Mit dem alten Bubble-LED-Chip 5082-7415 von Hewlett Packard (kurz HP) und einer Real-time-clock (kurz RTC, konkret das Modell DS3231) lässt sich auf Arduino-Basis eine einfache Retrouhr im Stile der 70er Jahre basteln. Die Schaltung benötigt neben dem LED-Chip nur noch einige Widerstände und npn-Transistoren etwa vom Typ BC547.
Diese Bubble-LED-Chips wurden früher zum Beispiel in Taschenrechnern eingesetzt. Ich habe meinen Chip auf ebay für rund 14 Euro erstanden.
Bildquelle: https://tronixstuff.com/2025/04/11/hewlett-packard-5082-7415-led-display-from-1976/
Arduino-Code:
#include <Wire.h>
#define DS3231_I2C_ADDRESS 104
// SCL - pin A5
// SDA - pin A4
// To set the clock, run the sketch and use the serial monitor.
// Enter T1124154091014; the code will read this and set the clock. See the code for full details.
//
byte seconds, minutes, hours, day, date, month, year;
byte seconds_e, minutes_e, minutes_z, hours_e, hours_z;
char weekDay[4];
byte tMSB, tLSB;
float temp3231;
int Anzeigendauer;
//==============================
//=========== SETUP ============
//==============================
void setup()
{
Wire.begin();
Serial.begin(9600);
for (int i = 2; i < 14;i++)
{
pinMode(i, OUTPUT);
}
digitalWrite(9,LOW);
digitalWrite(10,LOW);
digitalWrite(11,LOW);
digitalWrite(12,LOW);
digitalWrite(13,LOW);
Anzeigendauer = 4;
}
//======================================
//=========== HAUPTSCHLEIFE ============
//======================================
void loop()
{
watchConsole();
get3231Date();
/*
Serial.print(weekDay);
Serial.print(", ");
Serial.print(date, DEC);
Serial.print("/");
Serial.print(month, DEC);
Serial.print("/");
Serial.print(year, DEC);
Serial.print(" - ");
Serial.print(hours, DEC);
Serial.print(":");
Serial.print(minutes, DEC);
Serial.print(":");
Serial.print(seconds, DEC);
Serial.print(" - Temp: ");
Serial.println(get3231Temp());
*/
// Bestimmung der Einer- und Zehnerstellen der Minuten und Stunden
// ===============================================================
seconds_e = (seconds%10);
minutes_e = (minutes%10);
minutes_z = (minutes%100)/10;
hours_e = (hours%10);
hours_z = (hours%100)/10;
if (hours_z > 0)
{
Anzeige(hours_z); // Darstellung der Stunden-Zehnerstelle
digitalWrite(9,HIGH);
delay(Anzeigendauer);
digitalWrite(9,LOW);
}
Anzeige(hours_e); // Darstellung der Stunden-Einerstelle
digitalWrite(10,HIGH);
delay(Anzeigendauer);
digitalWrite(10,LOW);
if ((seconds_e%2) == 0) // Darstellung eines Querstrichs alle geraden Sekunden
{
Anzeige(16);
digitalWrite(11,HIGH);
delay(Anzeigendauer);
digitalWrite(11,LOW);
}
Anzeige(minutes_z); // Darstellung der Minuten-Zehnerstelle
digitalWrite(12,HIGH);
delay(Anzeigendauer);
digitalWrite(12,LOW);
Anzeige(minutes_e); // Darstellung der Minuten-Einerstelle
digitalWrite(13,HIGH);
delay(Anzeigendauer);
digitalWrite(13,LOW);
}
void Anzeige(int Ziffer)
{
switch (Ziffer)
{
case 0: // Darstellung der Ziffer 0
digitalWrite(2,HIGH);
digitalWrite(3,HIGH);
digitalWrite(4,HIGH);
digitalWrite(5,HIGH);
digitalWrite(6,HIGH);
digitalWrite(7,HIGH);
digitalWrite(8,LOW);
break;
case 1: // Darstellung der Ziffer 1
digitalWrite(2,LOW);
digitalWrite(3,HIGH);
digitalWrite(4,HIGH);
digitalWrite(5,LOW);
digitalWrite(6,LOW);
digitalWrite(7,LOW);
digitalWrite(8,LOW);
break;
case 2: // Darstellung der Ziffer 2
digitalWrite(2,HIGH);
digitalWrite(3,HIGH);
digitalWrite(4,LOW);
digitalWrite(5,HIGH);
digitalWrite(6,HIGH);
digitalWrite(7,LOW);
digitalWrite(8,HIGH);
break;
case 3: // Darstellung der Ziffer 3
digitalWrite(2,HIGH);
digitalWrite(3,HIGH);
digitalWrite(4,HIGH);
digitalWrite(5,HIGH);
digitalWrite(6,LOW);
digitalWrite(7,LOW);
digitalWrite(8,HIGH);
break;
case 4: // Darstellung der Ziffer 4
digitalWrite(2,LOW);
digitalWrite(3,HIGH);
digitalWrite(4,HIGH);
digitalWrite(5,LOW);
digitalWrite(6,LOW);
digitalWrite(7,HIGH);
digitalWrite(8,HIGH);
break;
case 5: // Darstellung der Ziffer 5
digitalWrite(2,HIGH);
digitalWrite(3,LOW);
digitalWrite(4,HIGH);
digitalWrite(5,HIGH);
digitalWrite(6,LOW);
digitalWrite(7,HIGH);
digitalWrite(8,HIGH);
break;
case 6: // Darstellung der Ziffer 6
digitalWrite(2,HIGH);
