Ultrasonic Sensor Code
Note: This code works with up to 2 ultrasonic sensors in either port 1 or 2. which can be configured by commenting out or removing comments. Thank you Kevin for the inspiration.
#ifndef __ULTRASONIC_HEADER__
#define __ULTRASONIC_HEADER__
//Choose which digital pin will be the output
//you may only need one pin for this unless the sensors
//are in conflicting direction. Make sure it is
//set as an OUTPUT in user_routines.c In this
//example I am going to use two so I can control
//each indevidually
#define ULTRASONIC_OUTPUT_PORT1 rc_dig_out15;
#define ULTRASONIC_OUTPUT_PORT2 rc_dig_out14;
//We only need one input port if we have 2 output ports so
//that frees up one interrupt port, and 1 & 2 are
//the best/easiest to use. Comment out the one you dont
//want to use
#define ULTRASONIC_INTERRUPT_PORT1 rc_dig_in01;
//#define ULTRASONIC_INTERRUPT_PORT2 rc_dig_in02;
//Do not change these are used for the arguments
//in the functions for which sensor you want
#define ULTRASONIC_SENSOR1 1;
#define ULTRASONIC_SENSOR2 2;
//Variable used for the interrupt routine to
//Tell which sensor is being used
extern unsigned char UltrasonicNumber;
//Copy of the time for each of the 2 sensors
extern volatile unsigned int Ultrasonic_1_Time;
extern volatile unsigned int Ultrasonic_2_Time;
//Call in User_Initilization in User_Routines.c
void Initilize_Ultrasonic(void);
//Use to test your sensor
unsigned int Ping_Test(unsigned char Sensor_Number);
//Use this before you get the distance
void Ping(unsigned char Sensor_Number);
//Get the current distance on a certain sensor
unsigned int Get_Distance(unsigned char Sensor_Number);
//Disable Ultrasonic sensor on a certain port
void Disable_Ultrasonic(unsigned char Sensor_Number);
//Enable Ultrasonic sensor on a certain port;
void Enable_Ultrasonic(unsigned char Sensor_Number);
//Interrupt routine. replace "INTCON3bits.INT2IF = 0;"
//in user_routines_fast.c with "Ultrasonic_Interrupt_Routine()"
//if you are using interrupt port 1
//or "INTCON3bits.INT3IF = 0;" for port 2
void Ultrasonic_Interrupt_Routine(void);
#endif
#ifndef ULTRASONIC_INTERRUPT_PORT1
#ifndef ULTRASONIC_INTERRUPT_PORT2
#error You must select one interrupt port to use!
#endif
#endif
/*
Program for Parallax PING))) ultrasonic sensor
www.parallax.com
Author: William Toth
Date: 01/22/08
Description: Sets up all things needed to measure the pulses
created by the sensor. This can use 2 sensors. Each sensor gets
wired to 1 interrupt port (either 1 or 2) and one regular port that
you define below
*/
#include "ifi_default.h"
#include "Ultrasonic.h"
#include "ifi_aliases.h"
//Variable used for the interrupt routine to
//Tell which sensor is being used
unsigned char UltrasonicNumber;
//Copy of the time for each of the 2 sensors
volatile unsigned int Ultrasonic_1_Time;
volatile unsigned int Ultrasonic_2_Time;
//Call in User_Initilization in User_Routines.c
void Initilize_Ultrasonic(void)
{
//Set what you want for this timer. In my case
//I am using a prescaler of 8.
T3CON = 0b00110000;
//check to see which port you chose
#ifdef ULTRASONIC_INTERRUPT_PORT1
// make sure interrupt 1 is configured as an input
//it is in the default code "digital_io_01" is the
//same as "TRISBbits.TRISB2"
TRISBbits.TRISB2 = 1;
// interrupt 1 is low priority
INTCON3bits.INT2IP = 0;
// trigger on rising edge
INTCON2bits.INTEDG2 = 1;
// make sure the interrupt flag is reset before enabling
INTCON3bits.INT2IF = 0;
//keep disabled it for now
INTCON3bits.INT2IE = 0;
#endif
#ifdef ULTRASONIC_INTERRUPT_PORT2
// make sure interrupt 2 is configured as an input
//it is in the default code
TRISBbits.TRISB3 = 1;
// interrupt 2 is low priority
/*Note: If you get an error on this line saying
"Unknownn tag _INT3IP_ or something like that
go into the file p18f8722.h in C:\mcc18\h and change the
line that says "INT3P" to "INT3IP" */
INTCON2bits.INT3IP = 0;
// trigger on rising edge
INTCON2bits.INTEDG3 = 1;
// make sure the interrupt flag is reset before enabling
INTCON3bits.INT3IF = 0;
//keep disabled it for now
INTCON3bits.INT3IE = 0;
#endif
}
//Use to test your sensor
unsigned int Ping_Test(unsigned char Sensor_Number);
void Ping(unsigned char Sensor_Number)
{
unsigned short x; //for counter
//Set it to get input on rising edge
INTCON2bits.INTEDG2 = 1;
//Set which sensor we are using
UltrasonicNumber = Sensor_Number;
#ifdef ULTRASONIC_INTERRUPT_PORT1
//Enable the interrupt on port 1
INTCON3bits.INT2IE = 1;
#endif
#ifdef ULTRASONIC_INTERRUPT_PORT2
//Enable the interrupt
INTCON3bits.INT3IE = 1;
#endif
//Turn the timer on
T3CONbits.TMR3ON = 1;
//Set it to output to start the pulse
if(Sensor_Number==1)
{
//ULTRASONIC_OUTPUT_PORT1 = 1;
rc_dig_out15 = 1;
}
else if(Sensor_Number==2)
{
//ULTRASONIC_OUTPUT_PORT2 = 1;
rc_dig_out14 = 1;
}
//wait for 2-5 us (approx)
for(;x<=10;x++);
//stop the pulse
if(Sensor_Number==1)
{
//ULTRASONIC_OUTPUT_PORT1=0;
rc_dig_out15 = 0;
}
else if(Sensor_Number==2)
{
//ULTRASONIC_OUTPUT_PORT2=0;
rc_dig_out14 = 0;
}
}
//Get the current distance on a certain sensor
unsigned int Get_Distance(unsigned char Sensor_Number)
{
//So that everytime the code runs this function we get the same value we
//wont edit the timer value
unsigned int ReturnValue;
//Disable Interrupts while accessing the values.
