Flip-Clock

The Flip-Clock is an old stylish, classic alarm clock with up to date features, such as automatic time adjustment, weather forecast, FM radio or Spotify playback. The device consists of three 3D printed flip digits, a PCB with integrated drivers for the digit controlling stepper motors and a Raspberry Pi 3 A+ with 3W speakers to run the main code.

All the mechanics and electronics are mounted within an 3D printed elegant cover. Additionally, a snoozer bar, two rotary encoders and a RGBW LED strip are included for the user interface.

Find additional info about each design in:

• 3D parts
• PCB hardware
• PCB firmware
• RPi3 software

Parts

3D printed flip digits

Each flip digit consists of a support structure with two bearings. The axle is placed inside the bearings holding two flap holders. All the flaps are mounted within those holders. The movement of the digit is achieved with a stepper motor and two gears. An IR transmitter and an IR receiver are palced on the top and on the bottom of the flaps to detect transitions. Additionally, a limit switch is placed close to the gears to synchronize with it each turn.

Subparts

1. Support structure
2. Bearings (623-2RS)
3. Axle
4. Flap holders
5. Flaps
6. Gears
7. Stepper motor (28BYJ-48)
8. IR transmitter (IR diode)
9. IR receiver (IR photodiode)
10. Limit switch (CLW1093)

FlipDigitController PCB

The FlipDigitController PCB includes a microcontroller and drivers to control the stepper motors. Additionally, the PCB also handles the IR transmitter and receiver to detect flap transitions and the limit switch for automatic synchronization of the axle. The PCB has an UART interface for the abstraction layer protocol.

The current version of the PCB can handle up to two flip digits at the same time. For the FlipClock device two units of the PCB have been used: one to control hours and minutes flaps, and another one to control weather flaps.

Block diagram	Layout

Subparts

1. MSP430FR2433 MCU
2. INA333 comparators
3. ULN2003A drivers

3D printed cover

Subparts

1. 3D printed top cover
2. 3D printed bottom cover
3. 3D printed front cover
4. 3D printed back cover

Rotary encoders

For the user interface two rotary encoders have been used. The used encoders can detect steps in both directions, and include a built-in switch. One of the encoders is used to control the volume (up/down/mute), whereas the other encoder controls the audio device (FM Radio/Spotify/OFF)

Wheels	Encoders

Subparts

1. 3D printed volume wheel
2. 3D printed control wheel
3. TT EN11-HSM1AF15 Rotary Encoders

Snooze bar

A snooze bar is included on top of the FlipClock device. This bar can be used to trigger the nightlight by default, or to stop/snooze the alarm when it has been triggered. Tactile switches are placed under the bar to detect when it is pressed.

Bar	Switch

Subparts

1. 3D printed snooze bar
2. EVQ-Q2S03W tactile switches

NeoPixel RGBW Stick

Two NeoPixel RGBW LED sticks have been included in the front of the FlipClock in order to provide nightlight and light-sign functions to the device.

Subparts

1. NeoPixel RGBW Stick

3W Speakers

Subparts

1. Stereo Enclosed Speaker Set - 3W 4 Ohm

FM radio tunner (RTL-SDR)

RTL-SDR dongle	FM antenna

Subparts

1. RTL-SDR dongle
2. FM antenna

Raspberry Pi 3 A+

Raspberry Pi 3 Model A+	Adafruit I2S 3W Stereo Speaker Bonnet

Subparts

1. RPI3 A+
2. Adafruit I2S 3W Stereo Speaker Bonnet

Power Supply

Power Supply Module	PSM Housing

Subparts

1. PS-05-5 power supply module
2. 3D printed housing

Wiring

The correct wiring to connect the different electronics is as follows:

PSM connection:

Subpart	PIN	PIN	Subpart
RPI3	5V	5V	PSM
RPI3	GND	GND	PSM

NeoPixel connection:

Subpart	PIN	PIN	Subpart
NeoPixel	DIN	MOSI	RPI3
NeoPixel	5VDC	5V	RPI3
NeoPixel	GND	GND	RPI3

Snooze Bar connection:

Subpart	PIN	PIN	Subpart
Snooze Bar	SW0	GPIO 4	RPI3
Snooze Bar	SW1	GPIO 17	RPI3

Volume Encoder¹ connection:

Subpart	PIN	PIN	Subpart
Volume Encoder	SW0	GPIO 24	RPI3
Volume Encoder	SW1	GPIO 25	RPI3
Volume Encoder	ROT0	GPIO 27	RPI3
Volume Encoder	ROT1	GPIO 23	RPI3
Volume Encoder	GND	GPIO 22	RPI3

Control Encoder¹ connection:

Subpart	PIN	PIN	Subpart
Control Encoder	SW0	GPIO 5	RPI3
Control Encoder	SW1	GPIO 6	RPI3
Control Encoder	ROT0	GPIO 12	RPI3
Control Encoder	ROT1	GPIO 16	RPI3
Control Encoder	GND	GPIO 13	RPI3

Flip-Clock-Controller PCB:

Subpart	PIN	PIN	Subpart
RPI3	3.3V	3.3V	Flip-Clock-Controller PCB 1 (HHMM)
RPI3	3.3V	3.3V	Flip-Clock-Controller PCB 2 (WW)
RPI3	TX	RX	Flip-Clock-Controller PCB 1 (HHMM)
Flip-Clock-Controller PCB 1 (HHMM)	TX	RX	Flip-Clock-Controller PCB 2 (WW)
Flip-Clock-Controller PCB 2 (WW)	TX	RX	RPI3

1: For ease of connectivity, all pins of rotary encoders are routed to GPIOs. These GPIOs will be configured as required with pull resistors or fixed voltages via software.