Through PC’s USB port

PC Controlled Robot

Introduction This is the robot whose actions are controlled by pressing

predefined keys over PC.

The controlling signals are passed to robot via USB port of

PC and are received at the serial UART port of the

microcontroller mounted on the robot.

For this a USB2TTL converter is used and serial port

drivers (X-CTU, TTL driver software) are installed over

PC.

Hardware Components Required Microcontroller (ATMega8) development

board

PC with a free USB port

USB2TTL converter

DC motor

Motor driver IC (L293D)

Wheels

Power adopter

ATMega8 Development Board

USB2TTL Converter This USB-to-Serial converter module converts USB signals (3.3 or

5V depending on the jumper setting)

to serial TTL level signals (RX,TX, RTS,

CTS, RI, DTR, DSR and DCD).

The TTL signals are available on a

single-row, 0.1" spaced, though-hole

solder pads. The TX and RX signals can also be accessed via a

mounted male header. Please note that this module converts the

signals to TTL level and not to RS232 level.

The intended usage of this module is to directly connect it to

microcontroller’s Rx-Tx lines to interface it with the USB port of a

PC.

Motor Driver IC (L293D) It is required to supply sufficient

current to motors as microcontrollers

can’t supply that much current.

It is a dual H-Bridge motor

means it can drive two DC

motors simultaneously in both

clockwise and anticlockwise

direction.

Its input terminals are controlled

by the microcontroller.

It also includes the protection

circuit against back EMF.

X-CTU software

This software is used to send the

commands to robot over its USB

Port in ASCII format. These

commands are defined in the

program burnt into microcontroller.

Commands are first operated by

USB2TTL converter which then

passes the commands in serial

form over the microcontroller’s

UART port.

Project overview

To USB port

Serial Outputs

MicrocontrollerUSB2TTL

converter

X-CTU running on PC

Description For designing this robot, PC is first made to be equipped with

required software (X-CTU, TTL driver, AVR compiler and

burner). X-CTU sends commands in ASCII format which are

received at UART port of microcontroller.

The commands are defined in the program burnt into

microcontroller and on getting the specified command, the

microcontroller sends the appropriate signals to the motor

driver IC which in turn make the motor run in forward or

backward direction or take a turn or to stop.