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Check my code for controlling servo motors using PIC16F877A

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hello
I face problame in controlling servo motor
I use pic16f877a programming by mikroC
I need the motor to move (0 , 90, 180) degree is the following code correct or not??
if not please help me as soon as possible
Code: 
void main() {
portc=0b00000100;
trisc=0b00000000;
PWM1_Init(5000);
PWM1_Start();
PWM1_Set_Duty(255);
delay_us(1500);
PWM1_Start();
PWM1_Set_Duty(255);
delay_ms(2);
PWM1_Start();
PWM1_Set_Duty(255);
delay_ms(1);

}

thank you
 

Re: control servo motors

did you include the pic header file?
 
Re: control servo motors

I don't include pic header file
I also load different program without header file and work perfectly
any other advice??
 
Re: control servo motors

you should also tris first before port. Tris will set the i/o to whether it is input or output. Port will set te initial values to the respective port. =)
 
Re: control servo motors

thank you john blue
but it doesn't make any different
just move to 45 degree and stuck there
any other suggestion please:???:
 
Re: control servo motors

Try setting this: PWM1_Set_Duty(255); with different value

---------- Post added at 02:38 ---------- Previous post was at 02:36 ----------

Here is one sample:

// microcontroller : P16F877A
// PWM module is set on RC2 Pin No 17.

unsigned short i;

void main() {
PORTC = 00; // Set PORTC to $FF
TRISC = 0; // PORTC is output
Pwm_Init(5000); // Initialize PWM module

Pwm_Start(); // Start PWM

while (1) { // Endless loop
for(i=0;i<=255;i++)

{ Pwm1_Change_Duty(i);

delay_ms(10); }

} }
 

Re: control servo motors

thanks john blue for trying to help me
I appreciate that,but i try the sample code that you post and give me same as the before result .
I try different code without PWM it give me good result
Code: 
void main() {
trisb=0b00000000;
while(1)
{
portb=0b10000000;
delay_ms(2);
portb=0b00000000;
delay_ms(20);
}
}
but if i use delay_us(2500) instede of delay_ms(2);
the servo motor not set on constant posetion and keep moving
any idea please??
also thanks alote
 

Hi

I do not program in C, but I do work with RC and servos.
Most servos have range of control from 1ms to 2ms with 1.5ms being the middle settings. (some can operate slightly outside these ranges). I would say that your range of 2500us could be outside the scope of the servo.

They normally have a complete cycle of 20ms (include PPM pulse).

I do not know if that will help.


John
 

thank you foa all
but until now I don't have solution :(
 

Re: control servo motors

Code: 
void main() {
trisb=0b00000000;
while(1)
{
portb=0b10000000;
delay_ms(2);
portb=0b00000000;
delay_ms(20);
}
}

i think why it keep moving because your code is repeat the cycle..
use some "if" command and at a button switch to your hardware temporarily to try your code..
 

Re: control servo motors

Hi

I do not think the repeat is the issue, that is the way servo's work. They normal operate with complete cycle of 20ms, in a normal rx setup. Try dropping the second delay to 18ms in the code example to see if that resolves it.

You might see a slight jitter depending on acturate your clock is.
 

I try all advice
and at the end I think the power supply is the problem
but other problem is I can't reach 0 and 180 degree and I can reach 90 if the delay=1500 us??
I'm very happy when I see someone try to help me
thanks alote for everyone
 

Hi

The delay for 0 is 1000 us and 2000 us for 180.

HTH
 
thank you cubanflyer
I do what you said but I don't reach what I want
I think I keep the servo in the position it reach and complete the project
 

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