A program that I have written for the SMS ROBOT –
/* Header files */
#include<avr/io.h>
#include<avr/delay.h>
#include”at8ports.h”
int s[10]; /*GLOBAL VARIABLE to store INPUT in an array format*/
int sms; /*GLOBAL VARIABLE to receive incoming sms*/
/* Initialise input & output pins */
/*
PD0 is the sensor input pin
PB1 and PB2 are the motor speed control pins
PC0 to PC3 are the motor direction control pins
*/
void init_settings()
{
DDRD_IN(0); /* PD0 = Input */
DDRB_OUT(1); /* PB1 = Output */
DDRB_OUT(2); /* PB2 = Output */
DDRC_OUT(0); /* PC0 = Output */
DDRC_OUT(1); /* PC1 = Output */
DDRC_OUT(2); /* PC2 = Output */
DDRC_OUT(3); /* PC3 = Output */
}
/* Functions for different directions */
/* Direction is determined from PC0 to PC3 */
/*PB_ON(x) implies to turn ON PULL UP resistor of PBx i.e. set the Output of PBx as LOGIC 1*/
/*PB_OFF(x) implies to turn OFF PULL UP resistor of PBx i.e. set the Output of PBx as LOGIC 0*/
/*same concept applies to all other pins*/
void forward()
{
/* PB1 and PB2 will always be high */
PB_ON(1);
PB_ON(2);
/* PC0 to PC3 = 1010 */
/*This is the ideal forward condition i.e. Logic 1:Logic 0:Logic 1:Logic 0*/
PC_ON(0);
PC_OFF(1);
PC_ON(2);
PC_OFF(3);
}
void left()
{
/* PB1 and PB2 will always be high */
PB_ON(1);
PB_ON(2);
/* PC0 to PC3 = 0110 */
/* Left motor backward (so opposite LOGIC to FORWARD), Right motor forward*/
PC_OFF(0);
PC_ON(1);
PC_ON(2);
PC_OFF(3);
}
void right()
{
/* PB1 and PB2 will always be high */
PB_ON(1);
PB_ON(2);
/* PC0 to PC3 = 1001 */
/* Left motor forward, Right motor backward (so opposite LOGIC to FORWARD)*/
PC_ON(0);
PC_OFF(1);
PC_OFF(2);
PC_ON(3);
}
void backward()
{
/* PB1 and PB2 will always be high */
PB_ON(1);
PB_ON(2);
/* PC0 to PC3 = 0101 */
/*Both motors in Backward direction, exactly opposite to Forward*/
PC_OFF(0);
PC_ON(1);
PC_OFF(2);
PC_ON(3);
}
/* To take input from the sensors [PD0 to PD4] */
void sensors()
{
sms = PD_IN(0);
}
/*SOMEHOW WE HAVE TO BREAK THE DIGITS RECEIVED BY SMS SO THAT EACH DIGIT GETS STORED AS AN ELEMENT OF ARRAY s[ ] AND WE CAN THEN MANIPULATE TO OUR WISH. THIS I AM NOT UNABLE TO DO SO. AS OF NOW LET’S ASSUME OUR INCOMING sms IS A 2-DIGIT NO. CONSISTING OG 1 & 0. THESE DIGITS ARE ASSUMED TO BE STORED IN ARRAY FORMAT IN s[ ] in exactly same order*/
void main()
{
init_settings(); /* To initialise all input and output pins */
while(1) /* Infinite loop */
{
sensors(); /* To take sensor values and store them */
if(s[0] == 0 && s[1] == 1)
{A
left(); /* Take a left turn */
}
else if(s[0] == 1 && s[1] == 0) /* Rightmost sensor */
{
right(); /* Take a right turn */
}
else if(s[0] == 0 && s[1] == 0) /* No sensor on the line */
{
PB_OFF(1); /*Motors stopped
PB_OFF(2);
}
else /* Zero error condition [Move forward] */
{
forward(); /* Go straight ahead */
}
} /* End of while loop */
} /* End of the program */