Toggle pin on Arduino Micro without disrupting operation - arduino

Question

I have a code that once it receives a particular input over the serial it will turn 2 pins high, and wait for an interrupt to occur and run its code. I tried using an infinite loop(while 1) but the interrupt routine can't get executed when the button is pressed.
I want the outputs LED and BEEP to toggle after 'C' is received and until the interrupt occurs.
// Declarations before
void loop() {
while(Serial.available())
{
char data = Serial.read();
if(data == 'C')
{
digitalWrite(BEEP, 1);
digitalWrite(LED, 1);
flag = true;
}
}
// Interrupt routine

Answer 1

When this code receives a 'C' char from the serial the code starts a led flashing for 50 msec on and for 50 msec off, the led flashing stops when the interrupt ITR_PIN is generated (the ISR buttonPressed function will be called!)
#define ITR_PIN 3
volatile bool start = false;
bool ledstatus = false;
int LED= 4;
/**
* This method is called on the interruption raised on the falling front of the PIN2
* The start flag is used to avoid rebound front. Interruptions are disabled inside the
* interrupt vector method.
* start is reset once it has been processed in the main loop()
*/
void buttonPressed()
{
start=false;
}
void setup()
{
cli();
pinMode(ITR_PIN, INPUT);
pinMode(LED, OUTPUT);
attachInterrupt(0, buttonPressed, FALLING); // Pin 3
sei();
Serial.begin(9600);
}
void loop(){
while(Serial.available())
{
char data = Serial.read();
if(data == 'C')
{
start = true;
}
}
if (start)
{
ledstatus=!ledstatus;
digitalWrite(LED, (ledstatus)?HIGH:LOW);
delay(50);
} else {
if (ledstatus) {
ledstatus=false;
digitalWrite(LED,LOW);
}
}
}

Answer 2

I just tried this on a simulator:
#define ITR_PIN 3
volatile boolean start = false;
volatile boolean flag = false;
int LED= 4;
/**
* This method is called on the interruption raised on the falling front of the PIN2
* The start flag is used to avoid rebound front. Interruptions are disabled inside the
* interrupt vector method.
* start is reset once it has been processed in the main loop()
*/
void buttonPressed()
{
if(flag)
{
if (!start)
{
start = true;
}
}
}
void setup()
{
cli();
pinMode(ITR_PIN, INPUT);
pinMode(LED, OUTPUT);
attachInterrupt(0, buttonPressed, FALLING); // Pin 3
sei();
Serial.begin(9600);
}
void loop(){
while(Serial.available())
{
char data = Serial.read();
if(data == 'C')
{
digitalWrite(LED, 1);
flag = true;
}
}
if(flag == true)
if (start)
{
digitalWrite(LED, LOW);
delay(50);
start = false;
flag=false;
}
}
(it's just a reduced version of yours, I just removed the stepper dependancies and marked flag as volatile). It works with this hardware:
However, I'm pretty sure that you haven't added the pullup to your circuit!
The solution is:
add a resistor (e.g. 10 kOhm) between pin 3 and +5V
enable the internal pullup
Solution 2 is the preferred one: you just have to change
pinMode(ITR_PIN, INPUT);
into
pinMode(ITR_PIN, INPUT_PULLUP);
EDIT:
According to your comment I think that the behavior should be different:
Everything is off
When you receive a C on the serial interface the led starts "blinking"
When the interrupt is asserted it stops blinking.
I modified the code to achieve this; I slightly reduced the rest of the code (but you can merge it with the previous one)
#define ITR_PIN 3
volatile boolean flag = false;
const int blink_period_ms = 500; // Blink period in milliseconds
unsigned long initialBlinkTime;
int LED= 4;
void buttonPressed()
{
flag = false;
}
void setup()
{
cli();
pinMode(ITR_PIN, INPUT);
pinMode(LED, OUTPUT);
attachInterrupt(0, buttonPressed, FALLING); // Pin 3
sei();
Serial.begin(9600);
}
void loop(){
while(Serial.available())
{
char data = Serial.read();
if(data == 'C')
{
if (!flag)
{
initialBlinkTime = millis();
flag = true;
}
}
}
if(flag)
{
int currentTime = millis() - initialBlinkTime;
while (currentTime > blink_period_ms) currentTime -= blink_period_ms;
digitalWrite(LED, currentTime < blink_period_ms/2);
// Insert here the other instructions
delay(50);
}
}