Sign in Subscribe

Berlin Clock

Aidan Tim (maozzz)

• 3 min read

The Berlin Clock, also known as the 'Mengenlehreuhr,' displays time with a series of coloured flashing lights.

This clock works in base 5: www.3quarks.com/en/BerlinClock/index.html

I printed an acrylic board for the lights, which were WS2812 (aka Neopixel strips).

At first I wanted to solder individual lights, to fit to the acrylic board.

Soldering individual lights

However, this was time-consuming so I switched to using standard size lights and scale the board to the standard size. When I was done, I wired up all 4 rows of lights and the LED circle to the acrylic board.

Wiring and attaching lights to acrylic board

The Neopixel strips were coded:

#import
import time
from neopixel import Neopixel

rtc = machine.RTC()

YELLOW = (255, 255, 0)
RED = (0, 255, 0)
BLACK = (0, 0, 0)

secSMID = 0
minSMID = 1
hrSMID = 2

hrRow1NumBlocks = 4  #constant
hrRow1NumLightsInOneBlock = 3  #change this according to number of lights in one block
hrRow1NumLightsInAll = hrRow1NumLightsInOneBlock * hrRow1NumBlocks

hrRow2NumBlocks = 4  #constant
hrRow2NumLightsInOneBlock = 3  #change this according to number of lights in one block
hrRow2NumLightsInAll = hrRow2NumLightsInOneBlock * hrRow2NumBlocks

minRow1NumBlocks = 11  #constant
minRow1NumLightsInOneBlock = 1  #change this according to number of lights in one block
minRow1NumLightsInAll = minRow1NumLightsInOneBlock * minRow1NumBlocks

minRow2NumBlocks = 4  #constant
minRow2NumLightsInOneBlock = 3  #change this according to number of lights in one block
minRow2NumLightsInAll = minRow2NumLightsInOneBlock * minRow2NumBlocks

secRowNumLightsInAll = 8  #change this according to number of lights


#seconds of current time
def show_second(secs):
    pixelssec = Neopixel(secRowNumLightsInAll, secSMID, 1, "GRB")
    pixelssec.brightness(50)
    if secs % 2 == 1:
        pixelssec.set_pixel_line(0, secRowNumLightsInAll - 1, YELLOW)
    else:
        pixelssec.set_pixel_line(0, secRowNumLightsInAll - 1, BLACK)
    pixelssec.show()


#the hour of current time (needs to be in same loop because they share 1 state machine)
def show_hour(hr):

    #first hours row
    hrRow1NumBlocksLit = hr // 5
    hrRow1NumLightsLit = hrRow1NumBlocksLit * hrRow1NumLightsInOneBlock

    pixelshr1 = Neopixel(hrRow1NumLightsInAll, hrSMID, 9, "GRB")
    pixelshr1.brightness(40)

    #all the blocks that need to be lit
    for iBlock in range(hrRow1NumBlocksLit):
        for iLight in range(
                hrRow1NumLightsInOneBlock):  #for each light in the block:
            if iLight < hrRow1NumLightsInOneBlock:
                pixelshr1.set_pixel(iLight, RED)  #make it red
            else:  #the last light of each block is not used
                pixelshr1.set_pixel(iLight, BLACK)  #make it black

    #the rest of the blocks
    pixelshr1.set_pixel_line(hrRow1NumLightsLit, hrRow1NumLightsInAll - 1,
                             BLACK)
    pixelshr1.show()

    #second hours row
    hrRow2NumBlocksLit = hr % 5
    hrRow2NumLightsLit = hrRow2NumBlocksLit * hrRow2NumLightsInOneBlock

    pixelshr2 = Neopixel(hrRow2NumLightsInAll, hrSMID, 13, "GRB")
    pixelshr2.brightness(40)

    #all the blocks that need to be lit
    for iBlock in range(hrRow2NumBlocksLit):
        for iLight in range(
                hrRow2NumLightsInOneBlock):  #for each light in the block:
            if iLight < hrRow2NumLightsInOneBlock:
                pixelshr2.set_pixel(iLight, RED)  #make it red
            else:  #the last light of each block is not used
                pixelshr2.set_pixel(iLight, BLACK)  #make it black
    #the rest of the blocks
    pixelshr2.set_pixel_line(hrRow2NumLightsLit, hrRow2NumLightsInAll - 1,
                             BLACK)

    pixelshr2.show()


#the minutes of current time
def show_minute(mins):

    #first min row
    minRow1NumBlocksLit = mins // 5
    minRow1NumLightsLit = minRow1NumBlocksLit * minRow1NumLightsInOneBlock

    pixelsmin1 = Neopixel(minRow1NumLightsInAll, minSMID, 18, "GRB")
    pixelsmin1.brightness(40)

    for i in range(minRow1NumBlocksLit):
        firstLight = i * minRow1NumLightsInOneBlock
        lastLight = firstLight + minRow1NumLightsInOneBlock - 1
        #if block number is divisible by 3 (15, 30, 45 mins)
        if (i + 1) % 3 == 0:
            pixelsmin1.set_pixel_line(firstLight, lastLight, RED)  #make it red
        else:
            pixelsmin1.set_pixel_line(firstLight, lastLight,
                                      YELLOW)  #make it yellow

    pixelsmin1.set_pixel_line(minRow1NumLightsLit, minRow1NumLightsInAll - 1,
                              BLACK)
    pixelsmin1.show()

    #second hours row
    minRow2NumBlocksLit = mins % 5
    minRow2NumLightsLit = minRow2NumBlocksLit * minRow2NumLightsInOneBlock

    pixelsmin2 = Neopixel(minRow2NumLightsInAll, minSMID, 13, "GRB")
    pixelsmin2.brightness(40)

    #all the blocks that need to be lit
    for iBlock in range(minRow2NumBlocksLit):
        for iLight in range(
                minRow2NumLightsInOneBlock):  #for each light in the block:
            if iLight < minRow2NumLightsInOneBlock:
                pixelsmin2.set_pixel(iLight, YELLOW)  #make it yellow
            else:  #the last light of each block is not used
                pixelsmin2.set_pixel(iLight, BLACK)  #make it black

    #the rest of the blocks
    pixelsmin2.set_pixel_line(minRow2NumLightsLit, minRow2NumLightsInAll - 1,
                              BLACK)

    pixelsmin2.show()


while True:
    timestamp = rtc.datetime()
    _, _, _, _, hrs, mins, secs, _ = timestamp
    show_second(secs)
    show_hour(hrs)
    show_minute(mins)
    print(f"The time now is {hrs}:{mins}:{secs}")
    time.sleep(0.99)
My code

And after about 2 months of grueling wiring, lighting, and coding:

0:00
/
Finally!

Sign up for more like this.

Enter your email
Subscribe