Hi I am trying to get a 2 digit 7 segment to work with 2 shift registers and a button.
I have used the following sketch as a starting point, it works with one register and one digit can anybody point me in the right direction to make a 2 digit display with 2 shift registers to increment 0 - 99 on a button press.
I have a 2 digit common cathoid 2 digit 7 segment display.
Any help would be great.
_7segexampl.ino (3.46 KB)
I have no clue why that guy only lights one bar at a time.... He can just shift out the byte from numbers and be done!
For two segments, just shift out the first, then the second and only then toggle latch 
Thanks for the reply.
do i need to create another number int set of (10 numbers.)?
For two segments, just shift out the first, then the second
Not sure how to shift out the second? do you mean.
something like this?
digitalWrite(latchPin, LOW); // Set latchPin LOW while clocking these 8 bits in to the register
shiftOut(dataPin, clockPin, LSBFIRST, data);
shiftOut(dataPin, clockPin, LSBFIRST, data);
digitalWrite(latchPin, HIGH);
original code
const int latchPin = 5; // Pin connected to Pin 12 of 74HC595 (Latch)
const int dataPin = 6; // Pin connected to Pin 14 of 74HC595 (Data)
const int clockPin = 7; // Pin connected to Pin 11 of 74HC595 (Clock)
int upPin = 12; // pushbutton attached to pin 12
int downPin = 13; // pushbutton attached to pin 13
int currUpState = 1; // initialise currUpState as HIGH
int currDownState = 1; // initialise currDownState as HIGH
int prevUpState = 0;
int prevDownState = 0;
int counter = 0; // initialise counter as zero
int numbers[10] = // Describe each digit in terms of display segments 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
{
B11111100,
B01100000,
B11011010,
B11110010,
B01100110,
B10110110,
B10111110,
B11100000,
B11111110,
B11100110,
};
void setup()
{
pinMode(latchPin, OUTPUT); // set SR pins to output
pinMode(clockPin, OUTPUT);
pinMode(dataPin, OUTPUT);
pinMode(upPin, INPUT); // sets pin 12 as pushbutton INPUT
pinMode(downPin, INPUT); // sets pin 13 as pushbutton INPUT
}
void loop()
{
currUpState = digitalRead(upPin);
if (prevUpState != currUpState) // has the state changed from
{ // HIGH to LOW or vice versa
prevUpState = currUpState;
if (currUpState == HIGH) // If the button was pressed
counter++;
if(counter > 8) counter = 0; // increment the counter by one
}
if(counter > 8)
counter--;
show(numbers[counter]); // display the current digit
currDownState = digitalRead(downPin);
if (prevDownState != currDownState) // has the state changed from
{ // HIGH to LOW or vice versa
prevDownState = currDownState;
if (currDownState == HIGH) // If the button was pressed
counter--; // decrement the counter by one
}
if(counter < 0)
counter++;
show(numbers[counter]); // display the current digit
}
void show( byte number)
{
// Use a loop and a bitwise AND to move over each bit that makes up
// the seven segment display (from left to right, A => G), and check
// to see if it should be on or not
for(int j = 0; j <= 7; j++)
{
byte toWrite = number & (B10000000 >> j);
if(!toWrite) {
continue;
} // If all bits are 0 then no point writing it to the shift register,so break out and
//move on to next segment.
shiftIt(toWrite); // Otherwise shift it into the register
}
}
void shiftIt (byte data)
{
digitalWrite(latchPin, LOW); // Set latchPin LOW while clocking these 8 bits in to the register
shiftOut(dataPin, clockPin, LSBFIRST, data);
digitalWrite(latchPin, HIGH); //set latchPin to high to lock and send data
// put delay here if you want to see the multiplexing in action!
// delay(10);
}
This page (and sub pages) might be interesting.
They use the TPIC6C596, which is the same (coding) as the 74HC595, but with higher voltage/current outputs.
Leo..
Not sure how to shift out the second? do you mean. something like this?
