The Arduino weather station is coming along. Today I integrated a barometric pressure sensor and a calibrated light sensor into the hardware and software. The pressure sensor is a SPC1000-D01, which is sensitive to pressure changes as small as the difference within a 9 cm column of air. It can be used in several different configurations depending on how often you want to get a reading, and how much precision it reports. At the best frequency and precision, the sensor was drawing enough current that I was having trouble adding other sensors to the Arduino, so I’m running it in it’s lowest power configuration (where the chip is in a low power standby mode until you ask it for a reading). The light sensor is a TSL230R, which is also very accurate. It has three different sensitivity levels that can be changed at any time, which means that when the light intensity gets too high or low, the Arduino changes the sensitivity of the sensor to keep the results within range. The only down side to these chips are they require a lot of digital pins (four for the pressure sensor, five for the light sensor).
Here’s a circuit diagram of the current setup. If you click the image, you can view a PDF version. There’s also an Arduino xcircuit diagram. This is the first circuit I’ve ever tried to draw, so it probably isn’t as well laid-out at it should be.
The code is also available. It’s not pretty, but it works. If you do download it, the code include a simple analog light sensor (light0), which isn’t shown on the wiring diagram. I was using it before I got the new sensor set up, and haven’t removed it from the hardware yet.