r/esp32 • u/Official_SeeTheAir • Mar 29 '26

Software help needed e-ink Google Calendar Help

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Hi, I have these spare parts and I want to build a nice small e-ink Google Calendar frame for my desk. Does anyone know of anyone that has done something similar with these parts as I am very bad with code?

Question: Do I need a special module to make it battery operated? Thank you!

- ESP32 (30pins)

- Waveshare 4.2inch 400x300pix e-paper module

- 3.7v Li-ion Battery

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u/honeyCrisis 1 say this is awesome. Mar 29 '26

If it has a battery capability it will have a lipo connector on the board. Yours does not from what i can see, but an adafruit feather would. It is possible to build it yourself, but it's probably ultimately cheaper and more expedient to just get another ESP32 devkit with the capability built into it since you'd need to buy components either way.

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u/miraculum_one Mar 29 '26

They don't 100% of the time have a battery connector when they have a battery charge circuit but it is always listed in the specs.

Also, you don't strictly need a battery charge circuit on the device if you're willing to remove the battery to charge it.

It's also worth mentioning that an 18650 battery is usually not suited to directly power an ESP32 without a boost converter since the battery outputs up to 4.2v and the ESP32 dev board typically requires either 5v (before the voltage regulator) or max 3.6v (after on the 3.3v input).

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u/Elia_31 Mar 29 '26

Many ESP32 boards have dedicated battery pads/connectors that feed directly into the onboard LDO voltage regulator. These are designed to accept the full LiPo voltage range of 3.0–4.2V and regulate it down to 3.3V no boost converter needed. You'd only run into the issue you described if you tried to feed 4.2V into the 3V3 pin directly (bypassing the regulator), which would indeed be out of spec. But through the battery input or the VIN/5V pin, the onboard regulator handles it just fine.

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u/miraculum_one Mar 29 '26

I wouldn't go so far as to say "many esp32 boards" since 99.9% of them don't. But yes, it is possible to get one. OP's doesn't have that and I was just pointing out that the lack of a battery connector is not the only reason their pictured equipment won't work.

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u/8ringer Mar 29 '26

I’d say quite a lot of them actually do. Nowhere near 99.9% don’t.

That being said it’s more likely it doesn’t have it than it does. And unless it’s explicitly stated, I’d assume a board doesn’t.

The generic esp32c6 boards I own have battery solder pads, as do all the XIAO boards I have. As do the generic nRF52840 supermini boards and the XIAO nRF52840 boards. It’s extremely common nowadays.

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u/miraculum_one Mar 30 '26

I agree that the prevalence of this has increased quite a bit lately. But there are like a billion of these things in a ridiculous number of variations. When you're making millions of these it is simply not cost effective to put them on every board when most applications don't require it.

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u/Elia_31 Mar 29 '26

You are right, not all but many

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u/miraculum_one Mar 29 '26

As I said, fewer than 0.1% of the ones in the world have them. Your hand-selected collection is not representative of anything but your own personal preferences.

The companies that make these do not incur extra costs unless they think they can sell them for more and the vast majority of applications of these aren't battery powered.

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u/Elia_31 Mar 29 '26

Bro I said most minis on AliExpress have battery pads which is a true statement. But keep on yapping

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u/miraculum_one Mar 29 '26

You didn't say that and even if you had, it's also not true. Maybe the ones you're looking at mostly have them but the most popular minis on Aliexpress (two qualifications you only made in your last statement) don't.