An Awesome Wireless Motion Sensor

sensorWireless sensor networks are nothing new to Hackaday, but [Felix]‘s wireless PIR sensor node is something else entirely. Rarely do we see something so well put together that’s also so well designed for mass production.

For his sensor, [Felix] is using a Moteino, a very tiny Arduino compatible board with solder pads for an RFM12B and RFM69 radio transceivers. These very inexpensive radios – about $4 each – are able to transmit about half a kilometer at 38.4 kbps, an impressive amount of bandwidth and an exceptional range for a very inexpensive system.

The important bit on this wireless sensor, the PIR sensor, connects with three pins – power, ground, and out. When the PIR sensor sees something it transmits a code the base station where the ‘motion’ alert message is displayed.

The entire device is powered by a 9V battery and stuffed inside a beautiful acrylic case. With everything, each sensor node should cost about $15; very cheap for something that if built by a proper security system company would cost much, much more.

RF wireless kernel module for Raspberry Pi, BeagleBone and others

rfm12b-kernel-module

If you’ve done any wireless work with hobby electronics you probably recognize this part. The green PCB is an RFM12B wireless board. They come in a few different operating bandwidths, the 433 MHz is probably the most common. They’re super easy to interface with a small microcontroller but what about an embedded Linux board? That is the focus of this project, which builds a kernel driver for the RF module.

You can get your own RFM12B for a few bucks. They’re quite versatile when paired, but a lot of inexpensive wireless consumer goods operate on this band so the board can be used to send commands to wireless outlets, light fixtures, etc. [Georg] has been working with the BeagleBone, BeagleBone Black, and Raspberry Pi. His software package lets you build a kernel module to add an entry for the device into the /dev directory of a Linux system. So far the three boards listed are all that’s supported, but if you have five I/O pins available it should be a snap to tailor this to other hardware.

Wondering what else you can do with the setup? This will get the receiving end of a text-messaging doorbell up and running in no time.

[Read more...]

Doorbell to Internet bridge also useful for other home automation

This wireless doorbell hack can send a text message when someone rings. Adding the hardware to the chime unit turned out to be quite simple. It shows potential for a slew of other applications.

[Martin] started the project with a breakout board he had designed for an RFM12B wireless transceiver board. This board is popular because of its low-cost, small size, and ease of operation. [Martin's] breakout is barely larger than the RFM module itself, and merely adds an ATtiny84 to the mix. In the case of this doorbell project he uses a pin interrupt to detect when the doorbell’s LED is illuminated. This wakes the chip from sleep and sends a message back to the receiver that something has happened.

The receiver can do anything it wants with that data. In this case it uses an email-to-SMS service to send [Martin] a text message. But the home automation applications are vast for this simple hardware. We have a water heater that is not near a floor drain so we use a simple leak detector to sound an alarm if there is ever a problem (the water heater sits in a shallow tray). That works if we’re home at the time. Using [Martin's] solution could extend that alarm’s reach worldwide.

[via Hacked Gadgets]