In this the robot control using PC/Laptop .in this project we learn about how to work on Serial communication.

1. PC Controlled Robot
Through PC’s USB port

2. 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.

3. Hardware Components Required
 Microcontroller (ATMega8) development
board
 PC with a free USB port
 USB2TTL converter
 DC motor
 Motor driver IC (L293D)
 Wheels
 Power adopter

4. ATMega8 Development Board

5. 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.

6. 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.

7. 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.

8. Project overview
USB2TTL Microcontroller
converter
To USB port
Serial Outputs
X-CTU running on PC

9. 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.