Day 12: Data Files | LCD Displays

Lab

LCD Displays

LCD displays can display values on the screen, and also allow someone to interact with it by pressing buttons on it.
1023
Select: 740-741
Left: 503
Down: 326-327
Up: 142-143
Right: 0

Lecture

Data Files

I/O Statements

Must use pointers to reference
file pointer defined with FILE declaration as in FILE *sensor1;
Asterisk before identifier specifies that identifier is a pointer

sensor=fopen("sensor1.txt","r");

fopen function optains info needed to assign file pointer for specific file.
R is for read, w is for write

Homework

Hardware

//LCD with Progress Bar

//Include the library code:

#include <LiquidCrystal.h>

//Initialize the library with the numbers of the interface pins

LiquidCrystal lcd(8,9,4,5,6,7);

//Create the progress bar characters

byte p20[8] = {

B10000,

};

byte p40[8] = {

B11000,

};

byte p60[8] = {

B11100,

};

byte p80[8] = {

B11110,

};

byte p100[8] = {

B11111,

};

void setup()

{

pinMode(11,OUTPUT);

//Set up the LCDs number of columns and rows:

lcd.begin(16, 2);

// Print a message to the LCD.

lcd.print("ENGR6 Display");

//Make progress characters

lcd.createChar(0, p20);

lcd.createChar(1, p40);

lcd.createChar(2, p60);

lcd.createChar(3, p80);

lcd.createChar(4, p100);

}

void loop()

{

//Move cursor to second line

digitalWrite(11,HIGH);

lcd.setCursor(0,1);

//Clear the line each time it reaches the end

//with 16 " " (spaces)

//lcd.print(" ");

//Iterate through each character on the second line

for (int i = 0; i<16; i++)

{

//Iterate through each progress value for each character

for (int j=0; j<5; j++)

{

lcd.setCursor(i, 1); //Move the cursor to this location

lcd.write(j); //Update progress bar

delay(100); //Wait

}

Software

The homework asked us to print the velocity and altitude of a weather balloon given a starting time, ending time, and increment. We also needed to modify it to find the maximum, check that the user's inputs made sense, and to write it to a text file.

Code:
//Weather Balloon
/*This program prints the altitude and velocity for a weather balloon
with a given start time, increment in time, and ending time*/

#include <stdio.h>
#include <math.h>
#define FILENAME "balloon.txt"

int main(void){
float startTime, incTime, endTime, alt, vel, t;
FILE *balloon;
balloon=fopen(FILENAME,"w"); //Open output file

//Take user inputs
printf("Input start time in hours: ");
scanf("%f",&startTime);
printf("\n Input end time in hours: ");
scanf("%f",&endTime);
printf("\n Input time increment in minutes: ");
scanf("%f",&incTime);
incTime=incTime/60; //Convert minutes into hours

float maxAlt=0, maxAltTime, velMS, totalVel;
float totalMaxTime, totalMaxAlt=0, totalAlt;

int j=0;

if(j==0)
{
while(endTime<=startTime) //Make sure that the starting time is less than the ending time
{
printf("\n End time must be greater than start time\n");
printf("Please re-input times\n");
printf("Input start time in hours: ");
scanf("%f",&startTime);
printf("\nInput end time in hours: ");
scanf("%f",&endTime);
}

while(startTime>=48 || startTime<0)//Make sure start time falls in proper range
{
printf("\n Start time must be between 0 and 48 hours. Re-enter start time\n");
printf("Input start time in hours: ");
scanf("%f",&startTime);
t=startTime;
}

while(endTime>=48 || endTime<0)//Make sure end time falls in proper range
{
printf("\n End time must be between 0 and 48 hours. Re-enter end time\n");
printf("Input end time in hours: ");
scanf("%f",&endTime);
}

while(incTime>=48 || incTime<0)//Make sure time increment falls in proper range
{
printf("\nTime increment must be between 0 and 48 hours. Re-enter time increment\n");
printf("Input time increment in minutes: ");
scanf("%f",&incTime);
}

if(startTime<endTime)
{
t=startTime;
printf("Time Altitude Velocity\n");
while(t<=endTime)
{
alt=-0.12*pow(t,4) + 12*pow(t,3) - 380*t*t + 4100*t + 220; //Calculate altitude
vel=-0.48*pow(t,3) + 36*t*t - 760*t + 4100; //Calculate velocity
velMS=vel/3600; //Covert meters per hour to meters per second

printf("%.4f %.4f %.4f \n",t,alt,velMS); //Print values in console
fprintf(balloon,"%7.4f %7.4f %7.4f \n",t, alt, velMS); //Print values to file
if(alt>maxAlt)
{
maxAlt=alt; //Find maximum altitude and time that balloon reaches altitude
maxAltTime=t;
}
t+=incTime; //increment time

if(t>=endTime)
{
j=1; //Break from loop
}
}

for(int i=0; i<=191; i++) //Find max altitude for all 48 hours
{
int k=i*0.25;
totalAlt=-0.12*pow(k,4) + 12*pow(k,3) - 380*k*k + 4100*k + 220;
if(totalAlt>totalMaxAlt)
{
totalMaxAlt=totalAlt;
totalMaxTime=k;
}
}
}
}
//Print max altitude for range
printf("The maximum altitude for the specified range is %.4f meters, and is reached at time %.4f hours after balloon launch\n",maxAlt,maxAltTime);
//Print max altitude for entire flight
printf("\nThe maximum altitude during the entire flight is %.4f meters, and is reached at time %.4f hours after balloon launch\n",totalMaxAlt,totalMaxTime);
//Close file
fclose(balloon);
return 0;

}

Day 20: Structures, Programming with Pointers

Lecture Structures Structure defines set of data, but individual parts do not have to be the same type. Example 1.1 struct hurricane { char name[10]; int year,category; }; Within a structure, variables and even arrays can be defined. Structures are also known as aggregate data types since multiple data values can be collected into a single data type. Individual values within a structure are called data members, and each member is given a name. In Example 1.1, the names of the data members are name, year, and category. To refer to a data member, the structure variable name followed by a period and a data member name is used. Definition and Initialization Define structure. Keyword struct used to define name of structure (aka structure tag) and data members that are included in structure After structure defined, structure variables can be defined using declaration statements. Semicolon required after structure definition. Statements can appear before m...

Engineering 6 CBraga

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