Introduction: Big, Auto Dim, Room Clock (using Arduino and WS2811)

Picture of Big, Auto Dim, Room Clock (using Arduino and WS2811)

First Hello instructables.

This is my first contact with :

  • Instructables
  • Arduino
  • Programmable LED's

So please don't trow rocks at me for noobish mistakes.

Keeping that in mind I'm waiting to read your comments with grate interest and I'm open to any suggestion

Features :

  • big digits ( each digit is approximately the size of a A4 paper).
  • slim in order to fit in a photo frame (a big one).
  • auto dim the light depending on the light in the room.
  • dedicated DST button.

Step 1: Prerequisites

Picture of Prerequisites

Things I used for this project :

Electronics :

  1. Arduino nano V3.0 (sadly since I can't afford an original arduino I used a chinese clone, for showing my support I donated 2.9 $ to arduino) - 2.9$ on ebay
  2. Digital Light Intensity Sensor Module Photo Resistor for Arduino - 0.99$ on ebay

  3. DS3231 AT24C32 IIC Module Precision Real Time Clock Quare Memory for Arduino - 0.99$ on ebay

  4. DC-DC Buck Converter Step Down Module LM2596 Power Output 1.23V-30V - 0.90$ on ebay

  5. 4m WS2811 led strip 30 leds/m - 12 $ on aliexpress (1 WS2811 IC control 3 LED Chip)

Total cost of electronics : 17.78 $ (without arduino donation)

Miscellaneous :

  1. Heat Shrink Tubing - 7.99$ ebay (assortment, it total 33m)

  2. 20 pcs 5 x 7 cm prototype pcb - 3$ ebay

  3. 3 pcs Micro Switch - 1$ locally bought

  4. Solder - 1$ locally bought

  5. Flux - 1$ locally bought
  6. UTP cable (individual wires used for various connections)
  7. LCD font ( - free
  8. Cardboard - free loacal supermarket
  9. Polystyrene board - 1.50$ locally bought

Various tools.

Step 2: Preparing - Digit Template

Picture of Preparing - Digit Template
  1. download and install LCD font (
  2. open word or similar editor and make a template similar to the image (first img)
    • font size ~800,
    • white font color black outline,
    • gray boxes where led strip fits
  3. Print and cut the gray strips with a exacto knife (second img)

Step 3: Preparing - Cut Cardboard and Led Strip

Picture of Preparing - Cut Cardboard and Led Strip

Using the digit template cut the cardboard to size (don't forget to leave space for the dots between hours and minutes)

If your LED strips came with connectors at each end (like mine did) desolder the connector and cut them in sets of 3.

Step 4: Stick the LED Strips

Picture of Stick the LED Strips

Using the template stick the LED strip on the cardboard.

It's not mandatory but I used a pencil to mark where the LED strips should be placed, this way I got to see the final form before attaching the LED's. It was a good thing since this is how I noticed I left two much space for those dots in the middle, as a result I had stuck the LED strips a little closer.

Step 5: Solder LED Strips

Picture of Solder LED Strips

Now starts a long soldering session.

Solder the LED strips in order to form a continues strip.

Notice the order in which to solder the strips in the picture.

For the middle dots I used a single LED strip and covered the middle LED with duct tape.

I used the following color code

  • Blue for ground
  • Green for data
  • Red for Vcc (12v)

Step 6: Wire Arduino on Breadbord

Picture of Wire Arduino on Breadbord

I tried doing a sketch in fritzing but I can't find all the parts :( , Sorry

So here is a list with all the connections and another picture with the setup on a breadboard

Step 7: Test LED's

Picture of Test LED's

Before loading this sketch (for which I assume no credit) don't forget to add FastLED library.

If everything went OK the LED's should cycle trough colors. If you have any problems first check your soldered points.

Step 8: Program the Clock

After struggling a little I managed to get a working clock that covers all my needs. I'm sure there is room for improvement.

The code is very commented, if you have any questions please feel free to ask. Also if you have any suggestions, please do tell.

All debugging messages are commented as well.

In order to change the color used you must modify the variable at line 22 ( int ledColor = 0x0000FF; // Color used (in hex)). You can find a list of colors at the bottom of this page:

If you have problems downloading the code file from instructables here is a mirror :

Step 9: Make Digits Form Using Polystyrene

Picture of Make Digits Form Using Polystyrene

Cut each segment in the template printed at the beginning.
Form each digit in the polystyrene using a exacto knife (very hard) or a Hot Wire Cutter.

