200KHz PWM from 16F877A

Hi,

i want to generate 200KHz PWM from 16F877A or 16F887, kindly advise how is it possible, which crystal i have to use, no very high accuracy is required.

thanking you.

did you take a look at datasheet? how CCP module works? If not then download datasheet of 16F877A and look at chapter 8.0
It is fairly simple...

thanks ajay, yes i read out datasheet also took some reference form book, i understand how to calculate time for timer 2, as this is my first time working for PWM module, i do not understand how do i calculate downwards to get 200KHz PWM, for example how to calculate period if 200KHz reqired, and duty percentage as well, plz help

@ sairfan1
read this section book with examples
download book

http://snk.to/f-cdumgm9t

i do not understand how do i calculate downwards to get 200KHz PWM, for example how to calculate period if 200KHz reqired, and duty percentage as well, plz help

sairfan1

when you say 200Khz PWM then period is 1/(200 * 1000) = 5uS and duty cycle is your decision. if you want a pure square wave then duty cycle is 50% i.e. 2.5uS on and 2.5uS off time for output waveform.

thanks this was helpful to calculate required frequency, how can we calculate maximum PWM possible, for example i have 16F877A at clock 20MHz, how can i calculate maximum PWN can be generated

I told you to read chapter 8 of datasheet. Section 8.3.1 has equation to calculate PR2 value. If PR2 value is not coming into required range then you can adjust using TMR2 pre-scalar. for such a small time of 5uS you do not need to adjust TMR2 I believe. Try it let me know.

thanks, its done.

good job