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Smart parking


Lizarazo B. Camilocamiloa.lizarazob@ecci.edu.coUniversidad Escuela Colombiana de Carrearas IndustrialesBogotá D.C. – Colombia

ABSTRACT: This document presents the operation of the prototype of an intelligent parking lot with graphic interface, controlling it with the Basys 2 development card, using the VHDL hardware description language. The design, assembly and operation of an automatic parking lot will be presented, which will have a graphic representation on a VGA monitor to simulate the position of the vehicles and the availability of the parking lot; blocking access if there is no longer room for another client.

TABLE OF CONTENTS: VHDL, State machine, H-bridge, FPGA, interface.


One of the most common problems in crowded places, with a lot of vehicular traffic, is finding space to park your car efficiently. It is essential to look for systems that can indicate the current capacity with which they have in real time, the different specialized sites to park and not depend on a person who must give access or not. In addition to this, at the time the vehicle enters, indicating the places available to optimize the time it takes to find a free place, is an added value to the project by helping us with monitors in which we can see the free places in real time.

The implementation of the project will optimize parking times and reduce staff costs, achieving the purpose for which it was designed, generating an advantage of each individual’s time, increasing their availability to carry out their other activities.

II.  Project design

  1. State machine

For the design of the project, we must initially develop the state machine that will govern the behavior of each of the different sensors and actuators present in the prototype. Taking into account that the sensors will be the inputs and the actuators as the motors, to describe the states.

The different states are:

  • E0 – Initial state. No engine running.
  • E1 –  Motor 1 opens.
  • E2 – Motor 1 closes.
  • E3 – Motor 2 opens.
  • E4 – Motor 2 closes.
STATE MOTOR 1 (Entry) MOTOR 2 (Exit)
E0 0 0 0 0
E1 1 0 0 0
E2 0 1 0 0
E3 0 0 1 0
E4 0 0 0 1

Table 1: Motor states

Table 2: State transition table

E0 0 0 0 0 0001 E1 1 0 0 0
E0 0 0 0 0 0100 E3 0 0 1 0
E1 1 0 0 0 0010 E2 0 1 0 0
E3 0 0 1 0 1000 E4 0 0 0 1

Illustration 1: State diagram

  1. Description of the chosen electronic components

Basys 2 Card: It is a development card that includes an integrated FPGA which can be programmed with the help of the VHDL hardware description language. It is necessary to know the syntax of this description language since it is a text-based language. The Basys2 board is a circuit design and implementation platform that anyone can use to gain experience in the construction of real digital circuits. Based on an Xilinx Spartan-3E field programmable gate array and an Atmel AT90USB2 USB controller, the Basys2 board provides complete, ready-to-use hardware suitable for hosting circuits ranging from basic logic devices to complex controllers. A large collection of built-in I / O devices and all the required FPGA support circuits is included, so you can create countless designs without the need for any other component as actuators, from now on the implementation phase begins) .

Illustration 2: Basys Card 2

Bridge H:

Illustration 3: Bridge h

On the other hand, to control the direction of rotation, we only have to reverse the direction of current flow through the motor, and the most common method to do so is by an H-bridge. An H-Bridge circuit contains four switching elements. , transistors or MOSFET, with the motor in the center forming a type H configuration. By activating two particular switches at the same time, we can change the direction of the current flow, and thus change the direction of rotation of the motor.

So, if we combine these two methods, the PWM and the H-Bridge, we can have complete control over the DC motor. There are many DC motor controllers that have these characteristics and the L298N is one of them.


The electric motor is a machine that is responsible for converting electrical energy into mechanical energy through the action of the magnetic fields produced by its coils.

Direct current motors have several differences since they are constructed differently compared to those of alternating current. One of the main differences is that they can work in reverse, that is, they cannot only be used to transform electrical energy into mechanics. They can also function as electricity generators. This happens because they have the same physical construction as the generators.

DC motors have a high starting torque compared to AC motors. They are also easier to control speed, so they are effective in applications where speed control is required. They are used for elevators, trains, trams, electric cars and all those applications in which a constant speed control is required.


Illustration 4: Operating torque diagram E-R

Normally two different types of optical sensors are used in the microbots, one is the CNY70 which is an infrared optical reflection sensor, that is, the sensor is composed of a transmitter and a receiver encapsulated in a single component, both are aligned so that the receiver can receive the reflection of the emitter when it hits a surface.

The emitting diode consists of two terminals, the anode (A) and the cathode (K), the receiver has the ability to conduct a current flow between its emitter (E) and the collector (C), the amount of current that can Flow through it is proportional to the amount of light that falls, the surface to which the sensor points must be within a range of 3 and 5 mm maximum to obtain a constant reading and that can be interpreted correctly by the microcontroller.


Illustration 5: Prototype implementation

Finally, after having an elaborate design, we proceed to make the respective implementation of our automated parking lot taking into account the correct position of the sensors and actuators, resulting in the assembly shown in illustration 4.


  • We can see how useful the cards that contain FPGA’s to be for digital development projects become, small projects such as this prototype or projects can be made in which all the NAND gates of the card are fully used.
  • It is important to keep in mind that this is a control card, that is to say that the respective assembly must be done to decouple the earth from the card with the earth from the source that moves the motors or actuators, both for its protection and for insufficient power to support the load of these.
  • The implementation of projects with digital logic does not open up a greater vision of the innumerable possible solutions to everyday problems.


[1] Henley Court Pullman, FPGA Board Reference Manual, https://reference.digilentinc.com/_media/reference/programmable-logic/basys-2/basys2_rm.pdf

[2] Turmero Pablo, Máquinas de estados finita, https://www.monografias.com/docs114/maquinas-estado/maquinas-estado.shtml


  1. Andrés Lizarazo Bahamón, Born in Bogotá on October 11, 1987, a student of the ninth semester of electronic engineering at ECCI University, at a professional level he completed his studies in Telecommunications Technologist, he works as a software developer at his company Dipzo Co.
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