Weather Station Part II

    Well, I am finally getting back to this project after some time. This part will describe the new electronics to be placed inside the anemometer. Off we go...

    The heart of the system is a Propeller microcontroller. At the end of Part I, I said I was going to use a PIC microcontroller, but I have instead decided to use the Prop. The reason is that I am somewhat of a fan of the Prop for its ease of programming and power inside the 44 pin package. Given the simple nature of the sensors, it's not necessary to use assembly language and Spin will work nicely. For anyone who is unfamiliar with Spin, it is a form of basic specific to the Propeller microcontroller. Head here for more information on the Propeller.

Here is the schematic of the Transmitter section.
You can download a PDF version here.

    As you can see, aside from the Prop, there is a 32K EEPROM for program storage, a 3.3V regulator, and the DS18S20 digital temp sensor. P2 contains the control and power, P1 is for the rain gauge(which is nothing more than a reed switch), and P3 connects to the wires from the anemometer from Part I.
    P2 will be hard wired using 6 conductor phone wire to the receiver unit in the house for direct connection and two way access. By hard wiring the transmitter, it gets me away from using batteries (which was one of my original complaints), and allows for instant access to the sensors if I wish it. Eventually, I will be integrating everything into Windows Media Center, so being able to access data on the fly is required.

    Here you can see the top of the board. In the center is the Prop, the top left corner is the temp sensor, mid left is the EEPROM, top right is P2, bottom right is P1(Rain gauge), and bottom left is P3.


    Here is the bottom of the board, and roughly top center is the 3.3v regulator.

    Here the almost finished transmitter. The connection on the left is the main connection to the receiver. If you notice, you can barely make out an unconnected pin. This the the /Rst line to reset the microcontroller for programming. The top right is connected to the rain gauge, and the other wires connect to the anemometer.

    And finally, here is a close up of the finished board. I have done initial testing, and the board works fine. Measures wind speed, direction, and temperature. I haven't attached it to the rain gauge just yet so I am unsure if it works correctly or not.

    The next installment will contain the software to run our new transmitter and I will supply the code. The general outline will be to send ascii text. For example: temperature will send something along the lines of - Temp:24.3

- To be Continued -

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