You can see how I made mine in the pictures.

If you don't have a guitar string you can use just about any thin STEEL wire.

In order to power the Hot Wire Cutter I used the 12v LED power supply.

Also there is a picture with a cut digit. (sorry I forgot to take pictures in the process).

Step 10: Glue Digits and Adding Diffuser

Picture of Glue Digits and Adding Diffuser

After cutting all 4 digits and the dots glue all of them on the cardboard with the LED strips. (for this process I used
double sided adhesive tape).

In order to diffuse the LED light I used 2 paper sheets on top of the polystyrene. For convenience and aesthetics I used a single A2 size paper folded in two.

Also for finishing touches I've put the entire assembly in a large picture frame.


ИгорьБ27 (author)2018-01-10

It does not load ... Here's the error.

Arduino: 1.8.5 (Windows 10), Плата:"Arduino Nano, ATmega328P"

In file included from C:\FLTK1MPIGJOSU6N\FLTK1MPIGJOSU6N.ino:1:0:

C:\Users\Игорь\Documents\Arduino\libraries\DS3232RTC-master/DS3232RTC.h:136:26: error: 'tmElements_t' has not been declared

static byte read(tmElements_t &tm);


C:\Users\Игорь\Documents\Arduino\libraries\DS3232RTC-master/DS3232RTC.h:137:20: error: 'tmElements_t' has not been declared

byte write(tmElements_t &tm);


In file included from C:\FLTK1MPIGJOSU6N\FLTK1MPIGJOSU6N.ino:4:0:

C:\Users\Игорь\Documents\Arduino\libraries\FastLED-master/FastLED.h:17:21: note: #pragma message: FastLED version 3.001.005

# pragma message "FastLED version 3.001.005"


C:\FLTK1MPIGJOSU6N\FLTK1MPIGJOSU6N.ino: In function 'int GetTime()':

FLTK1MPIGJOSU6N:34: error: 'tmElements_t' was not declared in this scope

tmElements_t Now;


FLTK1MPIGJOSU6N:35: error: 'Now' was not declared in this scope;


C:\FLTK1MPIGJOSU6N\FLTK1MPIGJOSU6N.ino: In function 'void TimeAdjust()':

FLTK1MPIGJOSU6N:138: error: 'tmElements_t' was not declared in this scope

tmElements_t Now;


FLTK1MPIGJOSU6N:139: error: 'Now' was not declared in this scope;


exit status 1

'tmElements_t' was not declared in this scope

ИгорьБ27 (author)2018-01-10

Hello. I ask you to help deal with the clock.

I have such a problem, the sketch does not load, a constant error, although others are loaded without problems. I downloaded all the libraries (like). I tried it on different versions, from arduino 1.6.0 to the latest. Please look and if you can help me.

snowy1998 (author)2017-12-30

Hey, somebody ripped off your 'ible

and he's also ripped off somebody else's sitway too.

RaimisS (author)2017-11-29

Hi everyone,

I have replicated this project with some additions. Here you will find my code:

I have added Dallas sensor for measuring outside temperatures. Positive temperature are working good but I am not success with negative temperatures. Might be someone can help me with this. I do not know how to light up minus and corectly diplay negative temperatures. Thanks

RaimisS (author)RaimisS2017-12-02

Already made working code. You can use it from github.

sayali kedar (author)2017-03-31

error code please help.

sketch_mar31a.ino:1:23: fatal error: DS3232RTC.h: No such file or directory

compilation terminated.

my gmail.

RaimisS (author)sayali kedar2017-11-21

you have not added library DS3232RTC.h

pmiller2 (author)2017-11-08

Very good project. Well done.

BenjaminR98 (author)2017-10-06

could someone pass me the code please

OvidiuB7 (author)2017-09-19

Hello everyone!!! Thank you for this awesome project! I already built, but I have a little problem... I conected D0 pin from light sensor to D3 arduino pin and no working, but when i connect D0 pin to A3 arduino pin it's working...

