Electrical Designs
Master Circuit Layout
Utilized to construct the circuit in hardware. On the right is a temporary construction of the design for software design testing purposes.
Printed Circuit Board Design
Designed in Autodesk Eagle, and ordered through Oshpark's Prototype service, this design exactly follows the schematic above, with the exception of pin headers for remote components (food sensor LEDs and CdS cells, and water sensor contacts), and terminal blocks for the motors. All traces are 6 mil width with the exception of the power supply signal as well as all signals around the motor circuitry, which are sized for 2A (as a precaution; motors are not supposed to both be active at once), but only ~1A should be present during motor operation. All empty space on both surface layers contains a ground-plane except the region beneath the Photon's WiFi antenna; this region has been left vacant of all signals inclusive of ground as suggested by the manufacturer.
Top of board, displaying silkscreen guides for soldering.
Bottom of board
Electrical Hardware Designs
Below are brief descriptions of the electrical hardware designs along with their full text design report and subsequent test report.
Astable Timer
This timer design feeds a 12-bit counter, performing a continuous time delay of 12 hours.
This was tested using an external MCU, the Atmega2560, which confirmed the proper 12-hour cycle was functional, with a slight inaccuracy to the timing which can be corrected using the potentiometer.