Yes but send out a different byte of data in the second shift out.
And
gregchill:
do i need to create another number int set of (10 numbers.)?
No, the second display needs to display the same 10 digits doesn't it? One the single digits and the other the dozens. Aka, the first "value % 10" and the second "value / 10"
dozens
Only if the OP want to display the number in duodecimal format!
Haha, you're right! I'll never trust Google again when in doubt about a word 
I just meant the multiples of ten
Thanks eveyone
Yes but send out a different byte of data in the second shift out.
Do i need to create a new void function in order to do this?
No, you need to edit it 
No, you just need to split your 0..99 number into tens and units as septillion described.
But again, I see no use is sending each bar seperate so the code is a bit weird...
Quick edit (so not perfect) to give you an idea of the weird code....
//did some edits to remove the stupid parts...
const byte latchPin = 5; // Pin connected to Pin 12 of 74HC595 (Latch)
const byte dataPin = 6; // Pin connected to Pin 14 of 74HC595 (Data)
const byte clockPin = 7; // Pin connected to Pin 11 of 74HC595 (Clock)
const byte upPin = 12; // pushbutton attached to pin 12
const byte downPin = 13; // pushbutton attached to pin 13
bool prevUpState = 0;
bool prevDownState = 0;
int counter = 0; // initialise counter as zero
//Min and max value of the counter
const byte maxCount = 99;
const byte minCount = 0;
byte numberOfDigits = 2;
const byte numbers[10] = // Describe each digit in terms of display segments 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
{
B11111100,
B01100000,
B11011010,
B11110010,
B01100110,
B10110110,
B10111110,
B11100000,
B11111110,
B11100110,
};
void setup()
{
pinMode(latchPin, OUTPUT); // set SR pins to output
pinMode(clockPin, OUTPUT);
pinMode(dataPin, OUTPUT);
pinMode(upPin, INPUT); // sets pin 12 as pushbutton INPUT
pinMode(downPin, INPUT); // sets pin 13 as pushbutton INPUT
}
void loop()
{
//counter part
//currUpState = digitalRead(upPin); <== NO need for stupid global
if (prevUpState != digitalRead(upPin)) // has the state changed from
{ // HIGH to LOW or vice versa
prevUpState = !prevUpState; //invert
if (currUpState == HIGH && counter < maxCount) // If the button was pressed AND not reached limit
counter++;
//if (counter > 8) counter = 0; // increment the counter by one <=== LIMITS IT TO 8 NOW!
}
/* useless bit of code
if (counter > 8)
counter--;
show(numbers[counter]); // display the current digit
*/
currDownState = digitalRead(downPin);
if (prevDownState != currDownState) // has the state changed from
{ // HIGH to LOW or vice versa
prevDownState = currDownState;
if (currDownState == HIGH && counter > minCount) // If the button was pressed AND not reached limit
counter--; // decrement the counter by one
}
/* weird bit
if (counter < 0)
counter++;
*/
showNumber(counter); // display the current digit
}
void showNumber(int number)
{
/*just a bit weird
// Use a loop and a bitwise AND to move over each bit that makes up
// the seven segment display (from left to right, A => G), and check
// to see if it should be on or not
for (int j = 0; j <= 7; j++)
{
byte toWrite = number & (B10000000 >> j);
if (!toWrite) {
continue;
} // If all bits are 0 then no point writing it to the shift register,so break out and
//move on to next segment.
shiftIt(toWrite); // Otherwise shift it into the register
}
*/
digitalWrite(latchPin, LOW); // Set latchPin LOW while clocking bits in to the register
for(byte i = 0; i < numberOfDigits; i++){
shiftOut(dataPin, clockPin, LSBFIRST, numbers[number % 10]);
number /= 10;
}
digitalWrite(latchPin, HIGH); //set latchPin to high to lock and send data
}
Thanks for explaining that and showing the sample it works great now
Cheers
Greg
Greg, would you mind posting the final code bro?!
Greetings from Brazil!!