can we rotate a servo motor to the required angles such as 45 55 degrees

Hi Sudheer!

Sudheer kumar Vuppula said:

i want to rotate a servo motor

What do you mean by "servo motor"? A real motor or one of those R/C servos?

Sudheer kumar Vuppula said:

predetermined angles

In the case you're talking about one of those R/C servos, this isn't a problem at all. They expect a PWM input signal with a period of 20ms and a pulse with varying from ~1ms to ~2ms for ~180° movement:

But they cannot rotate, only like this:

The input signal can easily be generated by a timer module and OUTMOD_7 - here is an example generating the required pulse:

The only thing you need to change is

TA0CCR1 = 1500; // Duty-cycle: 1000 = ~1ms, 1500 = ~1.5ms, 2000 = ~2ms

Since every servo behaves a little bit different, you might need some sort of calibration to find the exact values. Once you found them you can work with a formula like this:

#define PWM_VALUE_0_DEGREE     1000
#define PWM_VALUE_180_DEGREE   2000

void update_servo_angle( uint8_t degree )
{
  if( degree <= 180 )
  {
    TA0CCR1 = (PWM_VALUE_0_DEGREE + ((PWM_VALUE_180_DEGREE - PWM_VALUE_0_DEGREE) * degree) / 180));
  }
}

You can expect the servo to behave nearly linear. If not you can also add some more calibration points for 0, 45 and 135 degree, for example.

If this is not what you're looking for, please describe your application a little bit more in detail.

Dennis

If you want precise angles, then you need some sort of positional feedback signal from the motor to the MSP. Maybe if you were a little more specific, including the make/model of the servo motor and how you intend to connect it you would get better feedback from those here on the forum.