INTRODUCING THE

SPACE CLOCK

ALWAYS RIGHT. AUTOMAGICALLY.

What is the SPACE CLOCK ?

The SPACE CLOCK sets itself using GPS signals to achieve microsecond accuracy of up to one millionth of a second. Not only is the SPACE CLOCK a physical clock, but it also acts as an NTP server (network time server) allowing you to sync precise time across all of your network devices.

SPACE CLOCK photo

Features

Captures `PPS (Pulse Per Second)` signal from `GPS satellites` which marks the exact start of a second
Parses `GPS NEMA` sentences which contain data including `UTC Time`, Latitude / Longitude and more
Built-in `NTP Server` for syncing network time
`Web interface` with status page and configuration options (24-hour Format, Timezone, Daylight Savings)
WiFi AP mode broadcasts a `hotspot` with web interface to `connect to nearby WiFi` networks
Open-source firmware, schematics, and space-age 3D printable case

Firmware

Firmware written in MicroPython includes logic for GPS, Clock, Web interface, NTP server and more.

[https://github.com/koga73/space-clock](https://github.com/koga73/space-clock)

Bill of Materials

SPACE CLOCK bill of materials

Optional for GPS

GPS antenna for housing internally
ML1220 li-ion battery for preserving ephemeris information and hot starts

Modes

The SPACE CLOCK can operate in modes with or without a WiFi connection.

No WiFi

First boot and when no WiFi credentials are present will simply show the current time.

Power via USB-C, will display `----`
GPS to process UTC time, will display `rising / falling animation`

> To connect to WiFI hold the bottom button for 3 seconds to reboot into AP Mode

WiFi Mode

If WiFi credentials are available it will attempt to connect, start web/ntp servers and then display the current time.

> If WiFi fails to connect the device will reboot

Power via USB-C, will display `----`
Connect to saved wifi, will display `wave animation`
Successful WiFi connection will display `IP address` once
Start servers for web interface and ntp
GPS to process UTC time, will display `rising / falling animation`

> You can view the status page when connected via WiFi Mode

SPACE CLOCK screenshot status

AP Mode

Power via USB-C, will display `----`
Scan for nearby networks, will display `SCAN`
Start the AP hotspot, will display the hotspot name and start the web server
You connect to the hotspot (`space_clock`)
You navigate to the default gateway (http://192.168.4.1)
A webpage will load showing nearby WiFi networks
You select a WiFi network and enter its password
Device will reboot into WiFi Mode

> You can view the connect to wifi page when connected via AP Mode

SPACE CLOCK screenshot connect

Configuration

The SPACE CLOCK operates on UTC Time and uses the following localized defaults which can be changed:

24-hour format: False
Timezone: (GMT-05:00) America/New_York
Daylight Savings: US/CA

> You can change these settings through the configuration page when connected via WiFi Mode or AP Mode

SPACE CLOCK screenshot config

24-hour format

The SPACE CLOCK supports displaying localized time in either 12-hour AM/PM format or 24-hour GMT/Military format

Button to change hour format

To quickly change between 12-hour / 24-hour formats just press the bottom button once

Web interface to change hour format

You can change this setting and more through the web interface when connected via WiFi Mode or AP Mode.

Timezone

GPS satellites transmit time in UTC, as such you can change the localized timezone.

Web interface to change TZ

Timezone can be set through the following selections in the web interface:

(GMT-10:00) Pacific / Honolulu
(GMT-09:00) America / Anchorage
(GMT-08:00) America / Los_Angeles
(GMT-07:00) America / Denver
(GMT-06:00) America / Chicago
(GMT-05:00) America / New_York
(GMT-03:00) America / Sao_Paulo
(GMT+00:00) UTC / Europe / London
(GMT+01:00) Europe / Paris
(GMT+02:00) Africa / Cairo
(GMT+04:00) Asia / Dubai
(GMT+09:00) Asia / Tokyo
(GMT+10:00) Australia / Sydney
(GMT+12:00) Pacific / Auckland

Daylight savings

GPS satellites transmit time in UTC, as such you can apply Daylight Savings with regional rules.

