After sorting out how works 16 bit hardware timer it is time for 4 digits countdown timer. Having 16 bit timer and 7 segments LED code from earlier only were remaining to write timer’s modes (run/setup) and button’s control code. After putting all code to one place there is countdown timer with properties below:
- Maximum 99 minutes 59 seconds countdown interval
- 1 second resolution
- Sound indication with buzzer for finished countdown
- LED indicates running timer, or relay instead for powering external devices for some period of time
- 2 buttons to set timer and start/pause/reset.
This time without additional code quotation, please find some code explanation within code, so code bellow.
/* Arduino 4 digits 7 segments LED countdown timer with buzzerm from electronicsblog.net. If You share/use this code elsewhere on the internet please meantion this code source. */ // segment | Arduino board PIN number #define G 22 #define F 23 #define A 24 #define B 25 #define E 26 #define D 27 #define C 28 #define DP 29 // Commonn cathodes control #define GND1 52 #define GND2 53 #define GND3 50 #define GND4 51 // buttons /* Button_start - start/pause timer and in setup mode inreases minutes and seconds values Button_set - if timer is paused it resets timer to start. Long press activates setup mode in which button is for going through minutes, seconds setup and leaving setup mode. */ #define Button_start 48 #define Button_set 49 /// #define Buzzer 46 #define LED 47 // or relay insted int i=0; char run=0; // shows if timer is runnig int b=0; //for buttons int c=0; int d=0; // for buzzer char set_mode=0; // shows if timer is in setup mode char alarm =0; // if "1" buzzer is on //timer variables // user setted and "turn on" values int default_Sec=59; int default_Min=99; // current values int Sec; int Min; //timer interrupt ISR(TIMER1_OVF_vect) { Sec--; // timer values decreases TCNT1=0x0BDC; } // functions to display digits void digit0 () { // for 0 needed to turn ON F A B C D E segments, so: digitalWrite(A, HIGH); digitalWrite(B, HIGH); digitalWrite(C, HIGH); digitalWrite(D, HIGH); digitalWrite(E, HIGH); digitalWrite(F, HIGH); //////////////////////// G segment should be turn OFF digitalWrite(G, LOW); }; void digit1 () { digitalWrite(A,LOW); digitalWrite(B, HIGH); digitalWrite(C, HIGH); digitalWrite(D, LOW); digitalWrite(E, LOW); digitalWrite(F, LOW); digitalWrite(G, LOW); }; void digit2 () { digitalWrite(A,HIGH); digitalWrite(B, HIGH); digitalWrite(C, LOW); digitalWrite(D, HIGH); digitalWrite(E, HIGH); digitalWrite(F, LOW); digitalWrite(G, HIGH); }; void digit3 () { digitalWrite(A,HIGH); digitalWrite(B, HIGH); digitalWrite(C, HIGH); digitalWrite(D, HIGH); digitalWrite(E, LOW); digitalWrite(F, LOW); digitalWrite(G, HIGH); }; void digit4 () { digitalWrite(A,LOW); digitalWrite(B, HIGH); digitalWrite(C, HIGH); digitalWrite(D, LOW); digitalWrite(E, LOW); digitalWrite(F, HIGH); digitalWrite(G, HIGH); }; void digit5 () { digitalWrite(A,HIGH); digitalWrite(B, LOW); digitalWrite(C, HIGH); digitalWrite(D, HIGH); digitalWrite(E, LOW); digitalWrite(F, HIGH); digitalWrite(G, HIGH); }; void digit6 () { digitalWrite(A,HIGH); digitalWrite(B, LOW); digitalWrite(C, HIGH); digitalWrite(D, HIGH); digitalWrite(E, HIGH); digitalWrite(F, HIGH); digitalWrite(G, HIGH); }; void digit7 () { digitalWrite(A,HIGH); digitalWrite(B, HIGH); digitalWrite(C, HIGH); digitalWrite(D, LOW); digitalWrite(E, LOW); digitalWrite(F, LOW); digitalWrite(G, LOW); }; void digit8 () { digitalWrite(A, HIGH); digitalWrite(B, HIGH); digitalWrite(C, HIGH); digitalWrite(D, HIGH); digitalWrite(E, HIGH); digitalWrite(F, HIGH); digitalWrite(G, HIGH); }; void digit9 () { digitalWrite(A, HIGH); digitalWrite(B, HIGH); digitalWrite(C, HIGH); digitalWrite(D, HIGH); digitalWrite(E, LOW); digitalWrite(F, HIGH); digitalWrite(G, HIGH); }; //function to display digit from