[BaronVonSchnowzer] is spinning up some home automation and settled on an inexpensive ambient temperature sensor which is sold to augment the data a home weather station collects. He found that the RF protocol had been reverse engineered and will use this information to harvest data from a sensor in each room. In true hacker fashion, he rolled his own advances out to the Internet so that others may benefit. Specifically, he reverse engineered the checksum used by the Ambient F007TH.
He got onto this track after trying out the Arduino sketch written to receive the sensor’s RF communications. One peculiar part of the code turned out to be a filter for corrupt messages as the protocol’s checksum hadn’t yet been worked out. Figuring out how the checksum byte owrks wasn’t an easy process. The adventure led him to dump 13k samples into a spreadsheet to see if sorting similar sets of 5-byte message and 1-byte checksum would shed some light on the situation. The rest of the story is some impressive pattern matching that led to the final algorithm. Now [BaronVonSchnowzer] and anyone else using these modules can filter out corrupt data in the most efficient way possible.
Yes, it’s a weather station, one of those things that records data from a suite of sensors for a compact and robust way of logging atmospheric conditions. We’ve seen a few of these built around Raspberry Pis and Arduinos, but not one built with a Phidget SBC, and rarely one that has this much thought put in to a weather logging station.
This weather station is designed to be autonomous, logging data for a week or so until the USB thumb drive containing all the data is taken back to the lab and replaced with a new one. It’s designed to operate in the middle of nowhere, and that means no power. Solar it is, but how big of a solar panel do you need?
That question must be answered by carefully calculating the power budget of the entire station and the battery, the size of the battery, and the worst case scenario for clouds and low light conditions. An amorphous solar cell was chosen for its ability to generate power from low and indirect light sources. This is connected to a 12 Volt, 110 amp hour battery. Heavy and expensive, but overkill is better than being unable to do the job.
Sensors, including temperature, humidity, and an IR temperature sensor were wired up to a Phidgets SBC3 and the coding began. The data are recorded onto a USB thumb drive plugged into the Phidgets board, and the station was visited once a week to retrieve data. This is a far, far simpler solution than figuring out a wireless networking solution, and much better on the power budget.
Via embedded lab
When [Ioannis] received some high resolution LCD’s in a tattered foam box, he posed to himself a most interesting question – Should he throw the foam box away, or use it as a container for a project? Fortunately for us, he decided on the latter and threw together a very capable weather station!
Having only an hour to spare, [Ioannis] grabbed a Raspberry Pi, WiFi USB stick and a camera module and went to work. He mounted the camera module to the foam lid using a highly advanced technique, and soldered a cable that would power the device directly to D17 – a Zener diode that sits on the bottom of the board.
For the weather data, he’s using another design of his – the Sensor Stick. This nifty device — which we featured over the weekend — is about the size of a stick of chewing gum, and sports an array of sensors including the popular BMP085, which can measure pressure and temperature .
He wraps up everything using open source software to get the data from the weather station. Pretty impressive for an old foam box and an hours time! This would be an interesting start to a home automation system. Connect it to motorized windows and/or a sprinkler system and he’s on his way to claiming The Hackaday Prize.
[Spock] wanted to do a little reverse engineering of his Miele brand remote control vacuum cleaner, so he broke out his DVB-T SDR dongle to use as a spectrum analyser. Sure enough, he found a 433.83Mhz signal that his vacuum cleaner remote control was using, but to his surprise, he found a stray
QAM256 signal when he expected an ASK only one.
After a little detective work, [Spock] eventually tracked it down to a cheap weather station he had forgotten about. The protocol for the weather station was too compelling for him to go back to his vacuum cleaner, though. After
downloading an rc-switch Arduino library and making a quick stop at his local radio shack to get a 433.92 radio receiver to decode the signal, he reverse engineered the weather station so he could digitally record the temperature output. The Arduino rc-switch library proved unable to decode the signal, but some Python work helped him get to the bottom of it.
With software defined radio becoming more accessible and common place, hacks like these are a nice reminder just how wired our houses are becoming.
[Afonso] picked up a cheap energy use monitor a few years back. He really like the data it displays about his home’s electricity, using a sensor to gather this info and a display that communicates with it wirelessly. But there is no option to log or dump the data. He set out to reverse engineer the wireless protocol in order to extend the use of the system. As the name of this column implies, he failed to get this working.
The hardware above is a 433Mhz transceiver that he rigged up as test hardware. It sounds like he’s assuming the monitor works on this band, which could have been his first misstep (we really don’t know). The speaker is there to give audible confirmation that he’s receiving something from the transmitter. This is where things start to get pretty weird. White noise was coming from the speaker, but when he stepped away from the bench it stopped. He was able to measure a regular pattern to the noise, and proceeded to place the speaker next to his computer MIC so that he could record a sample for further analysis.
Fail of the Week always aims to be a positive experience. In this case we’d like to have a conversation about the process itself. We agree that connecting a speaker (or headphones) should help get your foot in the door because your ear will recognize a rhythmic pattern when it is received. But with this noise, measuring the timing and recording a sample we’re not so sure about. Given the situation, how would you have soldiered on for the best chance at successfully sniffing out the communication scheme used by this hardware? Leave a comment below!
Fail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.
With his meteorological interests, [Carl] builds weather stations. Temperature and humidity sensors are a dime a dozen, but with his DIY ingenuity, [Carl] has built some very interesting and complicated devices. The latest of which is an ultrasonic wind sensor that uses the time of flight of ultrasonic pulses to detect how fast the wind is blowing.
[Carl]’s sensor uses four ultrasonic transducers aligned to North, South, East, and West to detect the wind speed. By measuring the time it takes an ultrasonic pulse to travel between the sensors indoors, Subtracting the in-situ measurement gives him the time of flight for each axis, and thus the wind speed.
It’s an impressive display of engineering that comes with an amazingly detailed design report. After three months of operation, [Carl] has found his ultrasonic anemometer is better than the traditional mechanical ‘egg-cup’ anemometer at measuring low wind speeds. The only real problem with the build is the fact the design makes a great bird perch, but some fine steel wire quickly corrected that problem.
Everyone loves getting something you can play with as a Christmas gift. [Thomas] was the lucky recipient of an Elektor USB weather station kit. But the fun didn’t end once he had assembled everything. He went on to hack the device for wireless data collection.
Shown above is the weather station board connected to the transmitter. The red board with a tiny antenna to the right is a Rovio RN-VX module. It is capable of transmitting serial data to its twin on the receiving end of the setup. The weather station is pretty easy to connect to the transmitter since it feeds serial data to an FTDI USB chip. [Thomas] simply connected power and ground, then added a jumper from the board’s TX pin to the Rovio’s RX pin. The receiving end uses a serial-to-USB converter — getting a signal for its RX pin from the TX pin on the Rovio receiver board.
We know from other projects that these radio modules can connect to a WiFi AP. Perhaps a future revision of [Thomas’] hack will allow the weather station to communicate with his server over the network, doing away with the need for a standalone receiver.