Web interface to change DST

Daylight Savings rules can be applied through the following selections in the web interface:

United States / Canada
- Starts on second Sunday of March at 2am
- Ends on first Sunday of November at 2AM
United Kingdom / European Union
- Starts on last Sunday of March at 1AM
- Ends on last Sunday of October at 2AM
Australia
- Starts on first Sunday of October at 2am
- Ends on first Sunday of April at 3AM

Reboot

You can reboot the device by clicking the "Reboot" button in the web interface.

Reset

You can factory reset the device by clicking the "Reset" button in the web interface. This will delete your preferences and reset the device back to defaults.

Build your own!

This project can be built for around ~$50 at the time of writing

Schematic

SPACE CLOCK schematic

Enable PPS on the Waveshare L76K

For the most accurate time, there is a small modification needed to the Waveshare L76K board which enables a PPS (Pulse Per Second) signal interrupt on `Pin 16`.

Follow the directions included in Waveshare's documentation, but essentially on the back of the board you just need to solder a `0O ohm resistor` or wire across the pads for `R20`.

Raspberry Pi Pico 2 W

The firmware is written in MicroPython, as such you will need to follow the instructions on flashing the MicroPython runtime.

Then follow the guide to Install dependencies and official VSCode extension

To upload the code to the Pico through VSCode just open the command palette (CTRL + SHIFT + P) and select `MicroPico: Upload project to Pico`

Power via USB-C breakout board

I wanted the ability to power the Pico via a USB-C breakout board and it was easy enough. Just connect the VBUS/VCC + GND on the breakout board to VSYS on the Pico `Pin 39` and GND to `Pin 38`

> You should put a Schottky Diode between external power and VSYS to prevent issues if powered via Micro-USB and Externally at the same time

Display

Since this is a clock, the good ole 4-digit 7-segment display makes sense!

Wiring:

Display GND to Pico GND `Pin 8`
Display VCC to Pico 3v3(OUT) `Pin 36`
Display DIO to Pico I2C0 SDA `Pin 6`
Display CLK to Pico I2C0 SCL `Pin 7`

> On my solderable breadboard I connected row 36 with row 5. On the female header I removed the pin on row 5. This allows for the 3V3(OUT) to be next to the other pins 6/7/8 needed for display.

Button

The button on the bottom allows for short presses such as to change between 12-hour / 24-hour format as well as long holds to toggle reboot of modes WiFi / AP

One leg of the button should go to GND `Pin 13` / `Pin 28` and the other leg should attach to GP20 `Pin 26`

3D printed case

SPACE CLOCK 3d printed case

The case consists of three parts, the display mount, the bottom plate and the top cover.

Print in PLA with or without infill.
Print top cover vertically with support

Use the appropriate M2/M3 screws listed in the bill-of-materials to mount the boards to the respective case pieces.

SMA connector

Inside the case cover is a pre-formed 0.25in cutout for an SMA connector if you want an external GPS antenna just can drill this out with a 0.25in forstner drill bit.

If you do not want an external GPS antenna you can place a small ceramic GPS antenna internally. I stuck mine to the backside of the female headers with 3M VHB tape.

Assembly

SPACE CLOCK inner back

Solder connections on the mini solderable breadboard as specified. Connect the USB-C breakout board and Display as specified. Plug the Waveshare L76K into the solderable breadboard female headers and then the Pico into the Waveshare female headers

Post your build!

If you make your own I would love to see it, post as a make or remix!

SPACE CLOCK inner front

Future plans

Automatically select Timezone and Daylight Savings via Latitude / Longitude coordinates
- Challenges with testing point in polygon timezone / region / country / state with resolutional accuracy and data size limits

Thingiverse x Raspberry Pi

This is my entry for the #PicoBuilders challenge hosted by Thingiverse in collaboration with the Rasperry Pi Foundation

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