counter in PIC

[shafiz]

im now taking final project, making an autonomous robot using encoder to determine the distance it has move.
can the PIC act as a counter?

[shahrul]

That is general question, the answer is YES..

[temporary40]

You can use TIMER as counter. You can also use EXTERNAL INTERRUPT and count up at every interrupt. You can also use QEI if you encoder is a quadrature encoder.

[ABSF]

How accurate do you want your distance travelled to be? ARe you using this distance to calculate the speed of your robot?

If the accuracy is not an issue, the method used could be the same as a bike computer. A bike computer uses a magnet mounted on the front wheel spoke. And a reed switch is mounted on the stationary wheel support. When the wheel turns one round, it will be detected by the reed as a pulse on the PIC. So the circumference of the wheel is the distance covered. If more accuracy is required, then 4 or 5 magnets may be mounted and the distance will be 1/4 or 1/5 of the circumference of the wheel. If speed is required, you'll need a RTC to get distance travelled /time spent = Speed.

Allen

[shafiz]

thanks...
the problem is now to program the pic..can somebody tell me how to program pic to make a counter..i preferring to use c programming.please help me!!!

[shahrul]

thanks...
the problem is now to program the pic..can somebody tell me how to program pic to make a counter..i preferring to use c programming.please help me!!!

You want to count the encoder. My way is use RB0 interrupt. You see my example DC Motor.

If you don't want use interrupt, you can use normal code.
But if you do

CODE: SELECT_ALL_CODE

if(RB0==1) counter++;

it's will never working. You should count at the positive edge or negative edge.

CODE: SELECT_ALL_CODE

data=((data<<1)|RB0)&0x03;
if(data==0x01) counter++;


If hard to understand, you just try the code.

[shafiz]

thankz for the reply..but what if i want to use the pic timer as a counter..is it possible?..and how to write the code?thankz again.

[shahrul]

thankz for the reply..but what if i want to use the pic timer as a counter..is it possible?..and how to write the code?thankz again.

Counter timer usually do if you want count specific time. Also can use Timer0 interrupt. You can see example on Timer Module or Timer Interrupt.