Raspberry Pi 3 Development System
This is the development system I used to write the code for the alarm system. The code was later tested using a Raspberry Pi Zero W system.
Main Board
Blog Three: Adding Additional Ports The following blog contains some ideas and suggestions for improving your alarm system. The MCP23017 I/O Expander: The expander board is based on the MCP23017 port expander integrated circuit. The device comes with sixteen ports which can be configured as either inputs or outputs. The I/O Expander Board: The proposed expander board will have eight inputs and eight outputs. The inputs are identical to the ones on the main board and come with the same antitamper features. The eight outputs of the IC are connected to solid state, optically isolated relays. Each relay is capable of sinking twenty four volts at two amps, or forty-eight watts. This should be more than enough to drive mechanical relays, solenoids or relays. Figure 9- 1 . Port Expander IC Figure 9-1 shows the connections to the MCP23017 port expander IC. Connectors J1 and J2 connect to the I2C bus which provides powe...
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