A digital clock with perpetual calendar, alarm, countdown timer/appliance timer, and day counter. Written for the Arduino Nano at the heart of RLB Designs' Universal Nixie Driver Board (UNDB) v5.0, featuring a DS3231 real-time clock, and driving up to 6 digits multiplexed in pairs via two SN74141 driver chips.
The latest release can be downloaded here. Skip to Hardware Configuration for details on how to tweak the sketch.
Note: Many variations are possible, depending on your clock's hardware; but this covers most cases.
- Press Select to cycle through the clock's functions. Some return to Time after a few seconds.
- To set, hold Select 'til the display flashes; use Adjust to set, and Select to save.
| Function | Looks like | Notes |
|---|---|---|
| Time | 12 34 56 |
The time of day. You can choose 12h or 24h format in the options menu (1). When setting, it's in 24h format (so you can tell AM from PM) and the seconds will reset to :00 when you save. The clock keeps time during power outages and compensates for temperature effects. If your clock is controlling an appliance (relay in switched mode), use Adjust here to switch it on and off manually. |
| Date | _2 _4 _0(for Sun 2/4) |
You can choose the date format in the options menu (2). Setting is done in three stages: first year, then month, then date. Weekdays are: 0=Sun, 1=Mon, 2=Tue, 3=Wed, 4=Thu, 5=Fri, 6=Sat |
| Alarm | _7 00 1_ |
Shows alarm time (always in 24hr format) and on/off status on 5th tube (1=on, 0=off) and by display brightness (bright=on, dim=off). Use Adjust to switch on/off. Hold Select to set time (same way as Time). When alarm sounds, press Select to snooze, or hold for 1sec (followed by a short beep) to silence the alarm for the day. Options menu lets you restrict the alarm to your workweek or weekend only. In a power outage, the alarm will remain set, but it will not sound if power is disconnected at alarm time. |
| Timer | __ __ _0 |
A countdown timer, in hours, minutes, and seconds; or 0 when stopped. Can be set to the minute, up to 18 hours. Begins running as soon as you set it, and will continue to run in the background if you change to a different function. To cancel while running, hold Select. When timer runs out, press Select to silence. If power is lost, the timer will reset to 0. Can be configured to work as an interval timer in the options menu (10), or as an appliance timer instead (relay in switched mode). |
| Day counter | _1 23 __ |
Shows the number of days until/since a date you specify. Set the same way as Date. |
| Temperature | __ 38 25 |
(Disabled by default.) Shows the temperature of the onboard DS3231 chip (e.g. 38.25°C – I think). May not be very useful as it tends to read higher than ambient temperature and its tolerance is low. |
| Tube tester | 88 88 88 |
(Disabled by default.) Cycles through all the digits on all the tubes. |
- To access this, hold Select for 3 seconds until you see a single
1on the hour tubes. This indicates option number 1. - Use Adjust to go to the option number you want to set (see table below); press Select to open it for setting (display will flash); use Adjust to set; and Select to save.
- When all done, hold Select to exit the options menu.
| Option | Settings |
|---|---|
| 1. Time format | 1 = 12-hour 2 = 24-hour (time-of-day display only; setting times is always done in 24h) |
| 2. Date format | 1 = month/date/weekday 2 = date/month/weekday 3 = month/date/year 4 = date/month/year 5 = year/month/date Note that four-tube clocks will display only the first two values in each of these options. |
| 3. Display date during time? | 0 = never 1 = date instead of seconds 2 = full date (as above) every minute at :30 seconds 3 = same as 2, but scrolls in and out |
| 4. Leading zero in hour, date, and month? | 0 = no 1 = yes |
| 5. Digit fade | 0–20 (in hundredths of a second) |
| 6. Auto DST | Add 1h for daylight saving time between these dates (at 2am): 0 = off 1 = second Sunday in March to first Sunday in November (US/CA) 2 = last Sunday in March to last Sunday in October (UK/EU) 3 = first Sunday in April to last Sunday in October (MX) 4 = last Sunday in September to first Sunday in April (NZ) 5 = first Sunday in October to first Sunday in April (AU) 6 = third Sunday in October to third Sunday in February (BZ) |
| 7. Alarm days | 0 = every day 1 = work week only (per settings below) 2 = weekend only |
| 8. Alarm snooze | 0–60 minutes. 0 disables snooze. |
| 9. Alarm signal | 0 = beeper 1 = relay (if in switch mode, will stay on for 2 hours) (Clocks with both beeper and relay only) |