digitalWrite(3,LOW);
digitalWrite(4,HIGH);
digitalWrite(5,HIGH);
digitalWrite(6,HIGH);
digitalWrite(7,HIGH);
digitalWrite(8,HIGH);
break;
case 7: // Darstellung der Ziffer 7
digitalWrite(2,HIGH);
digitalWrite(3,HIGH);
digitalWrite(4,HIGH);
digitalWrite(5,LOW);
digitalWrite(6,LOW);
digitalWrite(7,LOW);
digitalWrite(8,LOW);
break;
case 8: // Darstellung der Ziffer 8
digitalWrite(2,HIGH);
digitalWrite(3,HIGH);
digitalWrite(4,HIGH);
digitalWrite(5,HIGH);
digitalWrite(6,HIGH);
digitalWrite(7,HIGH);
digitalWrite(8,HIGH);
break;
case 9: // Darstellung der Ziffer 9
digitalWrite(2,HIGH);
digitalWrite(3,HIGH);
digitalWrite(4,HIGH);
digitalWrite(5,HIGH);
digitalWrite(6,LOW);
digitalWrite(7,HIGH);
digitalWrite(8,HIGH);
break;
case 16: // Darstellung des Querstrichs
digitalWrite(2,LOW);
digitalWrite(3,LOW);
digitalWrite(4,LOW);
digitalWrite(5,LOW);
digitalWrite(6,LOW);
digitalWrite(7,LOW);
digitalWrite(8,HIGH);
break;
}
}
// Convert normal decimal numbers to binary coded decimal
byte decToBcd(byte val)
{
return ( (val/10*16) + (val%10) );
}
void watchConsole()
{
if (Serial.available())
{ // Look for char in serial queue and process if found
if (Serial.read() == 84)
{ //If command = "T" Set Date
set3231Date();
get3231Date();
Serial.println(" ");
}
}
}
void set3231Date()
{
//T(sec)(min)(hour)(dayOfWeek)(dayOfMonth)(month)(year)
//T(00-59)(00-59)(00-23)(1-7)(01-31)(01-12)(00-99)
//Example: 02-Okt-15 @ 19:57:11 for the 3rd day of the week -> T1157193021015
seconds = (byte) ((Serial.read() - 48) * 10 + (Serial.read() - 48)); // Use of (byte) type casting and ascii math to achieve result.
minutes = (byte) ((Serial.read() - 48) *10 + (Serial.read() - 48));
hours = (byte) ((Serial.read() - 48) *10 + (Serial.read() - 48));
day = (byte) (Serial.read() - 48);
date = (byte) ((Serial.read() - 48) *10 + (Serial.read() - 48));
month = (byte) ((Serial.read() - 48) *10 + (Serial.read() - 48));
year = (byte) ((Serial.read() - 48) *10 + (Serial.read() - 48));
Wire.beginTransmission(DS3231_I2C_ADDRESS);
Wire.write(0x00);
Wire.write(decToBcd(seconds));
Wire.write(decToBcd(minutes));
Wire.write(decToBcd(hours));
Wire.write(decToBcd(day));
Wire.write(decToBcd(date));
Wire.write(decToBcd(month));
Wire.write(decToBcd(year));
Wire.endTransmission();
}
void get3231Date()
{
// send request to receive data starting at register 0
Wire.beginTransmission(DS3231_I2C_ADDRESS); // 104 is DS3231 device address
Wire.write(0x00); // start at register 0
Wire.endTransmission();
Wire.requestFrom(DS3231_I2C_ADDRESS, 7); // request seven bytes
if(Wire.available())
{
seconds = Wire.read(); // get seconds
minutes = Wire.read(); // get minutes
hours = Wire.read(); // get hours
day = Wire.read();
date = Wire.read();
month = Wire.read(); //temp month
year = Wire.read();
seconds = (((seconds & B11110000)>>4)*10 + (seconds & B00001111)); // convert BCD to decimal
minutes = (((minutes & B11110000)>>4)*10 + (minutes & B00001111)); // convert BCD to decimal
hours = (((hours & B00110000)>>4)*10 + (hours & B00001111)); // convert BCD to decimal (assume 24 hour mode)
day = (day & B00000111); // 1-7
date = (((date & B00110000)>>4)*10 + (date & B00001111)); // 1-31
month = (((month & B00010000)>>4)*10 + (month & B00001111)); //msb7 is century overflow
year = (((year & B11110000)>>4)*10 + (year & B00001111));
}
else
{
//oh noes, no data!
}
switch (day)
{
case 1:
strcpy(weekDay, "Mo");
break;
case 2:
strcpy(weekDay, "Di");
break;
case 3:
strcpy(weekDay, "Mi");
break;
case 4:
strcpy(weekDay, "Do");
break;
case 5:
strcpy(weekDay, "Fr");
break;
case 6:
strcpy(weekDay, "Sa");
break;
case 7:
strcpy(weekDay, "So");
break;
}
}
float get3231Temp()
{
//temp registers (11h-12h) get updated automatically every 64s
Wire.beginTransmission(DS3231_I2C_ADDRESS);
Wire.write(0x11);
Wire.endTransmission();
Wire.requestFrom(DS3231_I2C_ADDRESS, 2);
if(Wire.available())
{
tMSB = Wire.read(); //2's complement int portion
tLSB = Wire.read(); //fraction portion
temp3231 = (tMSB & B01111111); //do 2's math on Tmsb
temp3231 += ( (tLSB >> 6) * 0.25 ); //only care about bits 7 & 8
}
else
{
//oh noes, no data!
}
return temp3231;
}
