Mavrk wireless weather station communication system


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Mavrk wireless weather station communication system

  1. 1. By: Bill Gesner
  2. 2. Goal Receive weather information from two RJ-11 connectors(phone jacks). Transmit the data wirelessly from the Texas Instrument micro Mavrk to a Texas Instrument Mavrk. Send the data to a PC and a secondary embedded device.
  3. 3. Weather Meter Design Rain Gauge: The rain meter pools water which causes a circuit to close once per 0.011” of rain. Anemometer: The speed of the wind is recorded by closing a circuit once per rotation. Wind Direction: The direction of the wind causes a change in resistance across the output.
  4. 4. Input circuit design
  5. 5. Rain Gauge Input A digital input port was used to detect the current state of the circuit. The number of times the circuit was closed was counted. Once every two seconds the count was transmitted wirelessly to the base station. The data was sent to the PC via USB as well as the serial port.
  6. 6. Wind Speed Input Similar to the Rain gauge method. The Anemometer circuit closes once per revolution. A wind speed of 2.4 km/h causes the switch to close once per second. The amount of times the Anemometer circuit closed was counted and transmitted once every five seconds.
  7. 7. Wind Vane Input The direction of the wind alters the resistance across the wind vane output. An analog to digital converter input was used to detect the voltage drop across the wind vane which was connected in series to a 10kOhm resistor. The value of the ADC was transmitted wirelessly once every two seconds.
  8. 8. Temperature A built in temperature sensor is included on the micro Mavrk. The temperature sensor output is connected to the ADC similar to the wind vane input Functionality of the temperature sensor is optional to allow for the possibility of an extra ADC input.
  9. 9. Humidity A secondary chip can be attached to the micro Mavrk to add humidity detection. The TMP-112 replaces the output of the built in temperature sensor with the output of a humidity sensor. The temperature data is then available via I2C with more precision.
  10. 10. Light The brightness in the room can be read from the micro Mavrk. This functionality can be enabled using the standard micro Mavrk or the TMP-112.
  11. 11. Output The output of the data is then sent to the Texas Instrument demonstration software “App Monitor”. This displays all built in functionality such as temperature, humidity, and light levels. The raw data is also transmitted serially via UART.
  12. 12. UART output packet structure The data sent to secondary embedded hardware required a data structure to ensure valid transmission. In total 7 bytes were transmitted 2 byte header 1 byte to identify what sensor was transmitting data 2 bytes of data 2 byte footer
  13. 13. Conclusions The mavrk system is a modular and versatile development platform that can be used for swift prototyping. The sparkfun weather station is straight forward and well documented Code Composer is an easy to use and friendly environment.