This is good or bad? can someone help me...


sayali kedar (author)2017-09-12

Sar plz add a HH:MM:SS code

wachinida (author)2017-08-27

Where is 5 x 7 cm prototype pcb was used ?

MartinL136 made it! (author)2016-05-02

Thanks for your instructable ;)

After i realized that i shorted the sdl and scl line it works like a charm.

I've found a bug in your arduino script.

You can't use integer for the ledcolor, you have to use longinteger. Else your unable to use the red color.

Also i added some lines to use different colors at different times of day.

regards Martin

darkpetter (author)MartinL1362017-08-23

amigo serias tan amable de pasarme el codigo de programacion!!! he armado la circuiteria pero no se cual de las que exponen sea la correcta,por lo que muestras considero que la suya es la correcta.

petter121 (author)MartinL1362017-08-20

amigo podrias pasar el codigo

MartinL136 made it! (author)MartinL1362016-05-02

Bug and addition

svenzy (author)MartinL1362016-05-03

can you post your code on github or directly here? I cant see well on those pictures.. thanks

abdelhadj made it! (author)2016-01-04

Thank you everyone, i made my 1st version based on WS2812B cut by 3.

I will finish it later, maybe try to print the Temperature or add some effects! so many possibilities with those Leds it's awesome!!

petter121 (author)abdelhadj2017-08-20

puedes pasarme el codigo amigo..hebuscado el codigo y nadie lo comparte!

FormUser (author)abdelhadj2017-03-07

tek renk şerit led kullanarak yapmak mümkün mü

termometre de ekleyebilir miyiz

onlynoise (author)abdelhadj2016-01-06

Nice work,

You can get the temperature form RTC module using this code

int t = RTC.temperature();
float celsius = t / 4.0;

float fahrenheit = celsius * 9.0 / 5.0 + 32.0;

You can comment the last line if you want celsius.

hi, im almost finished with this great project. I just dont understand how to put this temperature code into the full code. Im total noob to programming ;-) can u help ? thanks a lot

abdelhadj (author)onlynoise2016-01-06

Thanks for sharing this with us and thx for the tip i think you meant float t ;)

here is a video of what it looks like : every minute i add the cylon effet example and then it changes the color randomly from preselected array of colors.

Here is my code :

#include <DS3232RTC.h>
#include <Time.h>
#include <Wire.h>
#include <FastLED.h>

#define NUM_LEDS 90 // 5 by segment + 6 in the middle
#define LED_TYPE WS2812
#define COLOR_ORDER GRB // Define color order for your strip
#define BRIGHTNESS 150
#define LED_PIN 5 // Data pin for led comunication

CRGB leds[NUM_LEDS]; // Define LEDs strip

byte digits[10][21] = {
0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1 }
, // Digit 0
0,0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1 }
, // Digit 1
1,1,1,1,1,1,1,1,1,0,0,0,1,1,1,1,1,1,0,0,0 }
, // Digit 2
1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,1,1,1,1,1,1 }
, // Digit 3
1,1,1,1,1,1,0,0,0,1,1,1,0,0,0,0,0,0,1,1,1 }
, // Digit 4
1,1,1,0,0,0,1,1,1,1,1,1,0,0,0,1,1,1,1,1,1 }
, // Digit 5
1,1,1,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1 }
, // Digit 6
0,0,0,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,1,1,1 }
, // Digit 7
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1 }
, // Digit 8
1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,1,1,1,1,1,1 }
}; // Digit 9 | 2D Array for numbers on 7 segment

byte firstdigit[2][10] = {
0,0,0,0,0,0,0,0,0,0 }
, // Digit 0 first number

1,1,1,1,1,1,1,1,1,1 }
}; // Digit 1 first number | 2D Array for numbers on 7 segment

bool Dot = true; //Dot state

bool DST = false; //DST state
int last_digit = 0;
//long ledColor = CRGB::DarkOrchid; // Color used (in hex)
long ledColor = CRGB::MediumVioletRed;
long ColorTable[16] = {
void setup(){


FastLED.addLeds<WS2812B, LED_PIN, RGB>(leds, NUM_LEDS);
// FastLED.addLeds<LED_TYPE, LED_PIN, COLOR_ORDER>(leds, NUM_LEDS).setCorrection( TypicalLEDStrip );
FastLED.setBrightness( BRIGHTNESS );
pinMode(2, INPUT_PULLUP); // Define DST adjust button pin
pinMode(4, INPUT_PULLUP); // Define Minutes adjust button pin
// pinMode(5, INPUT_PULLUP); // Define Hours adjust button pin


