2 square waves 1 pic

B

bee

Member

• Mar 21, 2013

• #1

Is it possible to output a 457khz square wave and another wave in the hz region at the same time , With a 12f675 and mikro c , I thought about interupts but that stops the original operation,

Regards
Bernie

 

Jon Wilder

Active Member

• Mar 21, 2013

• #2

The interrupt would be so short you'd never notice the original operation stopping. It would occur too fast to be human perceivable.

 

P

Pommie

Well-Known Member

Most Helpful Member

• Mar 21, 2013

• #3

Nope, not possible. Use a faster chip, the 12F675 with a 20MHz crystal will have only 5 instructions between changing pin states and that will only give you 500kHz, not 457kHz.

Mike.

 

ronsimpson

Well-Known Member

Most Helpful Member

• Mar 21, 2013

• #4

some PICs have a NCO that might do the job.

Application note TB3071 shows using a NCO to get frequencies in the range of 16 Hz to 500 kHz using a PIC10F322,

 

B

bee

Member

• Mar 21, 2013

• #5

Thanks for the replys , I have been on google most of the day and didnt find much , I will try it with a interupt in the code , as i only have 12f675 on hand , If no good will lokk at a faster/ different chip

B


ps ;Ron i just googled (NCO) that could work

 

Ian Rogers

User Extraordinaire

Forum Supporter

Most Helpful Member

• Mar 22, 2013

• #6

You can run the pic with a 475khz external clock source... Then do the other frequency with a timer... OSC2 can output the 475khz and any other pin can do the slower frequency...

 

B

bee

Member

• Mar 23, 2013

• #7

Thanks fellas
I got it working with a simple if loop the program worked but still not good for transmitting , Back to the drawing board

Bernie