Hardware Specification
Power Supply
Power is supplied to the main board by an Xbox360 power supply. The standby pin is tied to +5V causing 5V and 12V to constantly be supplied along their respective wires. The power enters the board through a RJ11 jack. Pins 4-1 are +5V, GND,+12V, and GND respectively.
Central Command
The COGITO Project receives all of its commands from a MySQL server and thus it needs a gateway to connect to the internet. Due to the project’s low cost budget and need to access MYSQL the microcontroller does not connect to the internet itself. The wireless desktop is connected to the internet and then through a bridged connected shares it connection to the laptop. The laptop is responsible for checking the MySQL database and sending such commands to the board via a PICAXE USB-Serial Cable. This cable is also used to program the PICAXE40X2. The PICAXE40X2 receives its commands from the serial connection and then through the I2C interface, sends its commands to the ATMEGA644P. The ATMEGA644P is clocked by a 16 MHZ crystal. The peripherals are connected directly to PORTA. A green led is lit whenever power is supplied to the board.
Peripheral Communication
All devices follow a standard interface. Pin 4 of the RJ11 plug is +5V. Pins 3 & 2 are signal 1 & 2 respectively. Pin 1 is GND. On 12V devices all pins are laid out the same except 12V is used in place of 5V for both general power and signal communication.
AC Block Unit Relay
This unit has a port that is used to control a dual color status led and another port that is used to control the physical relay. The relay then connects to a power strip where several high power devices can be connected.
AC Unit Relay
This unit is used to control less powerful devices but with the ability to control which ones turn on. A green led is placed in series between both signal lines and their respective relay.
Emergency Lights
The emergency lights are a 12V unit peripheral that consist of a pair on cold cathode lights controlled by signal 1 and a orange status light controlled by signal 2.
admin | 
November 9, 2010 2:57 pm
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