Assembly and tests

All parts are listed here.


Prepare the housing

  • Unscrew cover and hinges.
  • Remove the two skirting boards by carefully bending them back and forth with pliers. Make sure that the side walls are not damaged.
  • Drill holes
    • for the speaker: in the middle of the rear wall
    • for the volume potentiometer: at the level of the alarm rotary switch
    • for the (USB) cable entry: at the level of the alarm rotary switch
    • for the two drive-in nuts: in the middle of the side walls
  • Finish the hole for the volume potentiometer, taking into account the thread length of the potentiometer, using a flat countersink.
  • Insert drive-in nuts.
  • Cut out the wooden floor; leave 10 mm at the left edge (front view); 20 mm at the other edges; here too take care not to damage the side walls.


Prepare the lower front panel and connect it to the housing

  • 8 Drill holes for M4 countersunk screws for fixing to the bottom of the wooden box in the upper and lower edge.
  • Make sure that they lie approximately in the middle of the 20 mm edge of the floor.
  • Insert and screw the front panel.
  • The rotary switches and potentiometers have a "nose" to prevent their housing from rotating. If necessary, the lower front panel must be reworked and adapted accordingly.


Prepare and install the displays

  • Carefully drill the mounting holes of the backpack to Ø 2.5 mm.
  • Solder the displays into the backpack.
  • Provide the yellow display with a solder bridge over 'A0' so that it has the I2C address 0x71.
  • Solder the 5-pin connecting cables. See photos.
  • Lower the fixing holes in the lower front panel for the M2 countersunk screws.
  • Connect the displays to the front panel, making sure that the surface of the displays is flush with the surface of the lower front panel.


Prepare the RTC module

RTC module, button cell, pin strip
RTC module, button cell, pin strip
  • Solder on the pin strip.
  • Insert the button cell.


Prepare the DFPlayer module and SD card

DFPlayer and SD card
  • Rename an arbitrary MP3 file (song or sound you want to wake up with) so that it starts with "0001-" and ends with".mp3" (e.g. "0001-mein-song.mp3") and copy it to the root directory of a FAT32-formatted SD card.
  • Insert the card into the slot of the DFPlayer.


Prepare the FRAM module

FRAM module
  • Solder on the pin strip.


Prepare the controls

  • Solder 2-pin connection cables to the 8 buttons.
  • Solder one 2-pole connection cable to one of the two rotary switches. Pin assignment see photo.
  • Solder one 3-pole connection cable to the other rotary switch. Pin assignment see photo.
  • Solder 3-pin connection cables to the 3 rotary potentiometers. Pin assignment see photo.
  • Shorten the operating shafts of the potentiometers so far that the knobs fit on them at a suitable distance from the front panel and the wooden wall of the box.

Tip 1
Although the connecting cables can be soldered directly, it is easier to connect crimp sockets to the cables of the switches and potentiometers first, plug them onto the pins and then solder them.

Tip 2
To protect the connection electrically and to make it mechanically more robust you can use shrink tubing (here in the pictures: transparent).


Install speaker and volume control

Speaker, potentiometer
  • Insert the speaker.
  • Mount the volume potentiometer and attach the rotary knob.


Prepare the labeling sheet

Insert sheet on cutting mat
Insert sheet on cutting mat
  • Print out the label sheet on the thickest possible paper.
  • Cut off edges.
  • Cut out rectangles for displays.
  • Cut out holes for switches, potentiometers and buttons. Best on a cutting mat.


Attach the upper front panel and install the controls

Device with front panel, display and operating elements
  • Insert tinted foil to cover the displays together with the label sheet.
  • Insert the front panel.
  • Cut the holes for switches, potentiometers and buttons into the tinted foil.
  • Insert and fix switches, potentiometers and buttons.
  • Use the setting ring to limit the clock switch to two switching positions.


