In this chapter, we will make an outdoor weather station that is accessible over the Internet, which will allow remote monitoring and recording of the weather conditions.
To do this, we will have a look at a new skill that will allow us to take some existing sensors and adapt them for use in our project—reverse engineering. This is essentially the process of taking a part of an existing product and deriving the communication method between it and the rest of the product, so that you can replace either a specific part or a whole product.
We will also take a quick look at how to use the Pi as a web server and the method used to develop and deploy a Python web application.
This is a list of all the parts you will need in order to complete this project. Most of these are available at high-street electronic components stores and online distributors:
- A Raspberry Pi
- A Wi-Fi dongle
- A long micro USB cable
- A clear/translucent Tupperware box
- A DHT11 (www.adafruit.com/product/386) or DHT22 (www.adafruit.com/products/385) sensor
- BMP180 (www.adafruit.com/product/1603)
- A Maplin anemometer (wind speed sensor) (www.maplin.co.uk/p/maplin-replacement-wind-speed-sensor-for-n96fy-n82nf)
- A Maplin wind direction sensor (www.maplin.co.uk/p/maplin-replacement-wind-direction-sensor-for-n96fyn96gy-n81nf)
- A Maplin rain gauge (www.maplin.co.uk/p/maplin-replacement-rain-gauge-for-n25frn96fyn96gy-n77nf)
- An Arduino Uno (www.adafruit.com/product/50)
- A selection of resistors (www.maplin.co.uk/p/e12-025w-resistor-610-piece-pack-fa08j)
- A 1 inch square section of a stripboard (www.maplin.co.uk/p/veroboard-copper-stripboard-100x160mm-a62rl)
- A row of four 0.1 inch pin headers
- A strip of terminal blocks
- Male-to-male pin jumper wires
- Female-to-female pin jumper wires
Note that even though I have specifically listed an Arduino Uno, any standard 8-bit AVR-based Arduino should work fine for this project, for example, the Uno, Mega, Nano, and Duemilanove.
I have also specified two different DHT sensors that can be used. The only real difference between them is that DHT22 has a wider operating range than DHT11; DHT11 can read temperatures between 0 and 50 degrees Celsius and humidity between 20 and 80 percent RH (relative humidity), whereas the DHT22 can read temperatures between -40 to 80 degrees Celsius and humidity between 0 to 100 percent RH.
We will make use of different valued resistors a couple of times. These are small devices that are used to limit the flow of current through a circuit. Their resistance is measured in Ohms and is denoted by Ω. Since these devices do not have their resistance value printed on them, a color code must be used. To find the color code used to denote a particular resistance, a good reference chart can be found at www.digikey.co.uk/en/resources/conversion-calculators/conversion-calculator-resistor-color-code-4-band. Throughout this chapter, resistors are referred to by both value and color code.
Note that we will not use the full pack of resistors I provided a link to. However, they are very handy to have as having to order parts like resistors as and when they are needed slows down this type of electronics project.