#ifdef ULTRASONIC_INTERRUPT_PORT1
//disable the interrupt on port 1
INTCON3bits.INT2IE = 0;
#endif
#ifdef ULTRASONIC_INTERRUPT_PORT2
//disable the interrupt
INTCON3bits.INT3IE = 0;
#endif
//The speed of sound is 340.29 m/s or
//13,560 feet/second, but the metric sytem is much much
//easier to work with So that is 340,290 mm/s
//1 second = 1,000,000 us (microseconds)
//so .34029 mm/us
//For the timer the equation is as follows:
// (prescale factor)*(Timer value)=time elapsed in us
// prescale we use is 8
if(Sensor_Number == 1)
{
//Devide by 2 because the reading we get is timer there and time back
ReturnValue = Ultrasonic_1_Time / 2;
/*****Enable the interrupt again****/
#ifdef ULTRASONIC_INTERRUPT_PORT1
//Enable the interrupt on port 1
INTCON3bits.INT2IE = 1;
#endif
#ifdef ULTRASONIC_INTERRUPT_PORT2
//Enable the interrupt
INTCON3bits.INT3IE = 1;
#endif
//Now plugin our equation ReturnValue = TimerValue
ReturnValue *= 8;
// the *11 and >> 6 is the same as ReturnValue * .34029
//except that it is faster then using a float
//return (ReturnValue*11)>>6; //This is in milimeters
return ReturnValue * .34029;
}
else if(Sensor_Number == 2)
{
//Devide by 2 because the reading we get is timer there and time back
ReturnValue = Ultrasonic_2_Time / 2;
/*****Enable the interrupt again****/
#ifdef ULTRASONIC_INTERRUPT_PORT1
//Enable the interrupt on port 1
INTCON3bits.INT2IE = 1;
#endif
#ifdef ULTRASONIC_INTERRUPT_PORT2
//Enable the interrupt
INTCON3bits.INT3IE = 1;
#endif
//Now plugin our equation ReturnValue = TimerValue
ReturnValue *= 8;
// the *11 and >> 6 is the same as ReturnValue * .34029
return ((ReturnValue*11)>>6); //This is in milimeters
}
}
//Disable Ultrasonic sensor on a certain port
void Disable_Ultrasonic(unsigned char Sensor_Number);
//Enable Ultrasonic sensor on a certain port
//only use after a Disable function has been called
void Enable_Ultrasonic(unsigned char Sensor_Number);
//Interrupt routine. replace "INTCON3bits.INT2IF = 0;"
//in user_routines_fast.c with "Ultrasonic_Interrupt_Routine()"
//if you are using interrupt port 1
//or "INTCON3bits.INT3IF = 0;" for port 2
void Ultrasonic_Interrupt_Routine(void)
{
//If the interrupt for rising edge hasnt happened
if(INTCON2bits.INTEDG2)
{
//reset the timer;
TMR3H = 0x00;
TMR3L = 0x00;
#ifdef ULTRASONIC_INTERRUPT_PORT1
// trigger the next one on falling edge
INTCON2bits.INTEDG2 = 0;
#endif
#ifdef ULTRASONIC_INTERRUPT_PORT2
// trigger the next one on falling edge
INTCON2bits.INTEDG3 = 0;
#endif
}
else
{
//turn off the timer
T3CONbits.TMR3ON = 0;
#ifdef ULTRASONIC_INTERRUPT_PORT1
// trigger the next one on rising edge
INTCON2bits.INTEDG2 = 1;
#endif
#ifdef ULTRASONIC_INTERRUPT_PORT2
// trigger the next one on rising edge
INTCON2bits.INTEDG3 = 1;
#endif
/*
//Store the time
Ultrasonic_1_Time = (unsigned int)TMR3H<<8;
Ultrasonic_1_Time |= (unsigned int)TMR3L;
*/
if(UltrasonicNumber==1)
{
//Store the time
Ultrasonic_1_Time = (unsigned int)TMR3H<<8;
Ultrasonic_1_Time |= TMR3L;
//UltrasonicNumber |= 0x80;
}
else if(UltrasonicNumber==2)
{
//Store the time
Ultrasonic_2_Time = (unsigned int)TMR3H<<8;
Ultrasonic_2_Time |= TMR3L;
//UltrasonicNumber &= 0x7F;
}
}
}
Click Here for the non-functioning code meant for ports 3-6. I could not figure out why I couldn't get it to work.
Program for Parallax PING))) ultrasonic sensor
www.parallax.com
Author: William Toth
Date: 01/22/08
Description: Sets up all things needed to measure the pulses
created by the sensor. This can use up to 2 sensors
*/