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.
I'm still in the early stages but it's still pretty useable.
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
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 30 seconds, 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. I'll start with 2 for now.
| Download Button | Functionality |
|---|---|
| Short-click | Toggle 12/24-hour mode |
| Long-press 1 second | Show the clock's IP address |
Of course, this is ESPHome, so you can change the button functions by editing the YAML. There's also a rotation sensor. Originally it was supposed to allow the clock display to flip 180 degrees but I'm not sure I can integrate this functionality.
(Not included yet but will be soon.)
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 with Korea. The offsets I include are mostly for demonstration purposes. You can use positive or negative values and decimal places in your choices (ie. 2, -2, 1.5).
You could set your home 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.
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).
Some people would prefer to use Tasmota. I did use Tasmota at first but I found it a bit lacking. 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