NixieAccurateClock

nixie-clock-ice

Hardware and software source for a GPS nixie tube clock with delay correction.

Uses a PICO-iCE v3 FPGA + MCU module.

• Raspberry Pi RP2040 processor
• Lattice UltraPlus ICE40UP5K FPGA with 5.3k LUTs, 1Mb SPRAM, 120Kb DPRAM, 8 Multipliers

Building

Cloning

Clone with git CLI of the native OS (Windows if running WSL). This avoids checkout conflicts. Github desktop recursively inits submodules, which breaks on Windows due to path length limitations.

git clone https://github.com/willis936/nixie-clock-ice.git

Once cloned cd to software/lib and run these commands to initialize the submodules:

git -C pico-ice-sdk submodule update --init
git -C pico-sdk submodule update --init lib/tinyusb

Run these commands until the output stops changing. Running them once is likely not sufficient.

See the "Using the SDK" section of the pico iCE "Getting Started" page.

https://pico-ice.tinyvision.ai/md_getting_started.html

MCU

Follow the pico ice Getting Started section.

Using Ubuntu WSL the apt version of cmake is currently not high enough.

Install an appropriate version like this:

https://www.linuxcapable.com/how-to-install-cmake-on-ubuntu-linux/

sudo apt update && sudo apt install build-essential checkinstall zlib1g-dev libssl-dev g++ gdb make ninja-build rsync zip gcc-arm-none-eabi
cd /usr/local/src
sudo wget https://github.com/Kitware/CMake/archive/refs/tags/v3.28.1.tar.gz
sudo tar -zxvf v3.28.1.tar.gz
sudo rm v3.28.1.tar.gz
cd CMake-3.28.1
sudo ./bootstrap
sudo make
sudo make install

For MacOS with homebrew installed:

brew install cmake gcc-arm-embedded zlib gdb make rsync zip

FPGA

Make sure python 3.7+ is installed on WSL.

You may need to install pyenv, remove prior pip installations, and re-bootstrap.

https://gist.github.com/monkut/35c2ef098b871144b49f3f9979032cee

https://pip.pypa.io/en/stable/installation/

Install apio and oss CAD suite.

You may need to restart WSL in between the pip installation of the package and the package installation (last two commands).

sudo apt update && sudo apt install python3-pip yosys
pip install -U apio
apio install -a

For MacOS:

brew install yosys
pip3 install -U apio

Test project using the APIO guide here:

https://pico-ice.tinyvision.ai/md_programming_the_fpga.html

Use UF2 on WSL to convert the bin to UF2 then copy over CURRENT.UF2 on mounted USB drive pico ice.

https://github.com/tinyvision-ai-inc/uf2-utils/

cd /usr/local/src
sudo git clone https://github.com/tinyvision-ai-inc/uf2-utils.git
cd uf2-utils && sudo make install

Enclosure development

If you want to modify the FreeCAD FCStd files you should configure zippey (located in software/lib) with these commands from git bash (Windows) or shell (linux) with the repo as pwd:

git config filter.zippey.smudge "$PWD/software/lib/zippey.py d"
git config filter.zippey.clean "$PWD/software/lib/zippey.py e"

Note that you need python 3 installed and added to path as python for the .FCStd files to properly compress on clone.

The enclosure was developed in FreeCAD 0.21.2 + Assembly3. The Assembly3 plugin is needed to load the .FCStd file and modify the enclosure.

The enclosure starting point was generated by Protocase's template generator.

Requirements

1. Display the time with 1 microsecond accuracy.
2. Display the time with 1 second precision.
3. Use nixie tubes to display the time.
4. Do not require or allow the user to manually set the time.
5. Display the time within 30 seconds of power on.
6. Use a single power entry.
7. Use a single radio receiver to establish local timebase.
8. Have a user-selectable mode for Daylight Savings Time (DST) checking.
9. Use longitude to estimate DST date range.
10. Have a user-selectable mode to force DST offset on (off when both this and DST check mode are off).
11. Use longitude to estimate timezone.
12. Have a user-selectable timezone offset.
13. Be able to use software to control nixie tube brightness.
14. Use an ambient light detector to automatically adjust nixie tube brightness.
15. Have a user-selectable manual brightness mode.
16. Use a potentiometer to set the brightness in manual brightness mode.
17. Run a nixie tube anti-poisoning routine once a day (cycle through all digits at high brightness for a minute).
18. Have a user-selectable mode to enable daily anti-poisoning routine
19. Have a user-selectable mode to force anti-poisoning routine on indefinitely.
20. Have a user-selectable 12-hour / 24-hour display mode.
21. Use a nixie tube decimal point to indicate AM/PM in 12-hour display mode.
22. Use a nixie tube decimal point to indicate that the radio receiver is locked.