MSP430G2553 motor speed control with a potentiometer

[SirPatrick 35]

This code just controls the speed of a small 3V DC motor on P1.2. The speed is controlled by a potentiometer on P1.1. Feel free to suggest improvements as I am new to the MSP430.

 

#include 


#define motorPin BIT2
#define analogInPin INCH_1

void initADC();
void stopWDT();
void initTimerA();

long map(long x, long in_min, long in_max, long out_min, long out_max);
int analogRead(unsigned int pin);



void main(void)
{
 volatile unsigned int potentiometerValue;

 stopWDT();
 initTimerA();
 initADC();
 for (;
 {
   potentiometerValue = map(analogRead(analogInPin),0,1023,0,1000);
   CCR1 = potentiometerValue;   // CCR1 PWM duty cycle set by potentiometer

 }
}


long map(long x, long in_min, long in_max, long out_min, long out_max)
{
 return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}

int analogRead(unsigned int pin) {
 ADC10CTL1 = ADC10SSEL_2 + pin;
 ADC10CTL0 |= ENC + ADC10SC;
 for(; {
   if ((ADC10CTL1 ^ ADC10BUSY) & ((ADC10CTL0 & ADC10IFG)==ADC10IFG)) {
     ADC10CTL0 &= ~(ADC10IFG +ENC);
     break;
   }
 }
 return ADC10MEM;
}

void initADC()
{
 ADC10CTL0 = ADC10ON + ADC10SHT_0 + SREF_0;
}

void stopWDT()
{
WDTCTL = WDTPW + WDTHOLD;
}

void initTimerA()
{
P1DIR |= motorPin;             // PWM out on P1.2
P1SEL |= motorPin;
CCR0 = 1000-1;             // Setting PWM period
CCTL1 = OUTMOD_7;          // CCR1 reset/set
TACTL = TASSEL_2 + MC_1;   // SMCLK configured for up mode

}

[jsolarski-backup 22]

I would improve it by having the ADC just transfer the data to the variable automatically. so when the Timer ISR happens you can run your map function and change the pwm with out any real cpu usage outside of the isr.

 

But otherwise I like your code, Simple and short and works

[jpnorair 340]

Why are you passing longs in a system where the hardware has 16 bit registers? That is, CCR1 is 16 bits.

[SirPatrick 35]

Oversight and neglecting to use standard definitions in stdint.h. I am new to this.