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Topic: Missing return type for method 'ISR' (Read 1 time) previous topic - next topic

electronicstudent

Hello everyone,i am very new to arduino.right now im using ARDUINO DUEMILANOVE with ATmega 328P.

im doing my project for school.the problem is i cannot simulate the code and i did not understand what the problem is.this is my code.

#include "WProgram.h"

//Global variables to be used
int x;
int y;
int lastx;
int lasty;
long timer;
int idle_timer;
int threshold;
int cross_count;
int in_tune;
int average_val;
int pitch_diff;

int upper_bound;
int lower_bound;
int avg_cross;
int avg_counter;
int avg_upper;
int avg_lower;
float a, b;

int timer_divide;
int divide_by;

int string_select;
int select_pin_val;

int analogPin = 0; // analog to digital pin for signal input

int led_high = 13; // this LED will show user if a string's pitch is too high
int led_ok = 12; // this LED will show user if a string's pitch is correct
int led_low = 11; // this LED will show user if a string's pitch is too low

// these pins will light up to show which string the Atmega is comparing values for
int led_e4 = 10;
int led_b3 = 9;
int led_g3 = 8;
int led_d3 = 7;
int led_a2 = 6;
int led_e2 = 5;

int button_pin = 3; // input pin for user using a button to switch strings
int servoPin = 2; // control pin for servo motor

void setup()
{
// Set up timer 1 to generate an interrupt every 1 microsecond
TCCR1A = 0x00;
TCCR1B = (_BV(WGM12) | _BV(CS12));
OCR1A = .071;
TIMSK1 = _BV(OCIE1A);

x = 0;
lastx = 0;
y = 0;
lasty = 0;

timer = 0;
cross_count = 0;
avg_cross = 0;
avg_counter = 0;
string_select = 0;

//Set the input and output pins
pinMode(button_pin, INPUT);
pinMode(servoPin, OUTPUT);
pinMode(led_high, OUTPUT);
pinMode(led_ok, OUTPUT);
pinMode(led_low, OUTPUT);
pinMode(led_e4, OUTPUT);
pinMode(led_b3, OUTPUT);
pinMode(led_g3, OUTPUT);
pinMode(led_d3, OUTPUT);
pinMode(led_a2, OUTPUT);
pinMode(led_e2, OUTPUT);

Serial.begin(9600); // Opens serial port, sets data rate to 9600 bps
}

// Nothing is done in the Arduino loop, since timing is off.
void loop()
{
}

// Timer function running every microsecond
ISR(TIMER1_COMPA_vect)
{
timer++;
idle_timer++;

// Read button press to determine which string is to be detected
if (timer % 100 == 0)
{
select_pin_val = digitalRead(button_pin);
if (select_pin_val == HIGH)
{
string_select = ((string_select + 1) % 6);
Serial.print("string: ");
Serial.println(string_select);
}
}


