I want to use sonar to find distance in my robotics project which uses a PIC18F452.The diagram of the circuit is attached below (Which I found from the web). But the resource I found it says I have to use PWM to drive it.Unfortunately I am already using my PWMs for motor controlling. So can anybody tell me how to use it without PWMs alongside my program.(I'm using mikroC language.)
Being new to PIC I don't know much about timers as well.
Thanks in advance...

 

So use another microchip MCU for for the sonar range, and find a way that the two MCU can communicate.

 

t06afre thanx for the suggestion. but I can't afford 2mcus.(I'm using a readymade robot board. and it may be complicted.) Is there any way I can use 555 IC for the purpose? (I've seen it in IR proximity sensors to generate a 38KHz signal.)

 

You should be able to use a 555 for the PWM for the sonar transmitter. The reciever data can be interpreted by the uC.

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Here is a circuit using 555 for transmitter.
http://english.cxem.net/home/home44.php

The reciever is set as a switch, but you should be able to finagle the circuit to do what you want.
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