inputed int void showdigit (int digit) { switch (digit) { case 0: digit0 (); break; case 1: digit1 (); break; case 2: digit2 (); break; case 3: digit3 (); break; case 4: digit4 (); break; case 5: digit5 (); break; case 6: digit6 (); break; case 7: digit7 (); break; case 8: digit8 (); break; case 9: digit9 (); break; default: break; }; }; // showing 4 digits // not only shows 4 digit number, but also there is option to turn on //only selected digits and decimal point. void showdigits (int number, char digit_on, char decimal_point) { digitalWrite(GND4, LOW); // e.g. we have "1234" showdigit(number/1000); // segments are set to display "1" if (decimal_point&8) {digitalWrite(DP, HIGH);} else {digitalWrite(DP, LOW);}; if (digit_on&8) { digitalWrite(GND1, HIGH); // first digit on, digitalWrite(GND2, LOW); // other off digitalWrite(GND3, LOW); } delay (1); number = number%1000; // remainder of 1234/1000 is 234 digitalWrite(GND1, LOW); // first digit is off showdigit(number/100); //// segments are set to display "2" if (decimal_point&4) {digitalWrite(DP, HIGH);} else {digitalWrite(DP, LOW);}; if (digit_on&4) { digitalWrite(GND2, HIGH); // second digit is on } delay (1);// and so on.... number =number%100; digitalWrite(GND2, LOW); showdigit(number/10); if (decimal_point&2) {digitalWrite(DP, HIGH);} else {digitalWrite(DP, LOW);}; if (digit_on&2) { digitalWrite(GND3, HIGH); } delay (1); number =number%10; digitalWrite(GND3, LOW); showdigit(number); if (decimal_point&1) {digitalWrite(DP, HIGH);} else {digitalWrite(DP, LOW);}; if (digit_on&1) { digitalWrite(GND4, HIGH); } delay (1); }; void setup() { pinMode(A, OUTPUT); pinMode(B, OUTPUT); pinMode(C, OUTPUT); pinMode(D, OUTPUT); pinMode(E, OUTPUT); pinMode(F, OUTPUT); pinMode(G, OUTPUT); pinMode(DP, OUTPUT); pinMode(GND1, OUTPUT); pinMode(GND2, OUTPUT); pinMode(GND3, OUTPUT); pinMode(GND4, OUTPUT); pinMode(Button_start, INPUT); digitalWrite(Button_start, HIGH); //pull up resistor pinMode(Button_set, INPUT); digitalWrite(Button_set, HIGH); //pull up resistor pinMode(Buzzer, OUTPUT); pinMode(LED, OUTPUT); TIMSK1=0x01; // enabled global and timer overflow interrupt; TCCR1A = 0x00; // normal operation 148 page (mode0); TCNT1=0x0BDC; TCCR1B = 0x00; // stop hardware timer // loading default timer values Sec = default_Sec ; Min = default_Min ; }; void loop () { //////////// button_start////////// if (!digitalRead(Button_start)&&!b) { if (!set_mode) { if (run) {TCCR1B=0x00; run=0;} else {TCCR1B=0x04; run=1;}} if (set_mode==1) {Min++;} if (set_mode==2) {Sec++;} if (set_mode) {b=25;} else b=100; }; if (!digitalRead(Button_start)&&b==1) { }; if (!b==0) b--; //////////// button_set///////// if (!digitalRead(Button_set)&&!c) { if(!run&&!set_mode) {Min=default_Min; Sec=default_Sec;} if (set_mode>0) set_mode++; if (set_mode==3) {set_mode=0; default_Sec = Sec ; default_Min = Min; } c=100; }; if (!digitalRead(Button_set)&&c==1&&!run) { set_mode=1; c=100; }; if (!c==0) c--; //////////////////////////// if (set_mode) {if (Sec==60) {Sec=00;} if (Min==100) {Min=0;} } else { if (Sec==-1) {Min--;Sec=59;} } //decimal point indication control if (!set_mode) { if (!(Sec%2)) { showdigits (Min*100+Sec,0x0F,0x04); } //0X00 else {showdigits (Min*100+Sec,0x0F,0x00); }; //0000 } else { if (set_mode==1) { showdigits (Min*100+Sec,0x0F,0x0C); //XX00 } else { showdigits (Min*100+Sec,0x0F,0x03); } //00XX } if (run) { // to do while timer is running; e.g. control relay digitalWrite(LED, HIGH); } else digitalWrite(LED, LOW); if ((Min==0)&&(Sec==0)&&run) { run=0; TCCR1B=0x00; //stop timer //// to do after count down is finished e.g. start alarm as in this example alarm=1; d=500; } // Alarm part if (alarm) { if (!(d%100)) { // sound 500/100= 5 times ; tone(Buzzer, 440, 200); } d--; if (d==0) {alarm=0; Sec = default_Sec ; Min = default_Min ; // After alarm is off, timer goes to start } } };
