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Single digit Nixie clock

(Can drive any other display from the BCD output)

User guide V1.0

MCU based single digit clock with loads of « intuitive » functions:


·       Display time flashing digits one after another

·       12Hr or 24Hr time display

·       HH:MM or HH:MM:SS

·       DD/MM/YY or MM/DD/YY date format

·       automatic calendar  (leap year calculation)

·       Fade-in display or straight display

·       Software controlled luminosity, can be adjusted globally and hour per hour (smooth steps from very low to maximum)

·       Seconds beat output (to drive LED, Neon lamp or Nixie dot)

·       Bottom LED tube high-lighting software controlled

·       Precision setting (allows zero second easy precision setting)

·       Alarm with auto repeat & snooze functions

·       Chimes (programmable)

·       Vacation mode (time on demand mode, keep the HV turned off until the button is pressed to display the time)

·       User programmable “sleep” hours with loads of options for each hour

a.    specific dim display (from 0 to 100%)

b.    chime (yes/no)

c.     tube on/off (when off, time will be displayed when button pressed)

d.    LED on/off

·       CPU controlled dynamic duty high voltage generation for Nixie tubes



Easy single button entry for all functions:


A short press of the button gives:


·       during normal display.è will display the date

·       during alarm . . . . .è    will activate the snooze function

·       during vacation mode .è will display the time


A long press of the button gives:


·       during normal display or display off. è will enter the menu*

·       during alarm .  .  .  .  .  .  .  . . è will shut alarm off (for the day only) (audible double “bip” confirmation)


*Enter the menu:


A long press on the button will enter the menu, releasing the button will select the displayed menu entry; menu entries are blinking digit display:


0       Displays alarm and allows on/off setting

1       Alarm set, (press the button when the desired digit shows-up, display is repeated after alarm has been set, and time can still be corrected during the repeated display)

2       Time set, (press the button when the desired digit shows-up, the new entry will repeat and the second indicator will start to blink very fast until you press again the button to set the 0’ second synchronization

3       Date set, (press the button when the desired digit shows-up, display is repeated after date has been set)

4       Sleep menu: (display in form “HH – s - 8” – HH=hour, s=status flag, 8=light calibration)




5                   Switch between 12H and 24H format

6                   Switch date format between DD/MM/YY AND MM/DD/YY

7                   Switch display format between HH:MM AND HH:MM:SS

8                   Switch between vacation mode (time on demand) and normal operation mode

9                   Select the calibration sub menu (displayed at high rate blink)



MPU Pin description

Version 1 rev 0 - Patrick Mignot 2009