HC SR04 and Servo with the Obstacle Recognition code I created and wrote an FPGA project on this video for the Altera DE0 Nano.
We wrote the FPGA code with verilog HDL, which detects objects at a distance of 20 cm and allows the servo to move or stop.
If there is an object at a distance of 20 cm, the servomotor stops, and if there is no object, servo moves.
Code: https://goo.gl/kmgQqP