Tower Pro Micro servo 99 sg90 control

Tower Pro Micro servo 99 sg90 control. 

The inbuilt controller of servo is already programmed with a closed loop control system using a pot. All that required is to give a pulse train with 5% to 10% duty cycle with 20ms as period.

 Most schematics on the internet shows a direct connection between micro controller and servo control pin. That is not correct.

It is required to use a buffer/ current driver for the servo. Use a transistor to connect control pin to micro controller.

The code:

#include<reg52.h>

sbit servo_pin = P1^0;

void delay(unsigned int);

void main()

{

int k,i=0,a[4]={6,12,21,12};

 pin = 0;

while(1)

{

for(k=0;k<100;k++)

{

servo_pin=1;

  delay(a[i]); // a[i] is Ton period  (Ton is precalculated)

  servo_pin=0; // The array a[i] values are calculated to stop the motor at 0, 90 and 180 degrees

  delay(200-a[i]);        //200 represents 20ms(i.e., 200x0.1ms)

}                 //200-a[i] is Toff(=T-Ton=20-Ton)

i++;

if(i==4)

i=0;

}

}

void delay(unsigned int ms)   \\ delay for 0.1ms (tested on oscilloscope)

{

int i,j;

for(i=0;i<ms;i++)

for(j=0;j<11;j++);

}