# Society of Robots - Robot Forum

## Electronics => Electronics => Topic started by: Zveil on February 28, 2009, 11:10:32 PM

Title: How to count the frequency from IR sensor?
Post by: Zveil on February 28, 2009, 11:10:32 PM
If i want to use an IR sensor to detect speed of car wheel, how do i count the numbers of IR sensor when it is in high level? Got such a thing to count frequency before it sends the data to PIC???
Title: Re: How to count the frequency from IR sensor?
Post by: superchiku on February 28, 2009, 11:13:03 PM
cant understand wat ur saying..do u mean encoders on an wheel and then counting the speed using IR sensor??
Title: Re: How to count the frequency from IR sensor?
Post by: Zveil on February 28, 2009, 11:22:52 PM
I think quite difficult to understand too...sorry ya...erm..i will put an IR emitter outside the wheel, then inside the wheel i will put IR receiver, cos the wheel got rim and it will block the sensor..so got 5 high level and 5 low level when the wheel is rotating for 1 cycle....then i want to count the numbers when the output is high...
Title: Re: How to count the frequency from IR sensor?
Post by: superchiku on February 28, 2009, 11:27:48 PM
look at the society of robots encoders tutorial it is well explained there...now if u get 5 high levels in a certain cycle ..count the time in which u get 5 high levels that is ==one rotation of the wheel and u also know how mich distance the wheel moves in1 rotation so now u can calulate the speed and accordingly use that data
Title: Re: How to count the frequency from IR sensor?
Post by: Zveil on February 28, 2009, 11:32:18 PM
encoders tutorial ah?i thought i should search for the frequency counter...(but i cant get it..) before send the calculated data to 877A..if the output is directly connected to 877A, it is difficult to write the programming code, right??
Title: Re: How to count the frequency from IR sensor?
Post by: superchiku on February 28, 2009, 11:40:11 PM
ok lets clarify one thing....plzzz be clear what u really want if u are attaching ir to the wheel then what do u exactly want to do with it...why do u want to count the frequency...what is the purpose of ur robot ??
Title: Re: How to count the frequency from IR sensor?
Post by: Zveil on February 28, 2009, 11:57:42 PM
oh..sorry ya..i'm weak in doing project one...To count the speed of the car and display on LCD..I thought i need another IC to count its speed before send to 877A... If i want to use IR as speed sensor, i just attach it and connect with 877A? Straight away calculate by programming code??
Title: Re: How to count the frequency from IR sensor?
Post by: superchiku on March 01, 2009, 12:04:16 AM
i strongly recommend to read this .... after reading if u have any doubts post it here

http://www.societyofrobots.com/sensors_encoder.shtml