Hardware recommendations

Projects General Guidance
1

I’m designing a project and would like to get some recommendations from the forum.

I would like to build 20 synchronized LED tubes. About 12 LEDs per tube. This is for indoor use in a dimly lit room.
Each unit should be battery powered with a run time of 6-10 hours.
Units will be placed in the same room a few meters apart max.
Units should synchronize effects, but timing is not super-critical.
Units should also be able to display an effect individually.
No external wires.
Effects will be centrally controlled .
An e-ink display would be nice.
Budget for electronics should be under $50 per unit.

What hardware and communications protocol do y’all recommend?

Thanks.

2

Esp32 devboards with onboard 18650 battery holder? Or with separate power bank?
You didn't tell anything about power draw, neither LED-tube voltage.
For communication you can pick one between HTTP requests, UDP, Espnow, BLE, bluetooth classic...

3

if the environment is not super noisy in the 2.4Ghz space then I agree that an ESP32 or ESP8266 with ESP-NOW and 12 WS2812B in a Strip with a led and a resistor, a large enough 18650 Li-Ion Battery + a 5V Boost Converter to power the leds would get you going.

The most expensive item will likely be the battery. You could pick a TinyPICO or an ESP32C3 like the XIAO

The capacity of the battery depends on how often the modules communicate between each other and how bright the leds need to be

You won't guarantee micro-second sync but with a master broadcasting a "GO" message to all the tubes will be received visually at the same instant

4

I like the look of the esp32 boards. I was already thinking of 2.4GHz for comms and I don’t think I’ll run into too much interference, but I plan on taking them to different sites, so it could vary.

Wireless traffic would probably happen about once or twice in ten minutes.

E-ink updates would be even less frequent.

Was already planning on 2812 addressable LEDs. They would be continually lit for the 8-ish hours at probably 40% power (random guess).

5

Let's do a calculation 12 LEDS 60ma/LED40% power * 8hr = 2304 ma-hrs. This is marginal using 18650 Li-ion cells even before considering the conversion to 5V. Converting to 5V will require more current. (2300 * (5/3.7))/80% efficiency = ~4000 ma-hrs

The ratings for 18650 Li-ion cells are for a 3.0V end point and, in many cases, fantasies rather than reality, particularly for claims above 2300 ma-hrs.

You may want to think about 6V SLA batteries and a buck converter to 5V.

6

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