07/29/2016 at 13:04 •
Since we are now using the tweepy library and the Met Office API, I can update the profile pic with different symbols according to the forecast. I got the icons from the excellent fa2png.io/. As with any update, check out the twitter feed linked on this page to see the results.
07/29/2016 at 12:17 •
Here is a rough overall system diagram for the project.
Various atmospheric sensors are interfaced to an mbed (probably one of the ST Nucleo boards because they're cheap, have much I/O and I like them) which acts as a sensor interface for the Pi Zero, probably communicating as an I2C slave. The sensor interface is included to separate the sensors from the main "brains", as we weren't 100% sure what platform that was going to be, and it also makes it easier to split the workload.
By far the most important sensors for our rocketry event application are the wind speed and direction sensors, with the temperature, humidity and pressure sensors included to round out the data.
The Pi Zero manages everything, taking and storing regular readings from the sensor interface, along with site photos from the Pi Cam. This data is sorted out and then, initially, sent to Twitter. Ideally in the long term it will also push to a website showing historical data, graphs and other fun things. Network connectivity is either via Ethernet, USB WiFi or a USB 3g/4g dongle. We aim to use Ethernet at EMF Festival and 3g/4g at International Rocketry Week, given the site's remote location.
Power is provided by a (massively oversized) solar panel, rescued from a dead project. Long term plan is for an MPPT charge controller (maybe homemade?) charging a reasonably sized 12V SLA battery, but this may not be in place for EMF. Panel and battery voltages will be read by the sensor interface, and any telemetry output by the eventual MPPT controller will also go into the sensor interface.
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