Reverse Engineering Wireless Temperature Probes

[bhunting] lives right up against the Rockies, and for a while he’s wanted to measure the temperature variations against the inside of his house against the temperature swings outside. The sensible way to do this would be to put a few wireless temperature-logging probes around the house, and log all that data with a computer. A temperature sensor, microcontroller, wireless module, battery, case, and miscellaneous parts meant each node in the sensor grid would cost about $10. The other day, [bhunting] came across the exact same thing in the clearance bin of Walmart – $10 for a wireless temperature sensor, and the only thing he would have to do is reverse engineer the protocol.

These wireless temperature sensors are exactly what you would expect for a cheap piece of Chinese electronics found in the clearance bin at Walmart. There’s a small radio operating at 433MHz, a temperature sensor, and a microcontroller under a blob of epoxy. The microcontroller and transmitter board in the temperature sensor were only attached by a ribbon cable, and each of the lines were labeled. After finding power and ground, [bhunting] took a scope to the wires that provided the data to the radio and took a look at it with a logic analyzer.

After a bit of work, [bhunting] was able to figure out how the temperature sensor sent data back to the base station, and with a bit of surgery to one of these base stations, he had a way to read the temperature data with an Arduino. From there, it’s just a data logging problem that’s easily solved with Excel, and [bhunting] has exactly what he originally wanted, thanks to a find in the Walmart clearance bin.

Know Your Speed on Rollerblades

[Anurag] is a computer engineering student with a knack for rollerblading. Rollerblades are not a transportation device that are often fitted with speedometers, so [Anurag] took that more as a challenge and designed this Arduino-powered computer to give him more information on his rollerblade rides.

The device uses an Arduino as the brain, and counts wheel revolutions (along with doing a little bit of math) in order to calculate the speed of the rider. The only problem with using this method is that the wheels aren’t on the ground at all times, and slow down slightly when the rider’s foot is off the ground. To make sure he gets accurate data, the Arduino uses an ultrasonic rangefinder to determine the distance to the ground and deduce when it should be taking speed measurements.

In addition to speed, the device can also calculate humidity and temperature, and could be configured to measure any number of things. It outputs its results to a small screen, but it could easily be upgraded with Bluetooth for easy data logging. If speed is truly your goal, you might want to have a look at these motorized rollerblades too.

Captain Hermano’s Mystery Box is Full of Puzzles

[Raffi] needed a birthday present idea but he wanted to do something extra special. He realized that a big part of gift giving is the anticipation and excitement of opening the present. In order to prolong this experience, [Raffi] built an electronic puzzle box. The box contains the final gift, but first a series of puzzles must be solved in order to open the box.

The project runs on an Arduino Mega. This is hooked up to several sensors, including a temperature sensor, GPS unit, and CO sensor. There is also an LCD screen and numeric keypad for user input and output. The project page contains a flow chart that shows all of the puzzles and their solutions. One of the more interesting puzzles requires the user to blow tobacco smoke into a tube. The CO sensor detects the smoke and unlocks the next puzzle.

Some of the puzzles require interacting with outside systems. For example, one puzzle requires the user to send an email to the fictional Captain Hermano’s email address. If the correct keyword is included in the email, the user will receive a reply with the code to enter into the box. Another puzzle requires the user to call a particular phone number and listen for another riddle. We’ve included the video demonstration below.

This isn’t the first puzzle box we’ve seen, but each one has its own special flair. This one is very well made and looks like a lot of care was put into it. We’ve seen another that uses only discrete components. We’ve seen yet another that uses Morse code. Continue reading “Captain Hermano’s Mystery Box is Full of Puzzles”

Chinese Temperature/Humidity Sensor is Easily Hacked

There’s a new piece of electronics from China on the market now: the USR-HTW Wireless Temperature and Humidity Sensor. The device connects over Wi-Fi and serves up a webpage where the user can view various climate statistics. [Tristan] obtained one of these devices and cracked open the data stream, revealing that this sensor is easily manipulated to do his bidding.

Once the device is connected, it sends an 11-byte data stream a few times a minute on port 8899 which can be easily intercepted. [Tristan] likes the device due to the relative ease at which he could decode information, and his project log is very detailed about how he went about doing this. He notes that the antenna could easily be replaced as well, just in case the device needs increased range.

