https://github.com/anachrocomputer/hexclock
Arduino sketch to display the time in hex
https://github.com/anachrocomputer/hexclock
arduino clock hexadecimal octal
Last synced: about 2 months ago
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Arduino sketch to display the time in hex
- Host: GitHub
- URL: https://github.com/anachrocomputer/hexclock
- Owner: anachrocomputer
- Created: 2024-06-14T19:58:24.000Z (almost 2 years ago)
- Default Branch: main
- Last Pushed: 2026-04-16T21:55:25.000Z (about 2 months ago)
- Last Synced: 2026-04-16T23:32:03.612Z (about 2 months ago)
- Topics: arduino, clock, hexadecimal, octal
- Language: C++
- Homepage:
- Size: 28.3 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# HexClock #
This Arduino sketch implements a clock with four different display formats:
* Ordinary hours, minutes, and optionally seconds
* Octal time, 00000 to 07777
* Hexadecimal time, 0x0000 to 0xFFFF
* Decimal or percentage time, 00.00 to 99.99
The actual display is optional at present,
as four 7-segment digits on an LED display.
Six digits would only be needed to show seconds in standard time format.
## Optional Display ##
The sketch generates standard
Arduino serial output at 9600 baud.
This is useful for debugging.
The sketch will send the time in hex to either an HP HMDL2416 16-segment
four-digit display or to four PCBs of my own design ("LedHex").
The HMDL2416 data bus is connected to the ATmega PORT D and Arduino pins 11 and 12,
and the control signals are connected to other Arduino digital I/O pins.
## User Controls ##
The pushbutton on Arduino A0 is used to switch between display modes
at run-time.
Pressing it will cycle through from the inital HEX to OCTAL,
DECIMAL, and STANDARD (then back to HEX).
No user controls are provided to set the time.
## Example Times ##
| Ordinary | Hexadecimal | Octal | Percentage |
|----------|-------------|-------|------------|
| 00:00:00 | 0000 | 0000 | 00.00 |
| 01:30:00 | 1000 | 0400 | 06.25 |
| 03:00:00 | 2000 | 1000 | 12.50 |
| 04:30:00 | 3000 | 1400 | 18.75 |
| 06:00:00 | 4000 | 2000 | 25.00 |
| 07:30:00 | 5000 | 2400 | 31.25 |
| 09:00:00 | 6000 | 3000 | 37.50 |
| 10:30:00 | 7000 | 3400 | 43.75 |
| 12:00:00 | 8000 | 4000 | 50.00 |
| 13:30:00 | 9000 | 4400 | 56.25 |
| 15:00:00 | A000 | 5000 | 62.50 |
| 16:30:00 | B000 | 5400 | 68.75 |
| 18:00:00 | C000 | 6000 | 75.00 |
| 19:30:00 | D000 | 6400 | 81.25 |
| 21:00:00 | E000 | 7000 | 87.50 |
| 22:30:00 | F000 | 7400 | 93.75 |
| 23:59:59 | FFFF | 7777 | 99.99 |
### Pinout ###
| Arduino | Signal | HMDL2416 | HMDL2416 Pin | DS3231 Signal |
|---------|---------|----------|--------------|---------------|
| D10 | D10 | /CE1 | 1 | |
| GND | GND | /CE2 | 2 | |
| +5V | Vcc | /CLR | 3 | |
| GND | GND | CUE | 4 | |
| +5V | Vcc | /CU | 5 | |
| D7 | D7 | /WR | 6 | |
| D9 | D9 | A1 | 7 | |
| D8 | D8 | A0 | 8 | |
| +5V | Vcc | Vcc | 9 | Vcc |
| GND | GND | GND | 10 | GND |
| D0 | TxD | | | |
| D1 | RxD | | | |
| D2 | D2 | D2 | 13 | |
| D3 | D3 | D3 | 14 | |
| D4 | D4 | D4 | 15 | |
| D5 | D5 | D5 | 16 | |
| D6 | D6 | D6 | 17 | |
| D11 | D0 | D0 | 11 | |
| D12 | D1 | D1 | 12 | |
| +5V | Vcc | /BL | 18 | |
| A0/D14 | MODESW | | | |
| A4/D18 | I2C SDA | | | I2C SDA |
| A5/D19 | I2C SCL | | | I2C SCL |
MODESW is connected to a 10k pull-up resistor and a tact-switch to GND.
It's used as a digital input, not analog (Arduino digital pin 14).
## Real-Time Clock ##
A non-volatile real-time clock module using the DS3231 should be connected
to the Arduino's I2C pins (A4 and A5) along with 10k pull-up resistors.
This will be used to read the time and date at start-up.
A line of code to set the DS3231 is included in 'setup()',
commented-out.
## TODO ##
The display will work with any type of 7-segment display,
e.g. vacuum fluorescent, LED, LCD,
Panaplex, Numitron,
electromechanical flip-type.
If we limit ourselves to octal times (0000-7777) then the display will be
compatible with Nixie tubes,
edge-lit digits,
projection displays,
and any other type of decimal (0-9) digit displays.
Some Numitron displays have Russian Postcode digits,
with two additional diagonal segments within the usual 7-segment arrangement.
Would be nice to support those if I had some.
Synchronise internal Arduino time with the (more accurate) DS3231 I2C
real-time clock chip.
Probably best to do this every 90 minutes/6.25%/0x1000/0400,
i.e. 16 times per day.
Find a better way to set the time without needing to recompile the code.
Implement other types of serially-interfaced display: TM1622,
MAX7219, I2C 14-segment.
Advanced goal: make this into a watch.
Round OLED display?
Tiny 7-segment?
LCD for low power?