A computer is used to control the ON/OFF switch of two power sockets with PIC18F4550 through the USB port.
The USB was chosen to work with the PIC18F4550
microcontroller because the 500mA power supplied by this port without any additional power supply is enough to activate a relay. High voltage electricity is involved in this project so it is advised that proper handling must be observed especially when not comfortable with basic concepts of reading schematics, induction, and AC and DC electricity.
These devices always represent a risk of mechanical failure despite the high voltage part of the
circuit being virtually isolated from the controller circuit by relays.
To control the relays, the same as USBDAQ but two identical sub-circuits were added. The SIXCA USBDAQ is the basis of the firmware which is very easy to use. To turn ON/OFF the digital outputs that control the relays, a very simple set of ASCII commands is implemented.
In order to generate the 500mA with the host, the bMaxPower had to be adjusted. The name USocket was used to change the vendor ID and name. The PCB is divided by 3 boards.