Answer Happy

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
void update_lcd(void);
void heartbeat(void);
void timers(void);
int is_door_closed(void);
int is_door_open(void);
int is_sensor_on(void);
void motor_drive_open(void);
void motor_drive_close(void);
void motor_stop(void);
//OUTPUTS
const int LED_pin = 13;
const int open_output_pin = 6;
const int close_output_pin = 7;
//INPUTS
const int open_signal_pin = 8;
const int closed_signal_pin = 9;
const int sensor_pin = 10;
const int ch_A_pin = 8;//match to your project for encoder
signals
const int ch_B_pin = 9;//match to your project for encoder
signals
int door_state = 0;
unsigned int motor_position = 0;
unsigned long int timer1;
unsigned long int timer2;
unsigned long int heartbeat_timer;
unsigned long int update_lcd_timer;
void setup()
{
// set up the LCD's number of columns and rows:
lcd.begin(16, 2);
// Print a message to the LCD.
lcd.print("hello, world!");
//INPUTS
pinMode(sensor_pin,INPUT);
pinMode(open_signal_pin,INPUT);
pinMode(closed_signal_pin,INPUT);
//OUTPUTS
pinMode(LED_pin,OUTPUT);
pinMode(open_output_pin,OUTPUT);
pinMode(open_output_pin,OUTPUT);
}
void loop()
{
door_control();
update_lcd();
heartbeat();
timers();
read_encoder();
}
void door_control(void)
{
if(door_state == 0)
{
motor_stop();
if(is_sensor_on() == 1)
door_state = 1;
}
else if(door_state == 1)
{
motor_drive_open();
if(is_door_open() == 1)
{
door_state = 2;
timer1 = 0;
}
}
else if(door_state == 2)
{
motor_stop();
if(is_sensor_on() == 1)
timer1 = 0;
if(timer1 >= 20) //50 * 0.100 = 5s
{
door_state = 3;
}
}
else if(door_state == 3)
{
//pending implementation..........
motor_drive_close();
}
/*


switch(door_state)
{
case 0:
motor_stop();
if(is_sensor_on() == 1)
door_state = 1;
break;

case 1:
motor_drive_open();
if(is_door_open() == 1)
{
door_state =
2;
timer1 = 0;
}
break;
case 2:
motor_stop();
if(is_sensor_on() == 1)
timer1 = 0;

if(timer1 >= 50) //50 * 0.100
= 5s
{
door_state =
3;
}
break;
case 3:
//pending implementation
break;
}




*/
}
void motor_drive_open(void)
{
digitalWrite(open_output_pin,HIGH);
digitalWrite(close_output_pin,LOW);
}
void motor_drive_close(void)
{
digitalWrite(open_output_pin,LOW);
digitalWrite(close_output_pin,HIGH);
}
void motor_stop(void)
{
digitalWrite(open_output_pin,LOW);
digitalWrite(close_output_pin,LOW);
}
void update_lcd(void)
{
if(update_lcd_timer >= 5)
{
update_lcd_timer = 0;
lcd.setCursor(0,1);
lcd.print("i=");
lcd.print(is_sensor_on());
//lcd.setCursor(0,1);
lcd.print(" s=");
lcd.print(door_state);
lcd.print(" enc=");
lcd.print(motor_position);
}
}
void heartbeat(void)
{
if(heartbeat_timer<10) //first 10 (10
times 100 ms = 1s)
digitalWrite(LED_pin,HIGH);
else
{
digitalWrite(LED_pin,LOW);
if(heartbeat_timer>=20) //(between 10 and 20 -
another 1 s)
heartbeat_timer = 0; //When does the
timer get cleared?
}
}
int is_sensor_on(void)
{
/*if(digitalRead(sensor_pin) == 1)
return 1;
else
return 0;
*/
return digitalRead(sensor_pin);
}
int is_door_open(void)
{
return (motor_position >= 20);
/*
if(motor_position >= 20)
return 1;
else
return 0;
*/
}
int is_door_closed(void)
{ //pending implementation
//return value based on input for lab 5
//return value based on encoder count for final
}
void timers(void)
{
static unsigned long ms_runtime = 0;
static int one_ms_timer = 0;
if(millis() > ms_runtime)
{
ms_runtime++;
one_ms_timer++;
}
if(one_ms_timer > 99)
{ // our choice for 99 gives us increments of 100
ms
timer1++;
timer2++;
heartbeat_timer++;
update_lcd_timer++;
one_ms_timer = 0;
}
}
void read_encoder(void)
{
static int encoder_case;
int encoder_case_temp = 0;
if(digitalRead(ch_A_pin))
encoder_case_temp+=1;
if(digitalRead(ch_B_pin))
encoder_case_temp+=2;

if(encoder_case != encoder_case_temp)
{
Serial.print("case = ");
Serial.print(encoder_case_temp);
Serial.print(" position = ");
Serial.println(motor_position);
}
switch(encoder_case)
{
case 0:
if(encoder_case_temp == 2)
motor_position--;
if(encoder_case_temp == 1)
motor_position++;
break;
case 1:
if(encoder_case_temp == 0)
motor_position--;
if(encoder_case_temp == 3)
motor_position++;
break;
case 3:
if(encoder_case_temp == 1)
motor_position--;
if(encoder_case_temp == 2)
motor_position++;
break;

case 2:
if(encoder_case_temp == 3)
motor_position--;
if(encoder_case_temp == 0)
motor_position++;
break;
}

if(encoder_case != encoder_case_temp)
{
Serial.print("case = ");
Serial.print(encoder_case_temp);
Serial.print(" position = ");
Serial.println(motor_position);
}

encoder_case = encoder_case_temp;
}
explain the code step by step