May 3rd, 2009

Monitoring Weather

Weather Station

I remember back in 1996 after i saw for the first time “Twister”, i was so hooked on ways to measure weather parameters by myself. APT reception of weather satellites, VLF radio, temperature monitoring… you name it, my backyard was filled with antennas, each one bigger than the other. Now when i found this awesome weather station project all those memories returned and my soldering station is heating up.

This weather station measures the most important weather parameters: temperature, pressure and relative humidity. You can select to view temperature in Celsius or Fahrenheit degrees and pressure in mbar/hPa or mmHg. The station can also measure the temperature from a remote location using RX,TX433 wireless modules.

The data is displayed on a LCD along with the date and time, the highest and lowest temperature in the past 42 hours and a graphical histogram. To increase its autonomy the weather station has a sleep mode, it wakes up only to gather the data from the sensors, memorize it and display it. Looking at the schematic you will see it uses MOSFET transistors as switches controlled by the PIC18F452 to power up sensors and RX/TX modules to preserve battery life.

Operation of the weather station is done using the three buttons. One button brings the menu and the other two are used to navigate in it, or too navigate through memorized data.  Pressing any of these buttons will awake the station from its sleep mode. Another thing to mention is that the data will not be lost if the station loses power.

The sensors used are MPX4115A for pressure measurement, TC77 SPI for temperature and H1 sensor takes care of humidity reading. The H1 outputs a capacitance so its used with a 555 oscillator, whose frequency depends on the humidity reading. PIC18F452 is the brain of the receiver station and PIC16F84 takes care of the transmitter.

All schematics, PCB layouts, hex files and source codes are available in the project.

Monitoring Weather: [Link]

Michael Sung writes:

The SAK2 (Swiss-Army-Knife 2) Board, is a very flexible data acquisition board that serves as the central sensor hub for the MIThril 2003 distributed system architecture. The SAK2 board was designed primarily to interface a variety of sensing technologies with mobile device-based wearable platforms to enable real-time context-aware, streaming data applications. The SAK2 is an extremely flexible data acquisition hub, allowing for a wide variety of custom as well as third-party sensors to interface to it. In addition to being a sensor hub, the SAK2 can also operate in stand-alone mode for a variety of long-term data acquisition and real-time interactive applications.

SAK2 Sensor Hub and Interface Board Hardware

The SAK2 was designed and intended for general use by research groups at the MIT Media Laboratory as well as other research communities at large. The following links provide all the design files necessary to replicate the MIT Wearables Group’s hardware setup. On the hardware side, we recommend the MPLAB 6.5 microcontroller development environment, the CCS compiler, and the PICStart Plus programmer. We support a variety of linux-based tools called Enchantment to stream data in real-time from the SAK2 hub through the 803.11b infrastructure (via the Zaurus or other linux-based device). We are currently working on a much cleaner, modular, and buffered version of the SAK2 firmware which should be available in May, 2004.

Michael Sung

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