Interesting Tech Projects
Posts tagged raspberry pi
PCB For Raspberry Pi WH1080 Weather Station
Nov 15th
Previously I wrote about using a Raspberry Pi to receive 433MHz signals from a WH1080 weather station. This is the mess of wiring I came up with:
This worked fine until it stopped. I probably didn’t crimp a wire properly and too many knocks resulted in unreliable operation. To solve this I designed a PCB that connects the radio receiver, pressure sensor and an antenna to a Raspberry Pi:
The design is very simple:
It accepts a surface-mount version of the RMF01 module (the version with a black resin blob). This is easily soldered onto the PCB by hand.
A female through-hole SMA connector is used for the antenna connection. This allows a range of off-the-shelf antennas to be used. The one I purchased from eBay didn’t work so I modified it as can be seen in the pictures. Alternatively a wire can be directly soldered to the board.
Finally a six pin BMP085 module is connected to a header. The pinout of the BMP085 module used is:
- Pin 1 = 3.3V
- Pin 2 = SDA
- Pin 3 = SCL
- Pin 4 = No connection
- Pin 5 = No connection
- Pin 6 = Ground
Here is how the PCB looks when populated:
Download the schematic diagram (15MB).
I have some spare boards, so if you would like one to experiment with please contact me.
Update: All the spare boards are gone. I hope everyone who received one has a lot of fun with them!
Here are the gerber files, suitable for submitting to a PCB house. The license is CC-BY-NC SA. I.e. for personal non-commercial use only. Sorry, but I am unable to provide support for these files.
WH1080 Weather Station and Weather Underground
Jun 7th
A couple of years ago I bought a WH1080 weather station (e.g. Fine Offset, Mapin). It’s available under many brands from many outlets all over the world and is very common. Here are pictures of what this cheap weather station looks like:
I had the touchscreen connected to a Linux sever via USB and used pywws to upload to Weather Underground. This worked well until USB broke so I had to look for a new solution.
Kevin Sangeelee had developed some code that allowed a Raspberry Pi to receive the 433MHz radio signals and decode them. It also had support for a pressure sensor. Perfect. The code can be found here: http://www.susa.net/wordpress/2012/08/raspberry-pi-reading-wh1081-weather-sensors-using-an-rfm01-and-rfm12b/
The RFM01 was obtained from Maplin for about £4 and was trivially connected to the RPi. Kevin’s article gives the connections. Note: I didn’t use any resistors.
The BMP085 was also easily connected. Purchased from eBay for about £6 it connects directly to the I2C pins. Again, no resistors needed.
The first step was up update Kevin’s code for revision 2 of the RPi. This is required because a GPIO pin has changed and the second I2C bus is now used.
Now I ran into a stumbling block – how to get the data into pywws. I hoped that this problem had already been solved but unfortunately I would have to start writing custom python modules. After thinking about it for a while I decided that all I needed was to upload data to Weather Underground. I didn’t need the other features of pywws. Fortunately Weather Underground has a simple way of uploading using a HTTP GET request. The data just needed to be massaged into the correct format. While I was at it I decided to use the rapid-fire updating. This means that Weather Underground displays new data from your station roughly every 48 seconds – you can watch it continually update.
You can get the code from GitHub here: https://github.com/ajayre/WH1080-Weather-Underground.
Create a text file in the same folder as the executable called wunderground_creds.txt. On the first line enter the name of your weather station ID, for example IWESTYORKS30. On the second line enter your Weather Underground password.
Compile, run and follow Kevin’s instructions for setting up and tuning. Don’t forget to enable the SPI and I2C modules on the RPi. Also make sure you run:
sudo dpkg-reconfigure tzdata
to set the timezone.
Make sure the path to the credentials file in wunderground.c is set correctly. To start the program on boot I used the following in a boot script:
sudo screen -d -m /home/pi/weather/wh1080_rf
