Arduino Uno code, Please explain what does this code do?
unsigned long ms_runtime;
int one_ms_timer;
//define all timers as unsigned variables
unsigned long timer1 = 0; // timer1 increments every 100ms =0.1s
const int USER_LED_OUTPUT = 13;
const int USER_BUTTON_INPUT = 2;
void setup()
{ // initialize the digital pin as an output.
pinMode(USER_LED_OUTPUT, OUTPUT);
pinMode(USER_BUTTON_INPUT, INPUT);
Serial.begin(9600);
}
void loop()
{ // run loop forever
static int state, old_state,counter;
timers();
// logic for state change
if(state == 0)
{ if(digitalRead(USER_BUTTON_INPUT) == 1)
{ if(timer1 > 5)
state = 1;
}
else
timer1 = 0;
}
else if(state == 1)
{ if(digitalRead(USER_BUTTON_INPUT) == 0)
{ if(timer1 > 5)
state = 0;
}
else
timer1 = 0;
}
// execute commands based on state
if (state == 1)
digitalWrite(USER_LED_OUTPUT, HIGH);
else if (state == 0)
digitalWrite(USER_LED_OUTPUT, LOW);
// monitor and print changed of state
if(old_state != state)
{ counter++;
Serial.print(\"counter = \");
Serial.println(counter);
old_state = state;
}
}
void timers(void)
{
int i;
if(millis() > (ms_runtime + 1))
{ ms_runtime = ms_runtime + 1;
one_ms_timer++;
}
else if( ms_runtime > millis())
ms_runtime = millis();
if(one_ms_timer > 99)
{ timer1++;
one_ms_timer = 0;
}
}
