Hi,
I started coding my new project. Code works as I excpeted, but I decided to use 9 7-segment displays instead of 4 and displays started flickering. I know it happens due to too low refresh frequency. But at this moment I don’t understand timers and interrupts. How to simply increase Timer1 frequency to arodund 2KHz ? Thanks.
/*
* Matural Exam Countdown Clock
* By Filip Cichowski
* CC 2020
*/
// counter button definition
#define dayplus A1
#define dayminus A0
#define hourplus A3
#define hourminus A2
#define grade1 A4
#define grade2 A5
#define grade3 A6
// shift register pin definitions
#define clockPin 13 // clock pin
#define dataPin 12 // data pin
// common pins of the four digits definitions
#define Dig1 5
#define Dig2 4
#define Dig3 3
#define Dig4 2
#define Dig5 6
#define Dig6 7
#define Dig7 8
#define Dig8 9
#define Dig9 10
// variable declarations
byte current_digit;
int days = 234;
int hours;
void disp(byte number, bool dec_point = 0);
unsigned long startMillis;
unsigned long currentMillis;
const unsigned long period = 1000;
void setup()
{
pinMode(dayplus, INPUT_PULLUP);
pinMode(dayminus, INPUT_PULLUP);
pinMode(hourplus, INPUT_PULLUP);
pinMode(hourminus, INPUT_PULLUP);
pinMode(Dig1, OUTPUT);
pinMode(Dig2, OUTPUT);
pinMode(Dig3, OUTPUT);
pinMode(Dig4, OUTPUT);
pinMode(Dig5, OUTPUT);
pinMode(Dig6, OUTPUT);
pinMode(Dig7, OUTPUT);
pinMode(Dig8, OUTPUT);
pinMode(Dig9, OUTPUT);
pinMode(clockPin, OUTPUT);
pinMode(dataPin, OUTPUT);
disp_off(); // turn off the display
// Timer1 module overflow interrupt configuration
TCCR1A = 0;
TCCR1B = 1; // enable Timer1 with prescaler = 1 ( 16 ticks each 1 µs)
TCNT1 = 0; // set Timer1 preload value to 0 (reset)
TIMSK1 = 1; // enable Timer1 overflow interrupt
}
ISR(TIMER1_OVF_vect) // Timer1 interrupt service routine (ISR)
{
disp_off(); // turn off the display
switch (current_digit)
{
case 1:
disp(days / 1000); // prepare to display digit 1 (most left)
digitalWrite(Dig1, LOW); // turn on digit 1
delay(1);
break;
case 2:
disp( (days / 100) % 10 ); // prepare to display digit 2
digitalWrite(Dig2, LOW); // turn on digit 2
delay(1);
break;
case 3:
disp( (days / 10) % 10 ); // prepare to display digit 3
digitalWrite(Dig3, LOW); // turn on digit 3
delay(1);
break;
case 4:
disp(days % 10); // prepare to display digit 4
digitalWrite(Dig4, LOW); // turn on digit 4
delay(1);
break;
case 5:
disp(hours / 10000); // prepare to display digit 5
digitalWrite(Dig5, LOW); // turn on digit 5
delay(1);
break;
case 6:
disp((hours / 1000) % 10); // prepare to display digit 6
digitalWrite(Dig6,LOW); // turn on digit 6
delay(1);
break;
case 7:
disp( (hours / 100) % 10 ); // prepare to display digit 7
digitalWrite(Dig7,LOW); // turn on digit 7
delay(1);
break;
case 8:
disp( (hours / 10) % 10 ); // prepare to display digit 8
digitalWrite(Dig8,LOW); // turn on digit 8
delay(1);
break;
case 9:
disp(hours % 10); // prepare to display digit 9 (most right)
digitalWrite(Dig9,LOW); // turn on digit 9
delay(1);
}
current_digit = (current_digit % 9) + 1;
}
void loop()
{
currentMillis = millis(); //get the current "time" (actually the number of milliseconds since the program started)
if (currentMillis - startMillis >= period) //test whether the period has elapsed
{
days--;
hours = days * 24;
startMillis = currentMillis;
}
if(digitalRead(dayplus) == 0)
{
days++;
if(days > 9999)
days = 0;
delay(150);
}
if(digitalRead(dayminus) == 0)
{
days--;
if(days < 0)
days = 0;
delay(150);
}
/*if(digitalRead(hourplus) == 0)
{
hours++; // increment 'count' by 1
if(hours > 99999)
hours = 0;
delay(150); // wait 200 milliseconds
}
if(digitalRead(hourminus) == 0)
{
hours--; // decrement 'count' by 1
if(hours < 0)
hours = 0;
delay(150); // wait 200 milliseconds
}*/
}
void disp(byte number, bool dec_point)
{
switch (number)
{
case 0: // print 0
shiftOut(dataPin, clockPin, MSBFIRST, 0x02 | !dec_point);
digitalWrite(clockPin, HIGH);
digitalWrite(clockPin, LOW);
break;
case 1: // print 1
shiftOut(dataPin, clockPin, MSBFIRST, 0x9E | !dec_point);
digitalWrite(clockPin, HIGH);
digitalWrite(clockPin, LOW);
break;
case 2: // print 2
shiftOut(dataPin, clockPin, MSBFIRST, 0x24 | !dec_point);
digitalWrite(clockPin, HIGH);
digitalWrite(clockPin, LOW);
break;
case 3: // print 3
shiftOut(dataPin, clockPin, MSBFIRST, 0x0C | !dec_point);
digitalWrite(clockPin, HIGH);
digitalWrite(clockPin, LOW);
break;
case 4: // print 4
shiftOut(dataPin, clockPin, MSBFIRST, 0x98 | !dec_point);
digitalWrite(clockPin, HIGH);
digitalWrite(clockPin, LOW);
break;
case 5: // print 5
shiftOut(dataPin, clockPin, MSBFIRST, 0x48 | !dec_point);
digitalWrite(clockPin, HIGH);
digitalWrite(clockPin, LOW);
break;
case 6: // print 6
shiftOut(dataPin, clockPin, MSBFIRST, 0x40 | !dec_point);
digitalWrite(clockPin, HIGH);
digitalWrite(clockPin, LOW);
break;
case 7: // print 7
shiftOut(dataPin, clockPin, MSBFIRST, 0x1E | !dec_point);
digitalWrite(clockPin, HIGH);
digitalWrite(clockPin, LOW);
break;
case 8: // print 8
shiftOut(dataPin, clockPin, MSBFIRST, !dec_point);
digitalWrite(clockPin, HIGH);
digitalWrite(clockPin, LOW);
break;
case 9: // print 9
shiftOut(dataPin, clockPin, MSBFIRST, 0x08 | !dec_point);
digitalWrite(clockPin, HIGH);
digitalWrite(clockPin, LOW);
}
}
void disp_off()
{
digitalWrite(Dig1, HIGH);
digitalWrite(Dig2, HIGH);
digitalWrite(Dig3, HIGH);
digitalWrite(Dig4, HIGH);
digitalWrite(Dig5, HIGH);
digitalWrite(Dig6, HIGH);
digitalWrite(Dig7, HIGH);
digitalWrite(Dig8, HIGH);
digitalWrite(Dig9, HIGH);
}
// end of code.