// Check Light sensor and set brightness accordingly
void BrightnessCheck(){
const byte sensorPin = 3; // light sensor pin
const byte brightnessLow = 75; // Low brightness value
const byte brightnessHigh = 100; // High brightness value
int sensorValue = digitalRead(sensorPin); // Read sensor
if (sensorValue == 0) {
Serial.println("Brightness High");

else {
Serial.println("Brightness Low");


// Get time in a single number
int GetTime(){
tmElements_t Now;;
//time_t Now = RTC.Now();// Getting the current Time and storing it into a DateTime object
int hour=Now.Hour;
int minutes=Now.Minute;
int second =Now.Second;
if (second % 2==0) {
Dot = false;
else {
Dot = true;
return (hour*100+minutes);

void DSTcheck(){

int buttonDST = digitalRead(2);

Serial.print("DST is: ");

if (buttonDST == LOW){

if (DST){


Serial.print("Switching DST to: ");


else if (!DST){


Serial.print("Switching DST to: ");





// Convert time to array needet for display

void TimeToArray(){

int Now = GetTime(); // Get time

int cursor = 90; //116

Serial.print("Time is: ");

if (Dot){

else {



for(int i=1;i<=4;i++){

int digit = Now % 10; // get last digit in time

if (i==1){

cursor =69; //82

Serial.print("Digit 4 is : ");
Serial.print(", the array is : ");

for(int k=0; k<=20;k++){


if (digits[digit][k]== 1){

else if (digits[digit][k]==0){

cursor ++;

}; // fin for

if (digit != last_digit)
{ fadefonction();
ledColor = ColorTable[random(16)];
last_digit = digit;

}// fin if

else if (i==2){

cursor =48;

Serial.print("Digit 3 is : ");
Serial.print(", the array is : ");

for(int k=0; k<=20;k++){


if (digits[digit][k]== 1){

else if (digits[digit][k]==0){

cursor ++;




else if (i==3){

cursor =21;

Serial.print("Digit 2 is : ");
Serial.print(", the array is : ");

for(int k=0; k<=20;k++){


if (digits[digit][k]== 1){

else if (digits[digit][k]==0){

cursor ++;




else if (i==4){

cursor =0;

Serial.print("Digit 1 is : ");
Serial.print(", the array is : ");

for(int k=0; k<=20;k++){
if (digits[digit][k]== 1){
else if (digits[digit][k]==0){
cursor ++;
// Serial.println();

Now /= 10;
void TimeAdjust(){
int buttonH = digitalRead(5);
int buttonM = digitalRead(4);
if (buttonH == LOW || buttonM == LOW){
tmElements_t Now;;
int hour=Now.Hour;
int minutes=Now.Minute;
if (buttonH == LOW){
if (Now.Hour== 24){
else {
Now.Hour += 1;
else {
if (Now.Minute== 59){
else {
Now.Minute += 1;

void fadeall() {
for(int m = 0; m < NUM_LEDS; m++) {

void fadefonction () {
static uint8_t hue = 0;
// First slide the led in one direction
for(int i = 0; i < NUM_LEDS; i++) {
// Set the i'th led to red
leds[i] = CHSV(hue++, 255, 255);
// Show the leds;
// now that we've shown the leds, reset the i'th led to black
// leds[i] = CRGB::Black;
// Wait a little bit before we loop around and do it again

// Now go in the other direction.
for(int i = (NUM_LEDS)-1; i >= 0; i--) {
// Set the i'th led to red
leds[i] = CHSV(hue++, 255, 255);
// Show the leds;
// now that we've shown the leds, reset the i'th led to black
// leds[i] = CRGB::Black;
// Wait a little bit before we loop around and do it again
void loop() // Main loop
/*BrightnessCheck(); // Check brightness
DSTcheck(); // Check DST
TimeAdjust(); // Check to se if time is geting modified*/
TimeToArray(); // Get leds array with required configuration; // Display leds array

/*float t = RTC.temperature();
float celsius = t / 4.0;
Serial.print("Temp is : ");


FiliepV made it! (author)2017-08-17

Thx for this nice project. I made also a pcb for it. I'm totally new with Arduino. Can someone tell me how I can change the color on different times. For example: 8 am red, 10 am green, 10.15 am red 12 am green, 1 pm red, ... I used the clock.ino file of the site.

