[Don] wanted to bring his alarm system into the modern age. He figured that making it more connected would do the trick. Specifically, he wanted his alarm system to send him an SMS message whenever the alarm was tripped.
[Don] first had to figure out a way to trigger an event when the alarm sounds. He found a screw terminal that lead to the siren. When the alarm is tripped, this screw terminal outputs 12V to enable the siren. This would be a good place to monitor for an alarm trip.
[Don] is using an Arduino nano to monitor the alarm signal. This meant that the 12V signal needed to be stepped down. He ran it through a resistor and a Zener diode to lower the voltage to something the Arduino can handle. Once the Arduino detects a signal, it uses an ESP8266 WiFi module to send an email. The address [Don] used is the email-to-SMS address which results in a text message hitting his phone over the cell network.
The Arduino also needed power. [Don] found a screw terminal on the alarm system circuit board that provided a regulated 12V output. He ran this to another power regulator board to lower the voltage to a steady 5V. This provides just the amount of juice the Arduino needs to run, and it doesn’t rely on batteries. [Don] provides a good explanation of the system in the video below. Continue reading “Adding WiFi and SMS to an Alarm System”
Have you ever wanted to send a quick message to your HAM radio buddies over the air but then realized you forgot your radio at home? [Troy] created Oinker to remedy this problem. Oinker is a Perl script that turns emails into audio.
The script monitors an email account for new messages and then uses the Festival text-to-speech engine to transform the text into audio. [Troy] runs Oinker on a Raspberry Pi, with the Pi’s audio output plugged directly into an inexpensive ham radio. The radio is then manually tuned to the desired transmit frequency. Whenever Oinker see’s a new email, that message is converted into speech and then output to the transmitter.
The script automatically appends your HAM radio call sign to the end of every message to ensure you stay within FCC regulations. Now whenever [Troy] runs into some bad traffic on the road, he can send a quick SMS to his email address and warn his HAM radio buddies to stay clear of the area.
When the power went out at his parents’ shop and ruined the contents of their fridge, [Lauters Mehdi] got to work building a custom power failure alert system to prevent future disasters. Although some commercial products address this problem, [Lauters] decided that he could build his own for the same cost while integrating a specific alert feature: one that fires off an SMS to predefined contacts upon mains power failure.
The first step was to enable communication between an Arduino Micro and a Nokia cell phone. His Nokia 3310 uses FBus protocol, but [Lauters] couldn’t find an Arduino library to make the job easier. Instead, he prototyped basic communication by running an Arduino Uno as a simple serial repeater to issue commands from the computer directly to the phone, and eventually worked out how to send an SMS from the ‘duino. [Lauters] then took the phone apart and tapped into the power button to control on/off states. He also disconnected the phone’s battery and plugged it into an attached PCB. The system operates off mains power but swaps to a 1000mAH 9V backup battery during a power outage, logging the time and sending out the SMS alerts. A second message informs the contacts when power has been restored.
Head over to [Lauters’s] project blog for schematics and photos, then see his GitHub for the source code. If you want to see other SMS hacking projects, check out the similar build that keeps a remote-location cabin warm, or the portable power strip activated by SMS.
For how awesome Google Voice is, we’re surprised we haven’t seen this before. [Steve] is using Google Voice to run commands on just about any Linux box.
Google Voice doesn’t have an official API, and existing unofficial APIs weren’t up to snuff for [Steve]’s project. He ended up writing his own that checks his unread message inbox every minute and looks for new text messages beginning with the phrase, ‘Cmd’. If a series of checks pass – the text coming from a known phone number and a proper terminal command – the command runs and sends the a text back indicating success or failure.
While [Steve] probably won’t be playing nethack or Zork via SMS anytime soon, we can see this being very useful for a Raspi home automation task. Just send a text message and a properly configured Linux box can open your garage door, turn on the lights, or even start a webcam.