Question

. It is desired to write an interrupt driven software for the robot. Two global variables namely, currentStatus and previous Status should be declared that represent the current and previous state of the robot, Initially, both should be set to STOPPED. The robot can have several states (for example, STOPPED, MOVING, COLLECTING, etc.). Write the following C function to initialize all /O ports (5 points) C function to initial the ADC (5 points) a. b. C. d. e. f. C function to read from any ADC channel (5 points) C function to initialize timer interrupt every 10ms (5 points). C function to setup PWM to control two motors (5 points) Interrupt Service Routine (ISR) for the above (part c) timer interrupt. The ISR should monitor the various sensors and change the values of the global varíables to facilitate the main C function to navigate the robot, collect objects, avoid collision, etc. (15)

Answer 1

//**********************Include Library FILES*******************************//
#include<p18f67k22.h>
#include<stdio.h>

//**********************Variable Declaration*******************************//

unsigned int currentStatus=0,previousStatus=0; //initially define as Stopped
unsigned long decimalNum=0;
unsigned int isr_us=10000; //ISR for 10ms
unsigned int crystal_freq_MHZ=20;
unsigned int presclar_value=1;

unsigned long IsrDecimalValue=0,quotient;
unsigned int remainder;
unsigned int low_v,high_v,speed;

//*********************************** function definition*****************************************//
void timer1_init(void)
{
   INTCONbits.GIEH = 1; //Set Global Interrupt Enable
   INTCONbits.GIEL = 1; //Set Global Interrupt Enable      
   T1CONbits.RD16=0;  
   T1CONbits.NOT_T1SYNC=0;  
   T1CONbits.SOSCEN=0;  
   T1CONbits.T1CKPS0=0;
   T1CONbits.T1CKPS1=0;
   T1CONbits.TMR1CS0=0;
   T1CONbits.TMR1CS1=0;
   PIE1bits.TMR1IE=1; //TIMER1 OVERFLOW INTERRUPT ENABLE
   PIR1bits.TMR1IF=0; //TIMER1 OVERFLOW INTERRUPT FLAG BIT
   isr_calulation();
   TMR1L=low_v;          
   TMR1H=high_v;
   T1CONbits.TMR1ON=1;
}
void PWM_init()
{
   TRISAbits.TRISA2=1;
   PWM3CON=0;
   PR2=255;
   PWM3DCH=0x00;
   PWM3DCL=0x00;
   PIR1bits.TMR2IF=0;
   T2CON=0x03;
   PWM3DCL=0;
   T2CONbits.TMR2ON=1;
   PWM3CONbits.PWM3EN=1;
   TRISAbits.TRISA2=0;
   PWM3CONbits.PWM3OE=1;
   PWM3CON=0xF0;
}
void ADC_Init(unsigned char chanel)//to convert digital channel to analog
{
   num=chanel;
   ADCON0=(num1|(num<<2));//num1=0000 0001 or num=channel
   ADCON1 = 0xF0;//1 = Right justified;111 = FRC (clock supplied from a dedicated RC oscillator);Unimplemented: Read as ‘0’;00 = VREF+ is connected to VDD
}

void Readadc(void)//read adc channel
{
   ADCON0bits.GO=1; //1 = A/D conversion cycle in progress
   while(ADCON0bits.GO==1); // Wait for completion
   //ConvertADC(); // Start conversion
   //while(BusyADC()); // Wait for completion
   a = ADRESH; //ADC RESULT REGISTER HIGH bits;Upper 2 bits of 10-bit conversion result
   b = ADRESL; //ADC RESULT REGISTER low bits;Lower 8 bits of 10-bit conversion result

//****combine high and low adc value of 10 bit********//
   thld = a;
   thld = thld<<8;
   thld = thld | b;                       
}
void isr_calulation() //isr for 10 ms   
{  
   decimalNum = isr_us * ((crystal_freq_MHZ/4)*(1/presclar_value));                         
   IsrDecimalValue = 65535 - decimalNum;
   low_v = IsrDecimalValue & 0xff;
   IsrDecimalValue = IsrDecimalValue/256;
   high_v = IsrDecimalValue & 0xff;
}
/*********************ISR*********************/

#pragma code high_vector=0x08
#pragma interrupt high_isr
void interrupt_at_high_vector(void)
{
   _asm GOTO high_isr _endasm
}
#pragma code /* return to the default code section */

void high_isr(void)
{
   if (PIR1bits.TMR1IF == 1) //Check Timer 1 Overflow Interrupt Flag To make sure this is a Timer 1 interrupt.
   {   //Peripheral Interrupt Request Flag registers
       PIR1bits.TMR1IF=0;
       TMR1L=low_v;          
       TMR1H=high_v;
       --count;
      
       Read_Sensor(); //read Sensor data and update
      
   }
}
//*******main initialization*****//////
void main()
{
   //CLEAR ALL PORT
   PORTA=0x00;
   PORTB=0x00;
   PORTC=0x00;
   PORTD=0x00;

   //CONTROLLER REGISTER SET AND RESET ACORDING TO NEED
   CM1CON=0x00;//comparator disable
   CM2CON=0x00;
   CM3CON=0x00;

   //CLEAR ALL LAT
   LATA=0X00;
   LATB=0X00;
   LATC=0X00;
   LATD=0X00;

   //DEFINE ANALOG TO DIGITAL
   ADCON0=0x01; //channel 0 define as analog
   ADCON1=0x00;
   ADCON2=0x00;
   ANCON0=0X01;
   ANCON1=0X00;
   ANCON2=0X00;

   //DEFINE DIRECTION AS INPUT AND OUTPUT
   TRISA=0xFF; //define as input
   TRISB=0xFF;
   TRISC=0X00; //define as output
   TRISD=0X00;

   //FUNCTION INITIALIZATION
   timer1_init();//timer initilization
  
   PWM_init(); //PWM Init
  
   while(1)
   {
       ADC_Init(0); //init channel 0
       Readadc(); //read channel 0s
      
       PWM3DCH=speed; //motor control according to speed,Pwm pin connected to motor1 and motor2
  
   }  
}