The Microchip microcontroller PIC16F877A©
generates impulses on ten pins (PORT D and two pins
from PORT C) which are triggering relays. Signals from
relays are used to stimulate the movement of the DC
motors implemented inside of joins of the robotic arm.
For every degree of freedom (DOF) two pins of
microcontroller and two relays are assigned (pins RD0
and RD1 for base, RD2 and RD3 for shoulder, RD4 and
RD5 for elbow, RD6 and RD7 for wrist and RC0 and
RC1 for fist).
Depending on the state of two pins, there are four
situations: