some quations about a simple robot

i want to make a robot which detect walls and chooses the correct path.
robot's micro controller and complier will be Atmega32L , codevision.
four IR sensor will be wall detectors.
here is the circuit of IR sensor
**broken link removed**
my problems:
1.the range of IR sensor is too short it can only detect thing closer than 20 cm (if i use 5mm photodiode LED receiver )
how can i increase the range up to 1Meter
or its better to use ultrasonic sensor as distance meter???
(if yes could you tell me how can i use this sensor with atmega 32 and can i use 2 sensors on one atmega 32??)
2.what is the best xtal's frequence for atmega32 in order to run the program quickly??
3.how can i drive 2 motors, control the speed of them and change the rotation orientation easily??(lm298??? if yes could you learn me how?)
sorry for my bad english
thanks for your guidance

If you can find this book ...
**broken link removed**

In the chapter on interrupt handling, there is one problem/outline for setting up an echo sounding range finder, using an ultrasonic transmitter and receiver pair.
It is suggested that the ultrasonic range is 2.5 m, with a resolution of 1 cm. You might have to read more of the chapter to fill in the details ....

This material is definitely in the first edition of the book. I am not absolutely sure about the second edition. .... It seems like the general idea could be transferred to the micro that you have chosen. ....

i found ultrasonic modules
but i dont khow how use this modules?
4 pins= 5 volt gnd T and R
what is the T and R pin???
i think if connect 5 volt to T pin for a while after echo the sound the R pin give me 5 volt
correct???

Nimra said:

i found ultrasonic modules
but i dont khow how use this modules?
4 pins= 5 volt gnd T and R
what is the T and R pin???
i think if connect 5 volt to T pin for a while after echo the sound the R pin give me 5 volt
correct???

Click to expand...

Maybe it is something like this:
**broken link removed**

can you give me some info about "l298" and datasheet
how it works?

l298 seems to be popular on this site ....
I haven't use it ..... I have used an Allegro stepper controller ....
**broken link removed**
Very simple to use ..... just set up the logic for what kind of step you want, and then input a pulse for each step .....
Actually I used the Allegro 5804, but that is no longer available.
I think the A3977 has greater power handling.

i am studing about the auto robot that is i am working on that sub please send some information about that

i have the data sheet of L298 and i give you
you can contact with me at
zahidabbas25@yahoo.com
i will help you because i made the line follower robot
i belong to pakistan
NIMRA