Cheapest Arduino LED Clock With Arduino Clone at $8

Abhishek Ghosh

By Abhishek Ghosh March 19, 2017 7:06 am Updated on March 19, 2017

Cheapest Arduino LED Clock With Arduino Clone at $8

Lately we published some guides with basic electronic components. Here is Cheapest Arduino LED Clock Which With Arduino Clone Will Cost $8 To You. It is really usable LED Clock for any purpose, it not only for fun out of development. Commercial clocks will cost more than $10. Basically if the DIY electronic stuff is not cheap, it becomes useless thing. You can use such clocks anywhere but you will always need to supply 9v power to Arduino board. I have not calculated the cost of battery. If you use 4 or 6 AA cells, it will also work. I must inform you that there are kits sold with the name “Electronic Clock DIY Kit Digital Tube” which cost around $12, which are based on Arduino UNO, there is “PIC16F877A Digital Clock Kit” which costs around $8.

In our case advantages are full control of quality of components and the chance to use for other projects in future. There is no disadvantage is that, it is not for real time clock, there is no button control, it is only 24 hours clock. If you want Arduino real time LED clock, you should follow this guide.

Cheapest Arduino LED Clock : Buying the Materials

You simply need to follow our older guides :

Cheapest Arduino clone
TM 1637 LED Display
Optional – TM 1637 LED Display Real Time Clock

Cheapest Arduino LED Clock : Circuit Diagram and Code

The circuit diagram is quite easy, you just need to follow the old guide TM 1637 LED Display. Connecting TM1637 to Arduino:

Arduino              TM1637 display
PIN #7 ------------------ CLK
PIN #8 ------------------ DIO
3.3V   ------------------ VCC
GND    ------------------ GND

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Arduino TM1637 display

PIN #7 ------------------ CLK

PIN #8 ------------------ DIO

3.3V ------------------ VCC

GND ------------------ GND

Real time clock module is optional and 9v battery power supply is what needed. You need an enclosure which can fit the whole stuff nicely. I kept the whole codes here on Github – TM1637-Clock-Arduino, you will use the hour minute clock (or code from below). Too much basic clock but easy for anyone to assemble.

Here is the code. You will set the current time by editing the values at line 16 and 17. Several peoples coded it, I have only adjusted it to correct 23:59 to 00:00 part.

const int clock = 7;
const int data = 8;
uint8_t digits[] = { 0x3f, 0x06, 0x5b, 0x4f, 0x66, 0x6d, 0x7d, 0x07, 0x7f, 0x6f };
void setup()
{
  setupInterrupt();
  pinMode(clock, OUTPUT);
  pinMode(data, OUTPUT);
  start();
  writeValue(0x8c);
  stop();
  write(0x00, 0x00, 0x00, 0x00);
}
byte tcnt2;
  unsigned long setMinutes = 34;
  unsigned long setHours = 23;
  unsigned long time = (setMinutes * 60 * 1000) + (setHours * 3600 *1000);
void setupInterrupt()
{
  TIMSK2 &= ~(1<<TOIE2);
  TCCR2A &= ~((1<<WGM21) | (1<<WGM20));
  TCCR2B &= ~(1<<WGM22);
  ASSR &= ~(1<<AS2);
  TIMSK2 &= ~(1<<OCIE2A);
  TCCR2B |= (1<<CS22)  | (1<<CS20); 
  TCCR2B &= ~(1<<CS21);
  tcnt2 = 131;
  TCNT2 = tcnt2;
  TIMSK2 |= (1<<TOIE2);
}
ISR(TIMER2_OVF_vect) {
  TCNT2 = tcnt2;
  time++;
  time = time % 86400000;
}
void loop()
{
  unsigned long t = (unsigned long)(time/1000);
  uint8_t minutes = (byte)((t / 60) % 60);
  uint8_t hours = (byte)((t / 3600) % 24);
  uint8_t seconds = (byte)(t % 60);
    write(digits[hours / 10], digits[hours % 10] | ((seconds & 0x01) << 7), digits[minutes / 10], digits[minutes % 10]);
}
void write(uint8_t first, uint8_t second, uint8_t third, uint8_t fourth)
{
  start();
  writeValue(0x40);
  stop();
  start();
  writeValue(0xc0);
  writeValue(first);
  writeValue(second);
  writeValue(third);
  writeValue(fourth);
  stop();
}
void start(void)
{
  digitalWrite(clock,HIGH);
  digitalWrite(data,HIGH);
  delayMicroseconds(5);
  digitalWrite(data,LOW);
  digitalWrite(clock,LOW);
  delayMicroseconds(5);
}
void stop(void)
{
  digitalWrite(clock,LOW);
  digitalWrite(data,LOW);
  delayMicroseconds(5);

