NERP Tonight: A Simple Wireless Link for Serial Data

NERP is not exclusively Raspberry Pi, the small computer and embedded systems interest group at Pumping Station:One in Chicago. NERP meets every other Monday at 7pm at Pumping Station:One, 3519 N. Elston Ave. in Chicago.

Amongst the Maker community ZigBee® is usually thought of alongside the XBee® modules from Digi Corporation. The little blue irregular-hexagon shaped boards mean “wireless data” to a lot of folks. XBee is in fact the name of a family of wireless data modules that share the same form factor and blue color. The family includes ZigBee modules, DigiMesh modules, WiFi modules, and IEEE802.15.4 radios. Depending on the model, the data radios can do point-to-point, peer-to-peer, star, and mesh networks.

If you’d like to play around with wireless data a good place to start is replacing a serial cable with an XBee Series 1 module. There are two power levels to choose from: a 1mW module that can work to a distance of 300ft, and a 60 mW module that can work to a distance of one mile (in perfect conditions).

The Series 1 modules are usually used as IEEE 802.15.4 data radios. ZigBee and several other protocols are built on top of 802.15.4.The 802.15.4 spec provides the physical and MAC layers to serve higer level protocols. It’s a just enough support to get bytes sent from A to B. One nice thing about working close to the metal is that, once the hardware is set up, it’s fairly easy to push bytes around. You can even make up your own simple ad-hoc protocols if needed.

Tonight at NERP, I’ll show how to set up a wireless data link between two devices that can communicate at 300 to 115200 baud. I’ll show XBee XPB24-AWI-001’s moving serial data, and how to set up and test the modules using the X-CTU software from Digi.

As a side-note, the Internet of Things is creating a demand for better and cheaper wireless data connections. It is common for the Things to speak a local protocol that is propietary or unique to their class of device and for the relevant parts of the machine to machine dialog to be passed upstream through a server or bridge.

ZigBee® is a trademark of the ZigBee Consortium

Find NERP and Pumping Station:One at Doors open at 6:30pm. The next meeting is September 29th, 2014.
NERP is free and open to the public.
Ed Bennett ed @ kinetics and electronics com
Tags: electronics, embedded, NERP, Open Source,
raspberry pi, hackerspace, Beagle Bone, Element14, Pumping Station:One

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