| 10. Alarm beeper pitch | Note number on a piano keyboard, from 49 (A4) to 88 (C8). Some are louder than others! (Clocks with beeper only) |
| 11. Timer signal | 0 = beeper 1 = relay (if in switch mode, will stay on until timer runs down) (Clocks with both beeper and relay only) |
| 12. Timer interval mode | 0 = count down and stop 1 = count down and restart (interval mode) (Clocks with beeper and/or pulse relay only) |
| 13. Timer beeper pitch | Set the same way as the alarm pitch, above (Clocks with beeper only) |
| 14. Strike | Make noise on the hour: 0 = off 1 = single beep 2 = pips 3 = strike the hour (1 to 12) 4 = ship's bell (hour and half hour) Will not sound during day-off/night-off (except when off starts at top of hour) (Clocks with beeper or pulse relay only) |
| 15. Strike signal | 0 = beeper 1 = relay (Clocks with both beeper and pulse relay only) |
| 16. Strike beeper pitch | Set the same way as the alarm signal pitch, above. If using the pips, 63 (987 Hz) is closest to the real BBC pips frequency (1000 Hz). (Clocks with beeper only) |
| 17. Night-off | To save tube life and/or preserve your sleep, dim or shut off tubes nightly when you're not around or sleeping. 0 = none (tubes fully on at night) 1 = dim tubes at night 2 = shut off tubes at night When off, you can press Select to illuminate the tubes briefly. |
| 18. Night starts at | Time of day. |
| 19. Night ends at | Time of day. Set to 0:00 to use the alarm time. At this time (whether night-off/alarm is enabled or not), all tubes will briefly cycle through all digits at full brightness to help prevent cathode poisoning. |
| 20. Day-off | To further save tube life, shut off tubes during the day when you're not around. 0 = none (tubes fully on during the day) 1 = clock at work (shut off all day on weekends) 2 = clock at home (shut off during work hours) When off, you can press Select to illuminuate the tubes briefly. |
| 21. First day of work week | 0–6 (Sunday–Saturday) |
| 22. Last day of work week | 0–6 (Sunday–Saturday) |
| 23. Work starts at | Time of day. |
| 24. Work ends at | Time of day. |
To reset the options menu settings to "factory" defaults, hold Select while connecting the clock to power.
A number of hardware-related settings are specified in consts at the top of the sketch, which can be edited to suit the clock's hardware configuration. These include:
- How many tubes in the display module. Default is 6; small display adjustments are made for 4-tube clocks.
- Which functions are enabled. Default is all but temperature and tube tester.
- Which input pins are associated with the Select and Adjust controls.
- What type of Adjust controls are equipped: pushbuttons (default) or rotary encoders.
- What type of signal outputs are equipped: a piezo beeper (default) and/or a relay.
- Signal duration (default 3min) and piezo pulse duration (default 500ms)
- If relay is equipped, relay mode:
- In switched mode (default), the relay will be switched to control an appliance like a radio or light fixture. If used with timer, it will switch on while timer is running (like a "sleep" function). If used with alarm, it will switch on when alarm trips; specify relay switch duration (default 2 hours).
- In pulse mode, the relay will be pulsed, like the beeper is, to control an intermittent signaling device like a solenoid or indicator lamp; specify relay pulse duration (default 200ms).
- Soft alarm switch enabled: default is yes; it is switched with Adjust while viewing the alarm time. Change to no if the signal output/appliance has its own switch on this relay circuit; the clock's alarm will be permanently on.
- Soft power switch enabled (switched relay only): default is yes; appliance can be switched manually with Adjust while viewing the time of day. Change to no if the appliance has its own power switch (independent of this relay circuit) or does not need to be manually switched.
- Various other durations for things like scrolling speed, set mode timeouts, short and long button holds, "hold to set faster" thresholds, etc.
You can also set the defaults for the options menu to better suit the clock's intended use.
To compile the edited sketch: You will need to add the ooPinChangeInt and NorthernWidget DS3231 libraries to your Arduino IDE.
To upload the sketch to the UNDB: if it doesn't appear in the IDE's Ports menu (as a USB port), your UNDB may be equipped with an Arduino clone that requires drivers for the CH340 chipset.