  digitalWrite(clock,HIGH);
  digitalWrite(data,HIGH);
  delayMicroseconds(5);
}
bool writeValue(uint8_t value)
{
  for(uint8_t i = 0; i < 8; i++)
  {
    digitalWrite(clock, LOW);
    delayMicroseconds(5);
    digitalWrite(data, (value & (1 << i)) >> i);
    delayMicroseconds(5);
    digitalWrite(clock, HIGH);
    delayMicroseconds(5);
  }
  digitalWrite(clock,LOW);
  delayMicroseconds(5);
  pinMode(data,INPUT);
  digitalWrite(clock,HIGH);
  delayMicroseconds(5);
  bool ack = digitalRead(data) == 0;
  pinMode(data,OUTPUT);
  return ack;
}

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const int clock = 7;

const int data = 8;

uint8_t digits[] = { 0x3f, 0x06, 0x5b, 0x4f, 0x66, 0x6d, 0x7d, 0x07, 0x7f, 0x6f };

void setup()

{

setupInterrupt();

pinMode(clock, OUTPUT);

pinMode(data, OUTPUT);

start();

writeValue(0x8c);

stop();

write(0x00, 0x00, 0x00, 0x00);

}

byte tcnt2;

unsigned long setMinutes = 34;

unsigned long setHours = 23;

unsigned long time = (setMinutes * 60 * 1000) + (setHours * 3600 *1000);

void setupInterrupt()

{

TIMSK2 &= ~(1<<TOIE2);

TCCR2A &= ~((1<<WGM21) | (1<<WGM20));

TCCR2B &= ~(1<<WGM22);

ASSR &= ~(1<<AS2);

TIMSK2 &= ~(1<<OCIE2A);

TCCR2B |= (1<<CS22) | (1<<CS20);

TCCR2B &= ~(1<<CS21);

tcnt2 = 131;

TCNT2 = tcnt2;

TIMSK2 |= (1<<TOIE2);

}

ISR(TIMER2_OVF_vect) {

TCNT2 = tcnt2;

time++;

time = time % 86400000;

}

void loop()

{

unsigned long t = (unsigned long)(time/1000);

uint8_t minutes = (byte)((t / 60) % 60);

uint8_t hours = (byte)((t / 3600) % 24);

uint8_t seconds = (byte)(t % 60);

write(digits[hours / 10], digits[hours % 10] | ((seconds & 0x01) << 7), digits[minutes / 10], digits[minutes % 10]);

}

void write(uint8_t first, uint8_t second, uint8_t third, uint8_t fourth)

{

start();

writeValue(0x40);

stop();

start();

writeValue(0xc0);

writeValue(first);

writeValue(second);

writeValue(third);

writeValue(fourth);

stop();

}

void start(void)

{

digitalWrite(clock,HIGH);

digitalWrite(data,HIGH);

delayMicroseconds(5);

digitalWrite(data,LOW);

digitalWrite(clock,LOW);

delayMicroseconds(5);

}

void stop(void)

{

digitalWrite(clock,LOW);

digitalWrite(data,LOW);

delayMicroseconds(5);

digitalWrite(clock,HIGH);

digitalWrite(data,HIGH);

delayMicroseconds(5);

}

bool writeValue(uint8_t value)

{

for(uint8_t i = 0; i < 8; i++)

{

digitalWrite(clock, LOW);

delayMicroseconds(5);

digitalWrite(data, (value & (1 << i)) >> i);

delayMicroseconds(5);

digitalWrite(clock, HIGH);

delayMicroseconds(5);

}

digitalWrite(clock,LOW);

delayMicroseconds(5);

pinMode(data,INPUT);

digitalWrite(clock,HIGH);

delayMicroseconds(5);

bool ack = digitalRead(data) == 0;

pinMode(data,OUTPUT);

return ack;

}

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Cheapest Arduino LED Clock With Arduino Clone at $8

Cheapest Arduino LED Clock : Buying the Materials

Cheapest Arduino LED Clock : Circuit Diagram and Code

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About Abhishek Ghosh

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