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| February 09 2010 12:42:01 | |
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Weather Station· Santosh on May 14 2008 09:24:01
 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.. Circuit Explanation: 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.  Base-station (receiver)
 Remote temperature sensor (transmitter) compatible with HUGER & OREGON SCIENTIFIC remote sensors
Parts Lists (Bill of material): Receiver, Calibration: Pressure calibration Make sure you're using a reliable multimeter, and not a cheap one. First adjust VREF- (PIC RA2, pin 4) to 2V40 with trimmer R9. Then adjust VREF+ (RA3, pin 5) to 4V70 with trimmer R8. At last, do a manual (linear) pressure correction via the menu (see below.) Of course, you'll have to know the current pressure for your area ... but this is just once! Humidity calibration: Make sure you're using a reliable multimeter, and not a cheap one. First adjust VREF- (PIC RA2, pin 4) to 2V40 with trimmer R9. Then adjust VREF+ (RA3, pin 5) to 4V70 with trimmer R8. At last, do a manual (linear) pressure correction via the menu (see below.) Of course, you'll have to know the current pressure for your area ... but this is just once! Temperature calibration: No need, the TC77 sensors are fully calibrated. Downloads: WARNING: may not be duplicated for any commercial use whatsoever without explicit consent from the author (c) Michel Bavin For the base-station (receiver:)
For the remote temperature sensor (transmitter:)
PCB ScreenshotsBase station (receiver:)
Remote transmitter (outside temperature:)
Info and Data sheets
Tools This project is made with the PCWH CCS compiler ($500,-) You can install Microchip's free PLAB IDE with it to get things going smoothly. Programming of the PIC18F452 was done with the excellent Tiny PIC bootloader, through the RC6 & RC7 pins. But you'll need a regular PIC programmer to write the PIC the first time with... The remote transmitter has software RS232 on pins 9 (RB3,TX) and 10 (RB4,RX) for debugging only. Eagle 4.11 was used for the schematic & PCB layout. 8 Comments · 28646 Reads
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· 08. Future developments · 07. Applications of ... · 06. Security · 05. Standards ShoutboxYou must login to post a message. 09/02/2010 09:08 Time to learn some PIC18 asm
07/02/2010 09:16 You must be very preceptive. I've been runnng Fedora 11 for months now. MPLab's IDE doesn't work 100% installed via wine everything installs fine minus a few legacy lanuage tools i believe
06/02/2010 18:40 Well try Fedora then. Its easy...
06/02/2010 11:33 I wish I could get linux to recongize my Pickit 3 being connected, MPlab works fine but so close argh
03/02/2010 07:19 Sup fellas
02/02/2010 14:35 Thanks....IronBrai
n 02/02/2010 09:07 Congratulations! I have 2.5 years left of my computer engineering degree, I thoroughly enjoy what I am learning but all this work is quite overwhelming.
02/02/2010 08:25 My exam of final semester is coming after 15 days... need to prepare more...After that I am going to be an Engineer....hehehe
he 02/02/2010 08:24 Thanks ironBrain...
02/02/2010 07:53 I like this site, new guy here. Hope to make some friends
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full parts list?