NEED HELP FOR HARWARE PWM USING PIC

[mohan_200484]

hi every body.
Nowq i need help in designing Hardware PWM using PIC16F877. pls help me. i have read the data sheet. i ahve made a code and connected to a motor but i could not find the difference.

 

[jshroff]

What do you mean you could not find the difference, you are going to have to be a bit more clear in your question if you expect people to help you.

Is the PWM working or you are having problems just getting the pwm.

1. Show what registers you setup for the hardware PWM.
2. What pin are you using to output the PWM?
3. Did you remember to make tyhe pin an output?

 

[mohan_200484]

sorry for the delay. i was busy with another work. PWM i used is software pwm. now it is working fine. but now i need to control the speed of the DC motor using hardware pwm. i have prepared H-bridge circuit for that. i have also tested it. it is working fine with software pwm. now i need to change it to hardware pwm.pls guide me.

 

[IanP]

One of the simplest PWM circuits can be based on the very popular 555 timer ..
Here is an example:
**broken link removed**
Depending on your H-Bridge configuration, you may need to invert the output to provide 2-signals shifted by 180°, but this can be easily done with CMOS gates ..

Regards,
IanP

 

[Bassem_fahmy]

Hi,
to control the speed on a dc motor u'll need a kind of feed back, a tacho meter or simply opto interupt, count the pulses and hence get your speed, then control you pwm according to speed.