Help with an LED clock code

[Maker]

For ages now I've wanted to make a clock from a ring of 60 full colour LEDs with different colours to represent the hour, minute and second hands (If that makes sense). The problem is I don't know how.

I was thinking of multiplexing as explained in these videos:

Connect all the cathodes for each colour (Using common anode LEDs) to each other with a transistor to connect them to GND (such that by changing which transistor is powered, the colours would change) and wire the 60 anodes to a 6x10 grid of transistors, then connect these 6 and 10 sides to another two grids of 3x2 and 5x2 so that only 15 μC pins are needed. It sounds simple in my head but then I've got no idea how write an Arduino sketch to run it.


Can someone help me understand how to write the code?

Or would an alternative method be better? Like a crapload of shift registers?


(Please don't go off topic talking about Ahmed Mohamed)

 

[Tinbasherdan]

For ages now I've wanted to make a clock from a ring of 60 full colour LEDs with different colours to represent the hour, minute and second hands (If that makes sense). The problem is I don't know how.

I was thinking of multiplexing as explained in these videos:

Connect all the cathodes for each colour (Using common anode LEDs) to each other with a transistor to connect them to GND (such that by changing which transistor is powered, the colours would change) and wire the 60 anodes to a 6x10 grid of transistors, then connect these 6 and 10 sides to another two grids of 3x2 and 5x2 so that only 15 μC pins are needed. It sounds simple in my head but then I've got no idea how write an Arduino sketch to run it.


Can someone help me understand how to write the code?

Or would an alternative method be better? Like a crapload of shift registers?


(Please don't go off topic talking about Ahmed Mohamed)

I was literally just about to say don't take it to school!

 

[the snooper]

like this one

 

[Maker]

like this one

Yep, just like that.

 

[Wendelspanswick]

I have a limited knowledge of Python, C and Assembly language and I am happy modifying existing routines but when it comes to new problems I start to struggle. All problems can be reduced to a mathematical formula and its getting that formula working on paper that I struggle with.
As an example for about the last 10 years I have been struggling with the formula for a badminton scorer that not only keeps track of the score but indicates who's serve it is and from which quadrant of the court, for both singles and doubles games, every winter I go back and tinker with it!

I did find an excellent routine that will drive both CC and CA LEDS, I will dig out the link.

 

[ajlelectronics]

http://playground.arduino.cc/Code/I2CPortExpander8574

 

[Master-of-none]

Possibly some inspiration and/or help here: https://hackaday.io/project/1919-stargate-led-clock
Lots of other clock designs on Hackaday.com

 

[Kayos]

I have a truly ancient book on "advanced digital electronics" from many many many years ago, most advanced thing is a transistor, would be fun/infuriating (delete as applicable) to make it from discrete components

 

[rikrobson]

He easiest way is to address each led as if it were in an 8 x 8 grid. This will need a micro controller with 16 digital outputs. Then you have 8 bytes representing each one with a bit. Obviously there are 4 spare bits.
Then loop through each byte on the corresponding output.
I'm out tonight but can explain better tomorrow

 

[Maker]

All problems can be reduced to a mathematical formula and its getting that formula working on paper that I struggle with.

That inspired me, thanks a lot.


Though it turns out it's very hard to make such a formula but I had a general studies "lesson" so I figured out a way with a load of if statements. It could be quite easily shortened I think and I haven't looked for bugs in it yet but it works in my head.

int A; // Cathode select
int B; // Grid 1 A select
int C; // Grid 1 B select
int D; // Grid 2 A select
int E; // Grid 2 B select
int F; // LED address
int G; // F divisor
int H; // Grid 3 row select
int I; // H divisor
int Second = 0;
int Minute = 0;
int MinuteH = 0;
int Hour = 0;

void setup() {
}


void loop() {

Second = Second + 1;

if(Second == 60){
Minute = Minute + 1;
MinuteH = MinuteH +1;
Second = 0;
}
if(Minute == 60){
Minute = 0;
}
if(MinuteH == 12){
Hour = Hour + 1;
}
if(Hour == 60){
Hour = 0;
}


for(int X = 0; X <= 2; X++){
if(X == 0){
Second = F;
digitalWrite(0, HIGH);
}
if(X == 1){
Minute = F;
digitalWrite(1, HIGH);

}
if(X == 2){
Hour = F;
digitalWrite(2, HIGH);
}

if(F <= 50){
H = 5;
I = 40;
}
if(F <= 40){
H = 4;
I = 30;
}
if(F <= 60){
H = 6;
I = 50;
}
if(F <= 30){
H = 3;
I = 20;
}
if(F <= 20){
H = 2;
I = 10;
}
if(F <= 10){
H = 1;
I = 0;
}

if(H == 1){
digitalWrite(10, HIGH);
digitalWrite(13, HIGH);
}
if(H == 2){
digitalWrite(11, HIGH);
digitalWrite(13, HIGH);
}
if(H == 3){
digitalWrite(12, HIGH);
digitalWrite(13, HIGH);
}
if(H == 4){
digitalWrite(10, HIGH);
digitalWrite(14, HIGH);
}
if(H == 5){
digitalWrite(11, HIGH);
digitalWrite(13, HIGH);
}
if(H == 6){
digitalWrite(12, HIGH);
digitalWrite(13, HIGH);
}