// Depending on which string is selected, the proper variables are set
switch (string_select)
{
case 0:
digitalWrite(led_e4, LOW); // sets the proper LED on, all else off
digitalWrite(led_b3, LOW);
digitalWrite(led_g3, LOW);
digitalWrite(led_d3, LOW);
digitalWrite(led_a2, LOW);
digitalWrite(led_e2, HIGH);
a = 0.045;
b = 0.9099;
threshold = 150;
upper_bound = 77;
lower_bound = 33;
avg_upper = 57;
in_tune = 55; // This is the "in tune" average of cross counts for the string.
avg_lower = 53;
timer_divide= 2000;
divide_by = 3;
break;
case 1:
digitalWrite(led_e4, LOW); // sets the proper LED on, all else off
digitalWrite(led_b3, LOW);
digitalWrite(led_g3, LOW);
digitalWrite(led_d3, LOW);
digitalWrite(led_a2, HIGH);
digitalWrite(led_e2, LOW);
a = 0.0592;
b = 0.8816;
threshold = 150;
upper_bound = 88;
lower_bound = 44;
avg_upper = 67;
in_tune = 65; // This is the "in tune" average of cross counts for the string.
avg_lower = 63;
timer_divide = 2000;
divide_by = 3;
break;
case 2:
digitalWrite(led_e4, LOW); // sets the proper LED on, all else off
digitalWrite(led_b3, LOW);
digitalWrite(led_g3, LOW);
digitalWrite(led_d3, HIGH);
digitalWrite(led_a2, LOW);
digitalWrite(led_e2, LOW);
a = 0.0797;
b = 0.8406;
threshold = 150;
upper_bound = 117;
lower_bound = 63;
avg_upper = 97;
in_tune = 95; // This is the "in tune" average of cross counts for the string.
avg_lower = 93;
timer_divide = 2000;
divide_by = 3;
break;
case 3:
digitalWrite(led_e4, LOW); // sets the proper LED on, all else off
digitalWrite(led_b3, LOW);
digitalWrite(led_g3, HIGH);
digitalWrite(led_d3, LOW);
digitalWrite(led_a2, LOW);
digitalWrite(led_e2, LOW);
a = 0.0730;
b = 0.8541;
threshold = 130;
upper_bound = 50;
lower_bound = 15;
avg_upper = 29;
in_tune = 27; // This is the "in tune" average of cross counts for the string.
avg_lower = 26;
timer_divide = 500;
divide_by = 4;
break;
case 4:
digitalWrite(led_e4, LOW); // sets the proper LED on, all else off
digitalWrite(led_b3, HIGH);
digitalWrite(led_g3, LOW);
digitalWrite(led_d3, LOW);
digitalWrite(led_a2, LOW);
digitalWrite(led_e2, LOW);
a = 0.1270;
b = 0.7459;
threshold = 140;
upper_bound = 50;
lower_bound = 15;
avg_upper = 35;
in_tune = 34; // This is the "in tune" average of cross counts for the string.
avg_lower = 33;
timer_divide = 500;
divide_by = 4;
break;
case 5:
digitalWrite(led_e4, HIGH); // sets the proper LED on, all else off
digitalWrite(led_b3, LOW);
digitalWrite(led_g3, LOW);
digitalWrite(led_d3, LOW);
digitalWrite(led_a2, LOW);
digitalWrite(led_e2, LOW);
a = 0.1648;
b = 0.6705;
threshold = 150;
upper_bound = 60;
lower_bound = 20;
avg_upper = 47;
in_tune = 45; // This is the "in tune" average of cross counts for the string.
avg_lower = 43;
timer_divide = 500;
divide_by = 4;
break;
}

check_crossings();

// After the string input has been idle for a while, we take the average of a number of cross counts that were in bound.
if (idle_timer == 10000)
{
Serial.println("AVG AVG LOOK HERE AVG AVG");
average_val = avg_cross / divide_by;
Serial.println(average_val);

// If else statements for tuner lights
if ((average_val < avg_lower) && (average_val > 0))
{
// Turn off all string display lights to conserve power
digitalWrite(led_e4, LOW);
digitalWrite(led_b3, LOW);
digitalWrite(led_g3, LOW);
digitalWrite(led_d3, LOW);
digitalWrite(led_a2, LOW);
digitalWrite(led_e2, LOW);

// Sets the proper tuning LED on, all else off
digitalWrite(led_high, LOW);
digitalWrite(led_ok, LOW);
digitalWrite(led_low, HIGH);

pitch_diff = in_tune - average_val;
Serial.print("Pitch Difference Low: ");
Serial.println(pitch_diff);

// If the tuning is off by a questionably high amount, count it as an error in reading and do not turn the peg.
// Otherwise tune the peg for a period of time. This time depends on how far off the read average is.
if (pitch_diff < 20)
for(long i = 0; i < pitch_diff * 36000; i++)
{
digitalWrite(servoPin, HIGH); // start the pulse
delayMicroseconds(15); // pulse width
digitalWrite(servoPin, LOW); // stop the pulse
}
}

