Build Instructions

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• 1

  Step 1

  The WeatherPi Block Diagram looks a lot more complicated than it actually is.

  The first thing to notice that the dashed lines are individual boards (WeatherPiArduino and SunAirPlus) which contain a lot of the block diagram and the second thing is that all of the sensors to the left of the diagram plug into the WeatherPiArduino board which simplifies the wiring. Don't be intimidated!

  The Subsystems

  The Power Subsystem of WeatherPi uses a SunAirPlus Solar Power Controller which handles the solar panels, charging of the battery and then supplies the 5V to the Raspberry Pi and the rest of the system. It also contains sensors that will tell you the current and voltage produced by the Solar Panels and consumed by the batteries and the Raspberry Pi. Gather that Data! More Cowbell! It also contains the hardware watchdog timer and the USB PowerControl that actually shuts off the power to the Raspberry Pi during a brownout event (after the Pi shuts gracefully down under software control).

  The Sensor Subsystem of WeatherPi uses a WeatherPiArduino as the base unit and then plugs in a bunch of optional sensors such as wind speed / direction / rain, lightning detection (how cool is that!), inside and outside temperature and humidity.

  The Software Subsystem of WeatherPi runs in Python on the Raspberry Pi. It collects the data, stores in in a MySQL database, builds graphs and does housekeeping and power monitoring.

• 2

  Step 2

  The WeatherPi Sensor Suite senses the following environmental values:

  • Wind Speed
  • Wind Direction
  • Rain
  • Outside Temperature
  • Outside Humidity
  • Lightning Detection
  • Barometric Pressure (and Altitude)
  • Inside Box Temperature
  • Inside Box Humidity

  You can add more to the I2C bus and Analog to Digital Converter such as UV, dust counts, light color (sensing some types of pollution) and more! It's a great platform for expansion.

  The sensor suite is built on the WeatherPiArduino board but there are several similar boards out there on the market.

• 3

  Step 3

  What's On the I2C Bus?

  WeatherPi makes extensive use of the I2C bus on the Raspberry Pi.

  At SwitchDoc Labs, we love data. And we love I2C devices. We like to gather the data using lots of I2C devices on our computers and projects. Project Curacao has a total of 12, WeatherPi has 11 devices and SunRover (a solar powered rover under development at SwitchDoc - you will see it as an Project in fall 2015) will have over 20 and will require one I2C bus just for controlling the motors. We are always running into conflicts with addressing on the I2C device. Since there are no standards, sometimes multiple devices will have the same address, such as 0x70 and you are just out of luck in running both of them on the same I2C bus without a lot of jimmy rigging.

  To get around this addressing problem (and our conflict with an INA3221 and the Inside Humidity Sensor) we added an I2C Bus Multiplexer to the design which allows us to have many more I2C devices on the bus, irregardless of addressing conflicts. Here is our current list of I2C devices in WeatherPi:

  Device:I2C Address

  BMP180 Barometric Pressure: 0x77

  Real Time Clock DS3231: 0x68

  ATC EEPROM: 0x56

  ADS1015 Analog to Digital Converter: 0x49

  FRAM non-volatile storage: 0x50

  ADS1015 on SunAirPlus: 0x48

  INA3221 3 Channel Voltage/Current Monitor on SunAirPlus: 0x40

  HTU21D-F Humidity Sensor: 0x40

  Embedded Adventures Lightning Detector: 0x03

  AM2315 Outdoor Temp/Humidity: 0x5C

  I2C 4 Channel I2C Bus Mux: 0x73

  Here is what the I2C bus looks like on the Raspberry Pi. This is the output from the example code with the I2C 4 Channel Mux (hence there are 4 independent busses shown for the I2C bus).

  Note that WeatherPi only uses Bus 0 and Bus 1.

  Test SDL_Pi_TCA9545 Version 1.0 - SwitchDoc Labs
  
  Sample uses 0x73
  Program Started at:2015-05-10 20:00:56
  
  -----------BUS 0-------------------
  tca9545 control register B3-B0 = 0x1
  ignore Interrupts if INT3' - INT0' not connected
  tca9545 control register Interrupts = 0xc
       0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
  00:          03 -- -- -- -- -- -- -- -- -- -- -- -- 
  10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  40: 40 -- -- -- -- -- -- -- -- 49 -- -- -- -- -- -- 
  50: 50 -- -- -- -- -- 56 -- -- -- -- -- -- -- -- -- 
  60: -- -- -- -- -- -- -- -- 68 -- -- -- -- -- -- -- 
  70: -- -- -- 73 -- -- -- 77                         
  
  -----------------------------------
  
  -----------BUS 1-------------------
  tca9545 control register B3-B0 = 0x2
  ignore Interrupts if INT3' - INT0' not connected
  tca9545 control register Interrupts = 0xe
       0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
  00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
  10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  40: 40 -- -- -- -- -- -- -- 48 -- -- -- -- -- -- -- 
  50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  70: -- -- -- 73 -- -- -- --                         
  
  -----------------------------------
  
  -----------BUS 2-------------------
  tca9545 control register B3-B0 = 0x4
  ignore Interrupts if INT3' - INT0' not connected
  tca9545 control register Interrupts = 0xc
       0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
  00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
  10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  70: -- -- -- 73 -- -- -- --                         
  
  -----------------------------------
  
  -----------BUS 3-------------------
  tca9545 control register B3-B0 = 0x8
  ignore Interrupts if INT3' - INT0' not connected
  tca9545 control register Interrupts = 0xc
       0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
  00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
  10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
  70: -- -- -- 73 -- -- -- --                         
  
  -----------------------------------

  
  

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