controlling a 7 segment display with two buttons

Forum 2005-2010 (read only) Software Syntax & Programs
1

Hi there

I'm trying to control a 7 segment display with two buttons, one to reset it and another to start/stop it. I'm having trouble with my code and was wondering if anyone could point out where i'm going wrong with it?

#include <LedControl.h>

LedControl lc=LedControl(12,11,10,1); //* Pin 12 is connected to the DATA IN-pin of the first MAX7221 pin 1
//* Pin 11 is connected to the CLK-pin of the first MAX7221 PIN 13
//* Pin 10 is connected to the LOAD(/CS)-pin of the first MAX7221 PIN 12

int w,x,y,z;
int button = 2;
int BUTTON = 3;
int buttonvalue=0;
int BUTTONVALUE=0;
int buttonPin=0;
int state=0;
int p=0;
void setup(){

pinMode(button, INPUT);
pinMode(BUTTON, INPUT);
lc.shutdown(0,false);
lc.setIntensity(0,8);
lc.clearDisplay(0);
Serial.begin(9600);
}

void loop(){

// handle button presses

int BUTTON = digitalRead(BUTTON);
if(BUTTON==LOW){
Serial.println(" BUTTON LOW");

if (state==0){
state=0;
}

int but = digitalRead(button);
if(but==LOW){
Serial.println("button LOW");

if(state==0){
state=1;
}
else if(state==1){
state=2;
}
else if(state==2){
state=1;
}
}

// now act according to state

Serial.println(state);

if(state==0){

lc.setDigit(0,0,0,false); //first driver, digit 0, w is minutes
lc.setDigit(0,1,0,true);
lc.setDigit(0,2,0,true);
lc.setDigit(0,3,0,false);
}

if(state==1){

unsigned long t=millis();

int mins = (t / (1000UL * 60)) % 60; // calculate minutes
int secs = (t / 1000) % 60; // seconds
int hths = t % 100; // hundredths of seconds

w = mins / 10; //
x = mins % 10;
y = secs / 10;
z = secs % 10; // % sign means modulo which does the divison and gives remainder

lc.setDigit(0,0,w,false); //first driver, digit 0, w is minutes
lc.setDigit(0,1,x,true);
lc.setDigit(0,2,y,true);
lc.setDigit(0,3,z,false);
}

if (state==2){
// do nothing
}
// ------- debounce code ---------

delay(100);
}

// a function-based version of http://www.arduino.cc/en/Tutorial/Debounce
// by Dave Mellis.

int buttonState; // the current reading from the input pin
int lastButtonState = LOW; // the previous reading from the input pin
// the following variables are long's because the time, measured in miliseconds,
// will quickly become a bigger number than can be stored in an int.
long lastDebounceTime = 0; // the last time the output pin was toggled
long debounceDelay = 50; // the debounce time; increase if the output flickers

// debounceRead() -- debounced version of digitalRead()

int debouncedRead(int p); {
// read the state of the switch into a local variable:
int reading = digitalRead(p);
// check to see if you just pressed the button
// (i.e. the input went from LOW to HIGH), and you've waited
// long enough since the last press to ignore any noise:
// If the switch changed, due to noise or pressing:
if (reading != lastButtonState) {
// reset the debouncing timer
lastDebounceTime = millis();
}
if ((millis() - lastDebounceTime) > debounceDelay) {
// whatever the reading is at, it's been there for longer
// than the debounce delay, so take it as the actual current state:
buttonState = reading;
}

// save the reading. Next time through the loop,
// it'll be the lastButtonState:
lastButtonState = reading;
return buttonState;
}

2

You could do yourself a favour and decide what is a button state and what is a button pin, and name your variables unambiguously accordingly.

This line:

int BUTTON = digitalRead(BUTTON);

merits some attention.

BTW Saying "I'm having trouble" doesn't mean very much to anyone else if we don't know what the expected behaviour and the observed behaviour are.

3

the button state is telling the button which state to run so if button is state 1 and then is pressed run state 2, button pin is the pin going into the arduino

4

Did you mean "button", or "BUTTON" (either one) ? :wink:

Seriously, look at the scope rules for 'C' and then look at the line I highlighted.

5

sorry, I'm a bit of a beginner with arduino so i'm not sure what you mean. as far as "button" and "BUTTON" go i thought i had to give them two different names when i declare them at the start of the project.

6

OK, yes calling them different names is a good idea BUT:

int BUTTON = digitalRead(BUTTON);

Creates an "int" called "BUTTON" and then calls "digitalRead" with the value of the newly-created "int" as its parameter.
But BUTTON hasn't got a valid value, because you haven't initialised it yet.

7

thanks that seems to have helped only problem i'm having now is with this part of the code

In function 'void loop()':
error: return-statement with a value, in function returning 'void

}

// save the reading. Next time through the loop,
// it'll be the lastButtonState:
lastButtonState = reading;
return buttonState;
}

do you have any suggestions as i'm stuck with this as well

thank you for your help so far

8

This int debouncedRead(int p); { will (and have) cause you pain.
Try int debouncedRead(int p) {

:slight_smile:

9

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