There are many great reasons a device like this would be useful, such as using it as a remote sensor (or in an array of sensors) for a homemade thermostat, or a greenhouse, or in any number of other applications. The sky’s the limit!

Custom Raspberry Pi Thermostat Controller

Thermostats can be a pain. They often only look at one sensor in a multi-room home and then set the temperature based on that. The result is one room that’s comfortable and other rooms that are not. Plus, you generally have to get up off the couch to change the temperature. In this day and age, who wants to do that? You could buy an off-the-shelf solution, but sometimes hacking up your own custom hardware is just so much more fun.

[redditseph] did exactly that by modifying his home thermostat to be controlled by a Raspberry Pi. The temperature is controlled by a simple web interface that runs on the Pi. This way, [redditseph] can change the temperature from any room in his home using a computer or smart phone. He also built multi-sensor functionality into his design. This means that the Pi can take readings from multiple rooms in the home and use this data to make more intelligent decisions about how to change the temperature.

The Pi needed a way to actually talk to the thermostat. [redditseph] made this work with a relay module. The Pi flips one side of the relays, which then in turn switches the buttons that came built into the thermostat. The Pi is basically just emulating a human pressing buttons. His thermostat had terminal blocks inside, so [redditseph] didn’t have to risk damaging it by soldering anything to it. The end result is a functional design that has a sort of cyberpunk look to it.

[via Reddit]

Medical Tricorder Mark I

A handheld tricorder is as good a reason as any to start a project. The science-fiction-derived form factor provides an opportunity to work on a lot of different areas of hardware development like portable power, charging, communications between sensor and microcontroller. And of course you need a user interface so that the values being returned will have some meaning for the user.

[Marcus B] has done a great job with all of this in his first version of a medical tricorder. The current design hosts two sensors, one measures skin temperature using infrared, the other is a pulse sensor.

For us it’s not the number of sensors that makes something a “tricorder” but the ability of the device to use those sensors to make a diagnosis (or to give the user enough hints to come to their own conclusion). [Marcus] shares similar views and with that in mind has designed in a real-time clock and an SD card slot. These can be used to log sensor data over time which may then be able to suggest ailments based on a known set of common diagnosis parameters.

Looking at the image above you may be wondering which chip is the microcontroller. This build is actually a shield for an Arduino hiding underneath.

There’s a demonstration video after the break. And if you find this impressive you won’t want to miss the Open Source Science Tricorder which is one of the finalists for the 2014 Hackaday Prize.

Continue reading “Medical Tricorder Mark I”

End Table Kegerator Hides the Tap when You’re Not Looking

What’s better than an ordinary end table? How about an end table that can serve you beer? [Sam] had this exact idea and used his skills to make it a reality. The first step of the build was to acquire an end table that was big enough to hold all of the components for a functional kegerator. This proved to be a bit tricky, but [Sam] got lucky and scored a proper end table from a garage sale for only $5.00.

Next, [Sam] used bathroom sealant to seal up all of the cracks in the end table. This step is important to keep the inside cold. Good insulation will keep the beer colder, while using less electricity. Next, a hole was cut into the top of the table for the draft tower.

The draft tower is mounted to a couple of drawer slides. This allows the tower to raise up and down, keeping it out of sight when you don’t want it. The tower raises and lowers using a simple pulley system. A thin, high strength rope is attached to the tower. The other end is attached to a spool and a small motor. The motor can wind or unwind the spool in order to raise and lower the tower.

The table houses an Arduino, which controls the motor via a homemade H bridge. The Arduino is hooked up to a temperature sensor and a small LCD screen. This way, the users can see how cold their beer will be before they drink it.

To actually keep the beer cold, [Sam] ripped apart a mini fridge. He moved the compressor and condenser coils to the new table. He had to bend the coils to fit, taking care not to kink them. Finally he threw in the small keg, co2 tank and regulator. The final product is a livingroom gem that provides beer on demand.

Demo video (which is going the wrong way) can be found after the break.

Continue reading “End Table Kegerator Hides the Tap when You’re Not Looking”