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Sup Sup Forums

Today I made a clock. I'm going to take it to school tomorrow to show off to all my classmates.

The brain is an Arduino Mega because I needed a lot of digital outputs.

Spaghetti monster stage.

ahmed please take your bomb elsewhere

>because I needed a lot of digital outputs.
Missed opportunity for multiplexing and really impress your classmates.

There's a RTC module, so it will keep time when unplugged. And temperature diode connected as well, that's what the bottom row of LEDs is displaying.

Cool clock. Want to come to the white house?

I wanted to but I couldn't figure out how to without adding another chip that I don't have.
All of the LEDs can act independently of each other so how would I divide them into channels?

Like pic related. In this case 25 LEDs driven from 10 pins. For other configs you can drive x*y LEDs with x+y pins. You will sacrifice some intensity but because of the non-linear properties of human sigh this will hardly be noticeable until you multiplex a shit load of LEDs.

If you use charlieplexing, you only need 6 for 25

Don't forget you'll still need a resistor for either every column or row.

Even cooler. OP, do this.

But what if I want LED 17 on at the same time as LED 8?

You switch between the LEDS very quickly.
So it will be "on" at the same time to the naked eyes.

That's true. I do have the transistors available for it.

I'll give it some thought.

If you are driving the LEDs directly from the Arduino now then you don't have to add transistors to multiplex, unless you want to increase the current to compensate for duty cycle. Also, if you must, use logic level FETs like the BS123 so you don't have to worry about base current or saturation voltage.

Can you give me more information about which college you go to so I can call the authorities?

You want that kid to visit the white house?

I hope to see some articles about this. Do not disappoint me.
What minority are you?

You really don't need an Arduino pro for that.... That's making a clock on easy mode. Go bare board. But good job on including an rtc.

I had it sitting around so it's not like I bought it especially for this.
In fact everything used was just sitting around.