EHLPC is meant to be used on ESP-based MAX7219 Digit Display Clocks using ESPHome. So far, it works with an un-named Aliexpress Clock. It can probably be adapted for use with other MAX7219 Digit clocks. And, of course, it's ESPHome, so it's only limited by your imagination and skill.
A lot of inspiration is taken from the EHMTXv2 project... but with a monochrome LED Display.
Using this clock requires external font files. I prefer my own MatrixClockFonts but ESPHome supports a variety of fonts, including TTF.
For now, the file EHLPClock.yaml contains the full YAML code, including a lengthy lambda that makes it all work. At some point, I may turn this into a custom component for ESPHome... but for now, you'll just to have carefully edit the YAML to suit your needs.
This is the link on Aliexpress I have personally used but I am sure there are others: https://www.aliexpress.com/item/1005005704533418.html
Here is my clock, using the Matrix Font and a bit of paper sandwiched between the LED display and the acrylic.
Flashing is dead-simple. Hold the 'Download' button while powering-on the clock or by pressing the reset button.
This is ESPHome, so it's not pretty but very functional. You should set your wifi information in the YAML and edit it carefully.
If using this device on a network outside your usual, ESPHome will, after 10 seconds (set by the YAML), give up trying to connect to its "home" network and enter AP mode. You should then connect to the hotspot (with a mobile phone) and then go to 192.168.4.1 in a browser to select which local wifi network you would like it to connect to. The clock will display its IP address on boot and also by holding down the set button for more than 1 second. When returning home, you will have to go through this process again. Be sure if you are using this clock as a travel clock to NOT use Home Assistant as a time source (it doesn't by default anyways).
There does appear to be some errors with "Component preferences took a long time for an operation" but it only happens when saving persistent variables to flash and doesn't seem to affect functionality, unless you try to change a variable during this moment.
Ideally, this would look a lot prettier than it does but there's not a lot I can with the default ESPHome WebUI.
There's only one useable button on this clock but thanks to multi-click, we can use it for a few functions.
| Download Button | Functionality |
|---|---|
| Short-click | Toggle date display mode on/off |
| Double-click | Toggle 12/24-hour mode on/off |
| Short-click, long-press | Toggle Time Zone Offset on/off |
| Long-press 1 second | Show the clock's IP address (or other wifi status) |
| Long-press 5 seconds | Toggle the Wifi Stop Seek on/off (see below) |
Of course, this is ESPHome, so you can change the button functions by editing the YAML if you wish.
This clock has a rotation sensor. It seems to be just a mercury-like bulb that detects if the clock has been flipped. This is functional to flip the clock but you could also use it for other things if you wish.
The clock can display the date at configurable intervals. The display interval checks how long the clock was displayed for and then displays the date for the specified time (in seconds). Keep in mind that displaying the message from the Home Assistant integration will not interrupt this count, so I recommend choosing sane and even numbers.
Time can be synced to the Internet at configurable intervals between 1 - 24 hours, provided the wifi network is connected.
It's up to you how to handle time zones. I prefer to keep my home time zone (Korea) as the one I live in and use the offset option according to the time difference of with Korea. You can set an offset with a number that is a positive or negative value with decimal places (ie. 2, -2, 12.5).
You could also set your time zone to GMT and make the default offset match your home. I haven't really experimented with this way so your mileage may vary, especially if you live in an area that uses Daylight Savings Time.
I have allowed steps of 0.25 (equal to 15 minutes) but I notice ESPHome does not enforce those steps. It is possible to set an offset like 0.01 (which would be 36 seconds). Be careful.
This is disabled by default but by turning it on, the clock will disable its wifi radio after a configurable time if the network connection is dropped. Note that this does not turn wifi off if connected, it's merely a timeout for when the configured wifi connection cannot be made. This is meant as a power-saving feature in the event of a power blackout.
Under normal conditions, when an ESPHome device loses wifi connectivity, it will continuously seek out a wifi connection or activate a hotspot to allow configuring a wifi connection. While in this non-connected state, the clock will use more power than usual. If you have a coin-cell battery that maintains the RTC during a blackout, you could re-connect the clock to a powerbank or some other power source and it will continue to function.
Please note that this also means that the clock will not try to connect to wifi again (this will be indicated on the screen as "Wifi Off" when long-pressing the button), unless you reset the power, which just means unplugging it and plugging it back in again.
Do not set this time too short. I have allowed 60 seconds minimum in the options but this could mean your clock stops trying to connect to wifi just because your router rebooted or the wifi was a bit sketchy. The default is 120 seconds which I think is enough time for even the slowest router to reboot, but it's your choice. Also keep in mind that this time will affect how long the configuration hotspot is available for. The hotspot will activate after 10 seconds (lowered from 60 seconds which is ESPHome default).
You can enable or disable this mode by holding the button for 5 seconds to toggle the function. The wifi will be turned on again if it has been turned off.
| Status / Mode | Power usage (24 hours) |
|---|---|
| Connected | 3000 mAh |
| Stop Seek Off & No Wifi | 3200 mAh |
| Stop Seek On & Wifi Off | 1600 mAh |
While the clock is connecting to wifi or while in hotspot mode, the blue LED will pulse on and off. In regular mode, the LED will turn on or off will be every 1 second. If Stop Seek is enabled, the led will pulse on or off every 2 seconds. If connected to Wifi or Stop Seek (as above) is active, the LED will turn off completely.
This example will send a message that will display for 3 seconds before reverting to the clock for 5 seconds, and repeat until 20 seconds is finished (if it is displaying the message, it will finish that last 3 seconds).
| Date | Release Notes |
|---|---|
| 2023.11.16 | Wifi Stop Seek, 2nd date screen, time zone offset, alt time zone |
| 2023.10.22 | Show date on intervals |
| 2023.09.10 | Basic functionality, HA integration, rotation |
Some people would prefer to use Tasmota. I did use Tasmota at first but I found it a bit lacking, namely that it doesn't seem possible to replace the default font. I made some notes that I'll include here:
First, using Gitpod, add these lines to user_config_override.h:
#define USE_DISPLAY_MAX7219_MATRIX
#define USE_I2C
#define USE_DS3231
#define USE_RTC_CHIPS
Then run:
platformio run -e tasmota-display
The GPIOs:
| Function | PIN |
|---|---|
| SCL | GPIO4 |
| SDA | GPIO5 |
| CLK | GPIO14 |
| MOSI | GPIO13 |
| CS | GPIO15 |
| LEDLINK | GPIO2 |
| SWITCH 1 (Download button) | GPIO0 |
| SWITCH 2 (Rotation Sensor) | GPIO16 |
Some useful console commands (it'll at least get you a functional display, though you may need to reset the power first):
Backlog DisplayWidth 32; DisplayHeight 8; DisplayModel 19; DisplayMode 0; DisplayRotate 1
Backlog Power 1; DisplayClock 1
What started my curiousity (a long discussion on ESP-based 7-segment clocks): arendst/Tasmota#15788
Trombik's ESPHome Component for the DS1302 RTC (used on the 303): https://github.com/trombik/esphome-component-ds1302
About outputting to the MAX7219 Digit Display: https://esphome.io/components/display/max7219digit.html
ESPHome's Display: https://esphome.io/components/display/index.html