PIC16F887 ADC servomotor rotation MikroC

Servo Motor

Servo motor is a type of motor that rotate to specific degree assigned by a controller. Some motor rotates within 180 degree, while others rotate up to 360 degree.

A sample of servo motor from Ali Express

This is a high torque motor that could handle some heavy load especially robot arm. It has three wires - two for supply voltage while the remaining one is control signal.

Supply voltage is typically a +5V DC supply from microcontroller board. Its  control signal is a TTL type logic level with a frequency of about 50Hz. Duty time of control signal is between 1.5ms to 2ms that rotate its angle between 0 and 180 degrees.

Microcontroller Interfacing and Programming

Controller needs to generate Pulse Width Modulation (PWM) signal with a frequency around 50Hz, with a variation of high time between 1.5ms to 2ms to rotate this motor. Without using PWM module of controller, programmer can create a software PWM routine instead. However this method has a timing latency.

Simulation of this program

A POT connects to AN0 of PIC16F887 that's channel 0 of ADC module. Controller reads and converts this ADC value into timing value of output PWM signal generates a pin RD0. This pin controls the angle of rotation of servo motor.

MikroC Program:

#define Servo PORTD.RD0
#define Max_Degree 2000
unsigned ADC_Value;
unsigned Servo_Value;
 
void main() {
     int i,j;
     PORTD=0x00;
     PORTA=0x00;
     TRISA=0x01;
     ANSEL=0x01;
     TRISD=0x00;
     OSCCON=0x70;
     ADC_Init();
     while(1) {
     ADC_Value=ADC_Get_Sample(0);
     Servo_Value=ADC_Value/4;
       Servo=1;
     for(i=0;i<Servo_Value;i++)  {
 
         delay_us(1);
         }
         Servo=0;
     for(j=0;j<20000-Servo_Value;j++) {
 
         delay_us(1);
         }
         delay_ms(5);
         }
     }

Click here to download this example from GitHub.