That Controls a Robot


This homemade glove and gesture controlled rover was created by [electro18]. It can send temperature, battery level, and object distance to the LCD panel on the wrist. Instead of a typical joystick, this wireless system taps into an embedded accelerometer to maneuver the robot like magic.

The main chassis platform is made of clear acrylic and has additional acrylic strips fixed to the edges for additional strength. A LM35 temperature sensor is wired to the front that monitors the environments that the rover explores. An HC-SR04 Ultrasonic Rangefinder acts as the eyes of the machine. The photodiode is covered with an adaptation of a 6mm heat shrink tube to avoid false readings. Once hooked up and turned on, the robot can be controlled with the futuristic power glove consisting of two parts. An accelerometer strap and a display strap are the biggest parts. The project shows that it is relatively easy to make a system like this. Other items like quadcopters and tiny water boats could be controlled with a similar type of setup.

A video of the axis glove maneuvering the vehicle on a slope can be seen after the break:

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Modular Arduino Based Infrared Thermometer


[Brian] started out with a clear and concise goal, “allow a regular human to associate an audible tone with a temperature from an infrared contactless thermometer.” With his latest project, the ESPeri.IRBud, he has achieved this goal.

One of our favorite parts of [Brian’s] post is his BOM. Being able to easily see that the IR temperature sensor costs $26 at DigiKey is unbelievably helpful to readers. This specific sensor was chosen because others have successfully interfaced it with the Arduino. Not having to reinvent the wheel is good thing! For the build, [Brian] decided to hook up the IR temperature sensor to a re-purposed flexible iPhone headset wire. Having used headphone sockets to connect to the sensor and speakers, the actual device is quite modular. Hearing this thing in action is quite cool, it almost sounds like old-school GameBoy music! Check it out after the break.

Have you used an IR temperature sensor in one of your projects? Let us know.

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Temp-Sensitive Automatic Blinds


Any opportunity to shave a few bucks off your power bill is probably worth considering, especially if it’s a device like [Steve Hoefer’s] Mini Blind Minder. This little guy staves off (or welcomes) the sun by monitoring the room with a temperature sensor and checking against a setpoint. If the room is too warm or too cool, the top-mounted servo will spin the wand and close or open the blinds, respectively.

[Steve] started by building a homemade Arduino shield from some perfboard to which he added a handful of discrete components: some current-limiting resistors for the RGB LED indicator light and a 10k trim pot for fine-tuning the temp sensor. Although this build forgoes an LCD readout to display precise information, it does provide feedback by stepping the RGB LED’s color through a spectrum of blue to red to indicate how the current room temperature compares to your setpoint. The two momentary pushbuttons beneath the light allow the user to adjust the setpoint up or down.

See the video below for a detailed guide to building your own, and take a look at a similar automatic blinds build from earlier this year that opens and closes in response to ambient light.

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Crystal oven temperature sensor reads 0.01F resolution


[Scott Harden] continues his work on a high precision crystal oven. Being able to set a precise temperature depends on the ability to measure temperature with precision as well. That’s where this circuit comes in. It’s based around an LM335 linear temperature sensor. He’s designed support circuitry that can read temperature with hundredth-of-a-degree resolution.

Reading the sensor directly with an AVR microcontroller’s Analog-to-Digital Converter (ADC) will only yield about 1-2 degrees of range. He approached the problem by amplifying the output of the sensor to target a specific range. For the demonstration he adjusts the swing from 0-5V to correspond to a room temperature to body temperature range.

Of course he’s using analog circuitry to make this happen. But before our digital-only readers click away you should view his video explanation. This exhibits the base functionality of OpAmps. And we think [Scott] did a great job of presenting the concepts by providing a clear and readable schematic and explaining each part slowly and completely.

So what’s this crystal oven we mentioned? It’s a radio project that goes back several years.

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Roomba becomes data center robot


Running a data center takes a lot of work, and even making sure the ambient temperature for hundreds of boxes is in the proper range is an arduous task. When faced with the prospect of installing hundreds of temperature sensors in an EMC data center, [Vivek] had a better idea: put just a few sensors on a robot and drive around the racks. With the right software, it’s a breeze to automate the process and build a near real-time temperature monitoring solution for a huge data center.

The data center robot is based on a iRobot Create, basically a Roomba without a vacuum. Attached to the robot is a netbook, Arduino, and a PVC mast housing three temperature sensors and a USB webcam.

Using the floor of the data center for navigation, the robot canvasses the racks sending temperature data back to a server via WiFi. From there, the temperatures can be graphed to make sure the racks aren’t too hot or too cold.

You can check out a video of the robot in action after the break.

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