Weather station with pressure reading, relative humidity, indoor & remote outdoor temperature display.Both Celsius or Fahrenheit & mbar/hPa or mm Hg supported. With calendar & clock. Easy 3-button user-menu. 42 hour-history display (curve). Auto-memory & display of all high and low-values. PIC 18F452 running at 4 MHz, power saving sleep mode. Sensors are only turned on when needed..
Now this was a huge project! All sensors had to be fully tested one at a time, wireless communication had to be perfect, various LCDs were tried. Nevertheless, here's the result: hope you enjoy it!
The circuit may be powered by a small 9V battery, but you'd better take a couple of AA-batteries. A 6-pack will last a several months. Consumption for the base station is around 8 to 9 mA whilst active and only 2 to 3 mA in sleep mode (LCD remains on.) The transmitter takes slightly less.
The receiver (base station) is active during 5 seconds & then goes to sleep for 45 seconds. The transmitter takes a nap every 30 seconds or so.
Menu mode is entered when pushing the "menu" button (what's in a name?) for 1 second. Browsing & value changes are done with the "min" & "plus" keys. When in normal mode (like in the picture above), the "min" and "plus" keys can browse through the different histories. All these controls will wake up the processor if it was in sleep mode.
On the left-hand side of the LCD we have (from top to bottom :) Outside temperature, Pressure, inside Temperature, Relative Humidity, Calendar and Clock.
On the right: High value of the past 42-hours, Bar graph histogram (right is most recent value), Low value.
All sensors are read & LCD (left-hand side) are updated every 50 seconds. Histogram is updated on the hour (e.g. 10h00, 17h00, 22h00,...). All data is stored in EEPROM and is loaded at power-up. In case of a power failure (or when changing batteries), there will be no data (nor history) lost.
Schematics: right-click & "save picture as" for full resolution or (recommended) download the eagle-file below.
Remote temperature sensor (transmitter) compatible with HUGER & OREGON SCIENTIFIC remote sensors
Parts Lists (Bill of material):
For the base-station (receiver:)
For the remote temperature sensor (transmitter:)
PCB ScreenshotsBase station (receiver:)
Remote transmitter (outside temperature:)