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Simple illuminated time display that can be driven over USB?

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sparkydog:
My cable company recently decided to remotely brick my DVR. This is annoying for a number of reasons, but in particular... I was rather used to it doubling as a clock.

Now, I really don't want much from a clock, just:

* It should be self-illuminated light-on-dark (i.e. LED/VFD/OLED, not LCD).
* It should use or support 24-hour time.
* I shouldn't have to set it. Ever. (Not even if the DST rules change.)
Is this so much to ask?

Well, apparently it is, because while it's trivial to find two-out-of-three in various combinations, almost nothing satisfies all three. (If this is reminding you of this other, recent thread... yup. Except I'm looking for self-illuminated.) Frills such as seconds, date, temperature and weather are acceptable but not required. I wouldn't mind an off-the-shelf product, but the only one I can find that checks all the above boxes is this, and I don't like the seconds being a different size. (I'm not in love with the dot-matrix style digits, either.) I'd also prefer to avoid something that needs to be hooked up to WiFi, and I will not use anything that requires installing an app.

Now... mitigating my woes, I do happen to have a Linux "server" near where I want the clock, which satisfies the third point via the magics of NTP and software updates. In fact, if I could just hook an always-on display to that, it would solve my problem nicely.

Is there a modest-sized (at least 3"×1" but not larger than 18"×5") OLED screen that I can control from a PC USB port from userland software, but not as an X/Wayland display? Or is there any four-digit seven-segment (with colon, please!) time display (preferably with 1" to 3" high digits and preferably white, blue, or at least not-red) that can be controlled from a PC USB port? Basically, I want something that lets me run software on the PC to update the display when the minute changes. (Something that can also be powered off the same port would be ideal, but isn't strictly necessary.)

I'm not adverse to adding a MCU to the mix and/or scavenging a display from some off-the-shelf clock. (I suppose that, with enough effort, I could coax an old smartphone into serving, but I'd prefer something a little more straight forward.)

robert.rozee:
GPS module, small colour LCD screen, and a single-chip BASIC computer:

https://geoffg.net/SuperClock.html

personally, i'd put a small toggle switch on the back to select daylight savings option, you only need to flip it twice a year.


cheers,
rob   :-)

PCB.Wiz:

--- Quote from: sparkydog on April 19, 2024, 09:41:43 pm ---Is there a modest-sized (at least 3"×1" but not larger than 18"×5") OLED screen that I can control from a PC USB port from userland software, but not as an X/Wayland display? Or is there any four-digit seven-segment (with colon, please!) time display (preferably with 1" to 3" high digits and preferably white, blue, or at least not-red) that can be controlled from a PC USB port?

--- End quote ---

I recently went looking for a largish 7-segment display, with properly proportioned digits.
There are not many around.

This is nice and large, 30.5mm digits,  and will have very good viewing angles, but is glass and pins only, so you need to add a segment driver / board.
https://www.aliexpress.com/item/1005003087294038.html

Smaller 7-seg do exist, like this from Adafruit
https://www.adafruit.com/product/5581

and smaller ones from Aliexpress  10mm high digits.
https://www.aliexpress.com/item/1005004102385524.html
or
https://www.aliexpress.com/item/32924015493.html

or 15m high, but no colon
https://www.aliexpress.com/item/32944755027.html


--- Quote from: sparkydog on April 19, 2024, 09:41:43 pm ---I'm not adverse to adding a MCU to the mix and/or scavenging a display from some off-the-shelf clock. (I suppose that, with enough effort, I could coax an old smartphone into serving, but I'd prefer something a little more straight forward.)

--- End quote ---
The Pi-PICO may be the best building block with a OLED or TFT ?

eg This OLED is 77 x 19mm  active area, 256x64 pixels.
https://www.aliexpress.com/item/1005006051449911.html


There are wifi ready clocks
https://www.aliexpress.com/item/1005005609244308.html
but it's unclear if they are properly global in timezone handling ?

Maybe this one does ? 1.2" displays
https://www.aliexpress.com/item/1005005430295742.html

sparkydog:

--- Quote from: robert.rozee on April 20, 2024, 02:03:01 am ---GPS module, small colour LCD screen, and a single-chip BASIC computer:

https://geoffg.net/SuperClock.html

personally, i'd put a small toggle switch on the back to select daylight savings option, you only need to flip it twice a year.

--- End quote ---

The problem with a flip-switch is that I have to flip it. That means the clock is going to be wrong when I wake up after a time change, which is the most important time for it to be right. (Also, how do GPS-based clocks account for leap seconds? Are they just off by a few seconds? Do they use a manual offset?)

Also, I'm really looking for something that doesn't involve blocking light. 🙂 There are plenty of LCD screens floating around if I wanted to go that route. There's a reason I'm looking for OLED specifically, or for a segmented display that can light individual segments (which is to say, pretty much any such display).

The best I've seen are some 5.5" displays, but they all seem to take HDMI. (Which, okay, considering they're also 1080p... and priced accordingly...) That would be "workable" but would need something like a Pi to drive the display.

Are there MCUs that can be powered off USB and support some sort of communication over the same USB? Or would I have to use a USB-to-serial with a separate power supply to talk to an MCU from a computer?

PCB.Wiz:

--- Quote from: sparkydog on April 22, 2024, 09:19:30 pm ---
Are there MCUs that can be powered off USB and support some sort of communication over the same USB? Or would I have to use a USB-to-serial with a separate power supply to talk to an MCU from a computer?

--- End quote ---
Sure, any USB MCU can do.
You need to link their USB code, which can have varying quality…
People often use  serial bridge to skip that hassle.

Some MCU can boot using USB.

eg The pi-pico can boot from USB, and I expect has modest speed python usb support, which should be fine in your case.

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