F = F-I;

if(F == 0){
digitalWrite(3, HIGH);
digitalWrite(8, HIGH);
}
if(F == 1){
digitalWrite(4, HIGH);
digitalWrite(8, HIGH);
}
if(F == 2){
digitalWrite(5, HIGH);
digitalWrite(8, HIGH);
}
if(F == 3){
digitalWrite(6, HIGH);
digitalWrite(8, HIGH);
}
if(F == 4){
digitalWrite(7, HIGH);
digitalWrite(8, HIGH);
}
if(F == 5){
digitalWrite(3, HIGH);
digitalWrite(9, HIGH);
}
if(F == 6){
digitalWrite(4, HIGH);
digitalWrite(9, HIGH);
}
if(F == 7){
digitalWrite(5, HIGH);
digitalWrite(9, HIGH);
}
if(F == 8){
digitalWrite(6, HIGH);
digitalWrite(9, HIGH);
}
if(F == 9){
digitalWrite(7, HIGH);
digitalWrite(9, HIGH);
}
}
}

It makes sense to me, I'm sure all you experienced people will get a good laugh out of it.

I have a truly ancient book on "advanced digital electronics" from many many many years ago, most advanced thing is a transistor, would be fun/infuriating (delete as applicable) to make it from discrete components

Fun, definitely fun. How though, I've got no idea.

 

[eSCHEn]

Nowt to laugh at buddy. You can neaten and shorten it up a bit of you're interested though?

 

[Maker]

You can neaten and shorten it up a bit of you're interested though?

How's this;

int A; // Cathode select
int B; // Grid 1 A select
int C; // Grid 1 B select
int D; // Grid 2 A select
int E; // Grid 2 B select
int F; // LED address

int Second = 0; // Time
int Minute = 0; // Time
int MinuteH = 0; // Modifified Hours
int Hour = 0; // Time

void setup(){for(int Pin = 0; Pin <= 14; Pin++){pinMode(Pin, OUTPUT);}}

void loop(){

Second = Second + 1;

if(Second == 60){
Minute = Minute + 1;
MinuteH = MinuteH +1;
Second = 0;
}
if(Minute == 60){
Minute = 0;
}
if(MinuteH == 12){
Hour = Hour + 1;
}
if(Hour == 60){
Hour = 0;
}


for(int A = 0; A <= 2; A++){
if(A == 0){Second = F;}
if(A == 1){Minute = F;}
if(A == 2){Hour = F;}


B = F/10;

if(B <= 3){
B = B + 9;
C = 13;
}else{
B = B + 6;
C = 14;
}

D = F-H;

if(D <= 4){
D = D + 3;
E = 8;
}else{
D = D - 2;
E = 9;
}

digitalWrite(A, HIGH);
digitalWrite(B, HIGH);
digitalWrite(C, HIGH);
digitalWrite(D, HIGH);
digitalWrite(E, HIGH);


}
}

There is still some bits missing such as making "A, B, C, D & E" low again and the actual timing (I assume ending the loop with "Delay(1000)" won't keep good time?).

 

[eSCHEn]

Good refactor mate

Have a look at these keywords and syntax, they'll make your life easier - switch cases and unary operators. Not that they will change the meaning of your code, more that it will make it cleaner for the next human to read it.

 

[Henrik]

The problem is similar to driving a bunch of 7 segment displays.

You can divide the circuit up into 8 leds, an drive the "banks" through something like a serial to parallel interface. Example code here https://www.arduino.cc/en/Tutorial/ShiftOut

There should be enough pins on an uno to just use the drivers directly connected, otherwise you can stack them (not the same ic, but something sinilar will be available)


It's a brilliant idea btw, might make one myself finally have a use for my rotary table

 

[Maker]

The problem is similar to driving a bunch of 7 segment displays.

You can divide the circuit up into 8 leds, an drive the "banks" through something like a serial to parallel interface. Example code here https://www.arduino.cc/en/Tutorial/ShiftOut

There should be enough pins on an uno to just use the drivers directly connected, otherwise you can stack them (not the same ic, but something sinilar will be available)


It's a brilliant idea btw, might make one myself finally have a use for my rotary table

I've read that tutorial a few times but I just can't get my head around it. I might just buy some shift registers to have a play with, maybe then I'll understand it.

 

[wookie]

I have a truly ancient book on "advanced digital electronics" from many many many years ago, most advanced thing is a transistor, would be fun/infuriating (delete as applicable) to make it from discrete components

Not discrete components but designing and building your own computer from discrete logic chips....http://www.homebrewcpu.com/overview.htm around 200 chips, 4000+ wires all done by hand, mad but impressive.

 

[Kayos]

Not discrete components but designing and building your own computer from discrete logic chips....http://www.homebrewcpu.com/overview.htm around 200 chips, 4000+ wires all done by hand, mad but impressive.

That's very impressive, I was thinking of reducing the problem to nand gates then making lots of 2 transistor nand gates and joining them together

 

[eSCHEn]

A work of art, chap is very skilled indeed.

I'd always fancied putting together some switch banks to illustrate binary storage and manipulation for students when I was teaching at Uni. Really really basic setup with light switches. Trouble was no one was interested in learning, just wanted spooning the answers

 

[Maker]

I have a truly ancient book on "advanced digital electronics" from many many many years ago, most advanced thing is a transistor, would be fun/infuriating (delete as applicable) to make it from discrete components

I think I've worked out how to make it from transistors, it's going to use about 2000, maybe more.

I am not considering it!

Well, maybe just a little bit.

 

[eSCHEn]

I think I've worked out how to make it from transistors, it's going to use about 2000, maybe more.

I am not considering it!

Well, maybe just a little bit.

If you used one of the larger smd profiles you wouldn't even have to drill holes...