// Don't turn the peg if the guitar is in tune.
else if ((average_val >= avg_lower && average_val <= avg_upper) || (average_val == 0))
{
// Sets the proper tuning LED on, all else off
digitalWrite(led_high, LOW);
digitalWrite(led_ok, HIGH);
digitalWrite(led_low, LOW);
}

else if (average_val > avg_upper)
{
// Turn off all string display lights to conserve power
digitalWrite(led_e4, LOW);
digitalWrite(led_b3, LOW);
digitalWrite(led_g3, LOW);
digitalWrite(led_d3, LOW);
digitalWrite(led_a2, LOW);
digitalWrite(led_e2, LOW);

// Sets the proper tuning LED on, all else off
digitalWrite(led_high, HIGH);
digitalWrite(led_ok, LOW);
digitalWrite(led_low, LOW);

pitch_diff = average_val - in_tune;
Serial.print("Pitch Difference High: ");
Serial.println(pitch_diff);

// If the tuning is off by a questionably high amount, count it as an error in reading and do not turn the peg.
// Otherwise tune the peg for a period of time. This time depends on how far off the read average is.
if (pitch_diff < 20)
for(long i = 0; i < pitch_diff * 270000; i++)
{
digitalWrite(servoPin, HIGH); // start the pulse
delayMicroseconds(2); // pulse width
digitalWrite(servoPin, LOW); // stop the pulse
}
}

// Reset all variables used for pitch detection
cross_count = 0;
avg_cross = 0;
avg_counter = 0;
}

// We take the average of cross counts after the first value in bound. We dismiss the first value since it is usually inaccurate
// for finding a good average.
if (timer % timer_divide == 0){
if (cross_count > lower_bound && cross_count < upper_bound) {
if (avg_counter >= 1 && avg_counter < (divide_by + 1)) {
avg_cross = avg_cross + cross_count;
Serial.print("Runnin Avg cross sum: ");
Serial.println(avg_cross);
}
avg_counter++;
}
Serial.print("cross_count: ");
Serial.println(cross_count);
cross_count = 0;
}
}

void check_crossings()
{
lastx = x;
lasty = y;
x = analogRead(analogPin); // Read the input pin
y = a * x + a * lastx + b * lasty; // Apply Butterworth filter to eliminate high frequencies

// If the string crosses it's set threshold, add it to the count. If there are no crossings, the idle timer will begin to run.
if (lasty > threshold and y < threshold)
{
cross_count++;
idle_timer = 0;
}
}

the simulator will tell "missing return type for method 'ISR' ".i cant seem to understand.the original project is done by using ARDUINO DEICIMILA with ATmega 168.

can anyone help me?any help is appreciated.

PaulS

You have a function, ISR(). Every function needs to have a return type. Yours does not.

If your function does not return a value, its return type should be void.


electronicstudent

ISR(TIMER1_COMPA_vect)

thanks for trying to help.what is the code above exactly tells?and can u give maybe a link where i can understand about timer and ISR function pls?

thanks again. :smiley-roll-sweat:

retrolefty


You have a function, ISR(). Every function needs to have a return type. Yours does not.

If your function does not return a value, its return type should be void.




Would a function used as a ISR function ever be anything but a void function? As the original code that was interrupted didn't call the function how could the returned value be of value, and might that screw up the stack upon return if it was other then a void that returned a value?

Lefty

PaulS

Quote
Would a function used as a ISR function ever be anything but a void function? As the original code that was interrupted didn't call the function how could the returned value be of value, and might that screw up the stack upon return if it was other then a void that returned a value?

Typically, there are well-defined signatures for callback functions, like ISR. A function that does not have that signature will make the compiler unhappy, and nobody likes an unhappy compiler.

The compiler is checking that the number of values popped off the stack on return is equal to the number of bytes pushed onto the stack prior to the return. That the morons (I mean developers) on the Arduino team decided that no compiler warnings are to be displayed makes it hard to see that this is done.

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