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cc4c028 Jan 21, 2015
146 lines (115 sloc) 3.23 KB
const int clock = 7;
const int data = 8;
/*0*/ /*1*/ /*2*/ /*3*/ /*4*/ /*5*/ /*6*/ /*7*/ /*8*/ /*9*/
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();
// clear display
write(0x00, 0x00, 0x00, 0x00);
}
byte tcnt2;
unsigned long time = 0; // 86390000;
// Credits for the interrupt setup routine:
// http://popdevelop.com/2010/04/mastering-timer-interrupts-on-the-arduino/
void setupInterrupt()
{
/* First disable the timer overflow interrupt while we're configuring */
TIMSK2 &= ~(1<<TOIE2);
/* Configure timer2 in normal mode (pure counting, no PWM etc.) */
TCCR2A &= ~((1<<WGM21) | (1<<WGM20));
TCCR2B &= ~(1<<WGM22);
/* Select clock source: internal I/O clock */
ASSR &= ~(1<<AS2);
/* Disable Compare Match A interrupt enable (only want overflow) */
TIMSK2 &= ~(1<<OCIE2A);
/* Now configure the prescaler to CPU clock divided by 128 */
TCCR2B |= (1<<CS22) | (1<<CS20); // Set bits
TCCR2B &= ~(1<<CS21); // Clear bit
/* We need to calculate a proper value to load the timer counter.
* The following loads the value 131 into the Timer 2 counter register
* The math behind this is:
* (CPU frequency) / (prescaler value) = 125000 Hz = 8us.
* (desired period) / 8us = 125.
* MAX(uint8) + 1 - 125 = 131;
*/
/* Save value globally for later reload in ISR */
tcnt2 = 131;
/* Finally load end enable the timer */
TCNT2 = tcnt2;
TIMSK2 |= (1<<TOIE2);
}
/*
* Install the Interrupt Service Routine (ISR) for Timer2 overflow.
* This is normally done by writing the address of the ISR in the
* interrupt vector table but conveniently done by using ISR() */
ISR(TIMER2_OVF_vect) {
/* Reload the timer */
TCNT2 = tcnt2;
time++;
time = time % 86400000;
}
void loop()
{
unsigned long t = (unsigned long)(time/1000);
uint8_t minutes = (byte)((t / 60) % 60);
uint8_t seconds = (byte)(t % 60);
write(digits[minutes / 10], digits[minutes % 10] | ((seconds & 0x01) << 7) , digits[seconds / 10], digits[seconds % 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);//send start signal to TM1637
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);
}
// wait for ACK
digitalWrite(clock,LOW);
delayMicroseconds(5);
pinMode(data,INPUT);
digitalWrite(clock,HIGH);
delayMicroseconds(5);
bool ack = digitalRead(data) == 0;
pinMode(data,OUTPUT);
return ack;
}