MariusB49 (author)2017-08-10

Hello!! Someone have the corect code for this project, cause i get some error from this code. In principle the 'tmElements_t' was not declared.

Can anybody give me a solution? Thanks.

AiGreek (author)2017-05-09

Did it a few weeks ago with 3 WS2812/segment and some 3D printing. Everything works but after some time, the clock just stop working (some lag at first then stucked)

quieliner (author)2017-04-01

hello, i interest with this project, but i use ws2812b for the segment, is anybody have a code, i try in saxos1983 github it's not available... i want 24 hours clock like onlynoise build.. thanks

sayali kedar made it! (author)2017-03-31


HalilC3 (author)2017-01-30

bu projenizi çok beğendim. bende yapmak istiyorum .kodlamada sorun yaşıyorum. program derlemede hata gösteriyor. bana projenizin detaylarını yollarmısınız. teşekkür ederim. iyi çalışmalar.

onlynoise (author)HalilC32017-01-30

In English please, I can't understand where you need help.

FormUser (author)onlynoise2017-03-07

with this product this project Can we work
We only want to use arduino and rtc in the circuit, and we want to show the time on the screen.
Could you help.

FormUser (author)HalilC32017-03-06

calisan kod var mi hocam sizde

FatmirH (author)2017-02-11

Hi there, this is a cool project. I have already built the clock, but i'm having a problem with the code. When i try to compile it i get the error

exit status 1

'tmElements_t' was not declared in this scope

I have already fastled and DS3232RTC libraries.

Any idea? Thanks.

FormUser (author)FatmirH2017-03-04

I am getting the same mistake, how did you solve

FatmirH (author)FormUser2017-03-04

I added


and the problem was solved .

FormUser (author)FatmirH2017-03-07

Http: // ...

tek renk şerit led kullanarak bu projeyi yapabilir miyiz

bu kodlar ile çalışır mı

albeagle (author)FormUser2017-03-04

I had to add


FatmirH (author)FatmirH2017-02-11

Problem solved :). I had to add

#include <TimeLib.h>

Thankyou :)

ГеннадийБ2 made it! (author)2016-07-27

Cool project! He decided to build this same! ( Few had to rewrite the code, I have a number of LEDs in segments - more! It wanted to make it shows the date and temperature! I already have DHT11 module! Unfortunately, I do not know how to program the Arduino.

projeniz calisir durumda mi
kod ve devre semasini paylasir misiniz

hirez66 made it! (author)2016-05-08

I have made the same project, it is gr8 weekend project

FormUser (author)hirez662017-03-06

yaptiginiz projeye ait devre semasi ve kodlari paylasir misiniz.
than you

joemxwolf (author)hirez662016-10-31

good day sir! can i ask how you code this clock? i want to have a countdown timer similar to this display. can you help me how to program it? only 24 seconds for a shot clock. thanks.

Hello Friend! I also plan to assemble LED ws2812b, but none like can`t find a suitable sketch. Could you share your sketch?

AntonySoprano (author)hirez662016-06-02

Hello friend. share the sketch, too, wanta thermometer

kraiv (author)2017-02-26

Thank you. I did on the 2812b, 2 pieces per segment. The hardest part was cut out pattern ... and it's not a joke, too small partitions in numbers. Thanks again.

RandyK50 (author)2017-02-24

hey how do i add the temperature on the 7 digit display ?

i made the clock with the ws2811 led's.

PunkyB (author)2017-02-17

Great build! I want build it but i want to edit a little. I want to make a stopwatch that can count until 99,99 seconds, please can you answer me to some questions ?

1. What more parts i need to make it work?

2. Can I add 3 buttons, Start,Stop and reset?

3 Can i use two stopwatches on one Arduino board and have there 4 buttons,Start, Stop 1, Stop 2 and reset?

Thank you in advantage

ps:I don't know nothing about Arduino, I am learning it now and i like it :)

BryanM125 (author)2016-12-25

ayuda me brindarías los archivos no soy premiun

metro es

muchas gracias

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