Si.
Posts: 24
Joined: Mon Apr 30, 2012 2:53 pm
Contact: Website

Raspberry Pi and Wireless Sensor

Tue Jun 12, 2012 3:22 pm

A few weeks ago, I blogged about at a 'shield' that plugs into the Raspberry Pi's GPIO port called the 'Slice of Pi'. This very low cost board also includes an X-Bee shaped socket into which RF modules can be plugged. The company behind the 'Slice of Pi' (Ciseco) is also behind a useful and low-cost range of RF devices.

In this blog entry, I used one of their wireless sensor modules (in this case temperature) with a pair of XRF RF modems to add remote wireless temperature sensing to the Raspberry Pi.

http://www.doctormonk.com/2012/06/raspb ... ensor.html

Image

Threlkeld
Posts: 26
Joined: Thu Jun 07, 2012 4:25 pm

Re: Raspberry Pi and Wireless Sensor

Mon Jun 18, 2012 4:01 pm

Following the link gives a very positive impression. However, I do have a question.

The linked webpage describes commercial kit modules.
In giving the impression that the temperature sensor 'just plugs in' to the radio module, the need for first reprogramming the remote RF module firmware seems to have been ignored. The Ciseco website says:
"Note that in order to use a XRF radio module with a sensor, its personality needs to be changed by applying new firmware. This is free to download from here, but you will need a serial connection such as our FTDI Interface or similar to reprogram it."
The FTDI interface costs £20, and it is apparent from the website that the firmware upgrade process isn't always straightforward. Indeed, it sometimes bricks the module, which then needs to be returned for reprogrammimg.
Any comments on these apparent issues?

Threlkeld
Posts: 26
Joined: Thu Jun 07, 2012 4:25 pm

Re: Raspberry Pi and Wireless Sensor

Sat Aug 11, 2012 8:45 am

I've now got these very impressive wireless modules working. It is, as I implied above, a bit more complicated than it sounds.

On the good side, it is now possible to alter the remote XRF unit firmware to suit the application using the Raspberry pi as host. There is a good description of the procedure here:
http://openmicros.org/index.php/article ... spberry-pi
No need for the FTDI interface unit mentioned above.

The XRF transmitter units have a good range, and I've found that they work from inside freezers and fridges. Basically, the XRF plugged into the RasPi (using the inexpensive 'Slice of pi' adapter) listens out for signals from the remote XRF units. It can also send configuration commands to a remote unit. The raw readings coming back can be displayed on the Pi using a simple serial terminal such as Miniterm to verify correct operation. What happens after that is limited mainly by the Python programming skills of the user.

A number of remote XRF units can be monitored simultaneously. Each is given a two-character ID which is transmitted with each data packet. The units can monitor a number of environmental variables using small self-powered add-on boards with a few components that need to be assembled.

There is a support forum, and in my experience support there is almost instantaneous
http://openmicros.org/index.php/compone ... t?Itemid=0

pbalfe
Posts: 1
Joined: Fri Aug 24, 2012 8:42 am

Re: Raspberry Pi and Wireless Sensor

Fri Aug 24, 2012 8:48 am

Using the guidance in this post, we've used the Pi to build a -80°C freezer monitor. With email alarms, weekly reports and a website showing the current data as a simply python graph drawn by the Pi.

Check it out here:
http://www.infection.bham.ac.uk/VRG/Freezer.html

A PDF file describing how we did it is there as a link.

Hope it's useful!

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