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[hw/greenhouse] / README

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-Greenhouse Shield for Arduino
+Greenhouse Board
 
-This is a board my son Robert is building to monitor and control conditions 
-in our back yard greenhouse.  The objective is a "shield" for an Arduino
-Duemilanove board, with the following features:
+This is an accessory board for a Raspberry Pi, designed to add a real time clock, sensors, 
+and relay control.  The clock allows event scheduling even if there's no network connection,
+though we anticipate having our greenhouse on the net full time.
 
-       - temperature sensor                            MCP9700A
-       - light sensor                                  PDV-P9007
-       - humidity sensor                               HCH-1000 + TLC555
-       - i2c real-time clock                           DS1307
-       - i2c non-volatile memory for data logging      24AA1025
-       - 4 relay-switched mains (110 volt AC)
-               - electric heater (high current!)
-               - electric fan
-               - hydroponics pump
-               - spare
-       - spi TeleDongle interface for RF link
-               http://altusmetrum.org/TeleDongle
+The sensors include barometric pressure, temperature, and humidity using an MS-8607, and
+a light sensor using a photocell and associated ADC.
 
-The idea is that we log temperature, light, and humidity every so often to
-the non-volatile memory with timestamps.  On each sample, we check current
-conditions and turn the heater on if it's too cold, and the fan on if it's
-too hot.  The hydroponics pump gets turned on and off on a regular schedule.
-And the RF link provides a mechanism for remotely downloading the logged data,
-changing setpoints and schedules, manual override, etc.
+There are 4 GPIO-controlled AC relays with LED state indicators.
 
-References:
-
-    various relevant circuit fragments:
-       http://www.ladyada.net/learn/sensors/cds.html
-       http://klk64.com/arduino-spi/
-       http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1264143673
-
-    pcb layout in gEDA of an Arduino shield:
-       http://lowvoltagelabs.com/products/videooverlayshield/
-
-    5 to 3.3 volt level shifting with a MOSFET ...
-       http://www.rocketnumbernine.com/2009/04/10/5v-33v-bidirectional-level-converter/
+The basic idea is to log environment conditions, present them over the web, and use the
+relays to automatically control heating and cooling systems to regulate the environmental
+conditions.