Prepare, install and wire the PCB

The board "ÜKO-WECKER-180318" differs from its predecessor "OHAC1802" (here in the picture) only by its width
The board "ÜKO-WECKER-180318" differs from its predecessor "OHAC1802" (here in the picture) only by its width
  • Solder components in this order
    • Resistors
    • 2- to 5-pole sockets
    • Header bars
    • Terminal blocks
    • Stacking strips (put PCB onto the Arduino Mega beforehand)
  • Screw PCB with distance sleeves to the front wall of the box (push-button side) in such a way that there is still enough space to the right for the small relay PCB
  • Plug in DFPlayer, FRAM and RTC DS3231
  • Connect according to the PCB marking or the wiring diagram (see Wiring)
    • 2- and 3-pole plugs of switches and buttons
    • 3-pin connectors of the potentiometers
    • 5-pin connectors of the displays


Install and connect the relay PCB

PCB and relay PCB
  • Screw the relay PCB to the right of the main PCB to the front wall
  • Connect one wire of the speaker to the relay PCB, the other to the terminal block on the main PCB.
  • Establish the remaining connections between the relay PCB and the main PCB (see Wiring)


Connect and secure the USB cable

  • Pass the USB cable through the back of the case and plug it into the Arduino
  • Attach the strain relief to the side panel


Download and install the libraries

Download and install the sketch and parameter set

  • Download the latest version of the sketch and parameter set here and save them to your Arduino sketchbook folder.
  • Connect the USB cable to the PC where the Arduino IDE is installed
  • Open the sketch
  • Select board type and COM port, if necessary
  • Upload Sketch


Test functions

  • Check whether
    • the brightness of the displays can be adjusted
    • the time and alarm time can be set
    • the alarm sound is played
    • the volume can be adjusted
    • the MP3 file can be played completely
    • the MP3 file can be interrupted by switching to "Alarm off" or "Alarm set"
    • the relay has only energized while the MP3 file is playing
  • After exiting the IDE, disconnecting the USB cable from the PC and connecting it to the Powerbank, check that
    • the time and alarm time after disconnecting the Powerbank from the power supply and disconnecting the USB cable from the Powerbank survive


Modify constants

  • The sketch contains the line:
    "#include "parameterset4clock3.h" // Parameters for Clock No. x"
    That is because I had built three Alarm clocks at that time. Please change it to:
    "#include "parameterset4clock1.h" // Parameters for Clock No. 1"
    You can then use the file parameterset4clock1.h to set some constants that can be used to adjust the behaviour of the displays, the DFPlayer and the minute keys of the alarm time.
    • Displays: The constants MIN_C and MAX_C are used to compensate for differences in brightness between the displays or to adjust the brightness according to one's own preferences. It can be used to set the lowest and highest brightness values for the time display. The same applies to MIN_A and MAX_A, which are responsible for the alarm display.
    • DFPlayer: MIN_V and MAX_V indicate the lowest and highest volume value. Values between 0 and 30 are allowed, the setting should depend on the type and volume of the MP3 file. The lower value should always be slightly higher than 0 so that the alarm cannot (accidentally) be set to silent. The upper value should not exceed the point at which the speaker might start to boom.
    • Minute keys of the alarm time: With MIN_STEP_WIDTH you can select the interval at which the minute keys increase or decrease the alarm time. It should be an integer divider of 60, i.e. 1, 2, 3, 4, 5, 6, 10, 12, 15, 20 or 30, default value is 1.


Wall mounting

  • Ideal mounting height: the user should stretch their arms slightly upwards in a supine position and lying on their usual cushion. This height is optimal for the bottom side, the control panel of the alarm clock. Fix the mounting plate to the wall using dowels and screws.

Cable duct, power supply and power bank

Cable duct, power bank, power supply unit
Cable duct, power bank, power supply unit
  • To lead the USB cable down or to the side, an optional cable duct (DIY store) can be used.
  • Place the power supply and power bank according to the space available and make sure that both remain completely free of any objects (bedspreads, plush toys, magazines, etc.) that could hinder their heat dissipation. Otherwise there is a fire hazard!