help with PWM circuit for PIC16f877A

[toto_na16]

help with pwm and PIC16f877a

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Hi all

I want to generate 500 Hz clock using PWM module in PIC16f877a

so i wrote this code in mikroC but I get no output on the oscilloscope

void main(){
     TRISC.f2 = 0;
     pwm1_init(500);
     pwm1_start();
     PWM1_change_Duty(127);

     while(1){}

    }

I am using 8MHz oscillator

so please anyone help me doing this ??

 

[Tahmid]

help with pwm and PIC16f877a

Hi,
I've also faced this problem earlier. I don't know why this happens, but if you use 18F series PIC this problem does not occur.

Hope this helps.
Tahmid.

 

[Tahmid]

Hi,
I didn't see the earlier post. Guess I missed it.
Check this for tutorial: https://www.mikroe.com/en/books/picbasicbook/00.htm

For interfacing to LCD, look under the help menu in the LCD part. Details are given there.

Say, if you have a variable that stores the value of the duty cycle(255 for 100%, 0 for 0%, 128 for 50%), this is in 8-bit "byte" or "char" data format.

To send this to LCD, you have to convert this to string using this:

   dim txtDuty as string[3]
   dim Duty as byte 'Holds duty cycle
   dim Duty16 as word
   Duty16 = (Duty * 100) >> 8
   Duty = Duty16
   ByteToStr(Duty, txtDuty) 'Converts byte to string and stores in txtDuty
   LCD_Out(R, C, txtDuty) 'Replace R by desired row no and C by desired column no
'On LCD, a value on a scale of 100 will be shown

For initialization of LCD, it depends on compiler version. This is available in the help menu.

Hope this helps.
Tahmid.

 

[alexisjm_04]

Can any one help me?
I got a servo motor,16f877a,20MHz xtal,PICC compiler,I have a burner for my PIC and I use C when writing a program. I got a 5k pot connected to pin A0 and I am planning to use port D to control the servo to go left and right when I turn the pot. The problem is I don't know how to start .... I really wanted to learn more about the MCU and I tried blinking LEDs an and using push buttons before, I hope that someone can help me with complete codes, Thanks in advance!!

 

[switimira]

Hi Tahmid..hope you notice this reply,
can you help me correct the programming below.ican't compile it..it is from earlier that i want to make variable duty cycle..hope you will help..thanks in advance

program 1
x var byte
TRISC.2 = 0 ' CCP1 (PortC.2 = Output)
PR2 = 110 ' Set PWM Period for approximately 45KHz
CCPR1L = 55 ' Set PWM Duty-Cycle to 50%
CCP1CON = %00001100 ' Select PWM Mode
T2CON = %00000100 ' Timer2 = ON + 1:1 prescale
Main:
if PortA.0=0 then wait0
Pause 500
if PortA.0=1 then wait1
Goto Main
wait0:
CCPR1L=0' reset PWM duty cycle
end
wait1:
CCPR1L=x+6' increase PWM duty cycle by 20% each time the push button is press
end.

Added after 7 minutes:

i mean that each time the push button is press or active low,,,it will reset the duty cycle..and when the push button is release the duty cycle will increase 5 percent up to 80% duty cycle..then if the push button is press again after 80% ,the duty cycle will back to 50% and this process will go on.