Frequently Asked Questions
1) What exactly to I need to order to build a complete µWeather weather station?
To build a µWeather weather station, you need to get a PC Board, programmed microcontroller, sensors, a set of common components (resistors, capacitors, etc.) and optionally a 20x4 HD44780 LCD display unit.
The PC Board is available for sale through the µWeather web order page at http://www.qth.com/RXcomm.
If you have the capability to program a 16F877 microcontroller, the most recent firmware for µWeather is available for download free at the project web page. If you are not able to program the microcontroller, and wish to purchase one preprogrammed, these are also available at the web order page. We stock microcontrollers rated for two different temperature ranges: -45°C to +125°C (industrial temperature range) for µWeather stations deployed outside in northern climates and 0°C to + 80°C (commercial temperature range) for µWeather stations deployed indoor or in southern climates.
Honeywell HIH-3610-001 humidity sensor chips are available for sale at the project web page. They may also be available at Allied Electronics and Newark Electronics, however in my experience the lead time for ordering this part has been about 8 weeks. As a result, we will try keep a few of these humidity sensors in stock. Part numbers and ordering information from these two firms are listed on the parts list included in the latest zip file available on the downloads page.
Motorola MPX4115A barometric pressure sensor chips are also available for sale on the project web page. They are also available, in my experience with some lead time, from Allied Electronics and Newark Electronics. Part numbers and ordering information from these two firms are listed on the parts list included on the downloads page.
Dallas Semiconductor DS1621 or DS1624 temperature sensing chips (either one will work) as well as the DS1307 real-time clock chips are available for sale at http://www.maxim-ic.com. They also have a free samples program if you qualify with details listed on their web page.
Common components such as the op-amp, voltage regulator, resistors, capacitors etc. may be available in your junk box. µWeather has been carefully designed to use common, widely-available components. If you wish to order a complete set of these components from Digikey (web page http://www.digikey.com), the Digikey order numbers for each part are included on the downloads page. I have also created a Digikey order form for a complete set of the common components that you can simply print out and mail to Digikey (along with the required remittance) to place your order.
The 20x4 LCD display is optional - µWeather will work equally well with or without it. If you plan to deploy the µWeather station remotely, you can save a few dollars by not adding the display to the µWeather station. In fact, at colder temperatures, the LCD display will not work and should not be installed. However, if you plan to operate the µWeather main board indoors, with sensors placed remotely, an LCD display may be a useful thing to include in your project. Suitable 20x4 LCD's are available at Digikey, however they are usually available surplus at places like http://www.mpja.com or http://www.allelectronics.com for significantly less cost. Just be sure to get an HD44780-based display and not a serial display.
Obviously, prices from parts suppliers change with time, however on the date that this answer is being written (12/26/01) the cost for the various components are: PC Board - $12, programmed microcontroller - $15, humidity sensor - $25, barometric pressure sensor - $19, temperature sensor and clock - $6, complete set of common components from Digikey - $28, and an optional LCD display $15. The total cost of all of these items is approximately $105 plus shipping if you don't include a display or $120 plus shipping if you do include a display.
This kind of information is available on the project web page at http://www.RXcomm.net/downloads.htm. The download files are in ZIP format and will require a utility such as WinZip in order to uncompress them.
5) I see that your future plans are to add rain data to the µWeather station. What kind of additional hardware will I need to have in order to take advantage of this upgrade? When will it be complete?
We are planning to add rain monitoring to the µWeather station by using rain gauges that emit a single 5V TTL pulse for each 0.01 inch of rain. There are several commercially-manufactured gauges that meet this standard, as well as a couple of homebrew raingauge projects out there on the web. The rain development work will be done with a PEET Bros. electronic rain gauge. We don't expect that any modifications to the µWeather station pcboard will be required to accomodate the rain gauge.
At this point, the completion date for this rain data upgrade is anticipated to be March 1. Stay tuned to the project web page for further details and announcements. [I've been swamped at my real job, so this isn't finished yet. It should be shortly! - Dave]
You can use the datalogger output of µWeather to add regular weather reports to your Kantronics digipeater. In addition to µWeather and the Kantronics TNC, the only additional equipment required is a null-modem serial cable to connect between the TNC and µWeather. In order to use µWeather to add weather reports to your digipeater, make the following changes to your Kantronics TNC configuration (the TNC must be running 8.2 or later firmware):
1) Set the abaud routine to 2400 baud with the command:
This sets the TNC up to receive weather data from the µWeather datalogger serial port output at 2400 baud.
2) Put proper station position data in the LT 1 buffer. You have probably already done this in order to place your digi on the map. If so, it does not need to be changed other than perhaps to add the weather symbol. Use the following format:
LT 1 !4151.96N/09127.36W_
Be sure to substitute your station's position information instead of that given in this example. You can add comments or other data (such as PHG) if you wish after the underscore.
3) Set the path for both the position data (LT 1) and the weather data (this will be in LT 2). Although these can be set independently, they should probably both be the same in order to provide the same coverage.
LTP 1 APRS VIA WIDE3-3
Use whatever path is appropriate for your location.
4) Set the transmission time for the position and weather data.
BLT 1 E 00:30:00 START 00:00:30
5) Use the GPS buffer to load weather data from µWeather
GPSHEAD 2 !!
This tells the TNC to load the LT 2 buffer with weather data.
6) Set up the GPS buffer interface.
This sets up the TNC so that it will load the GPS buffers.
7) Connect the µWeather serial port to the Kantronics TNC serial port via a null-modem cable and power cycle the TNC.
After completing these steps, the TNC will continue to digipeat as before, and in addition will transmit weather data every 10 minutes. If you want to send weather data along two distinct paths, you can use the LT 3 and LT 4 buffers in a similar fashion as illustrated for the LT 1 and LT 2 buffers above.
When you want to return to INTFACE TERM mode, unplug the null-modem cable, connect a terminal to the TNC with a standard serial cable, and type three (3) cntl-C's in rapid succession (be sure your terminal is set for 2400 baud). After a few seconds the TNC will return to INTFACE TERM mode.