Show HN: F32 – An Extremely Small ESP32 Board

As part of a little research and also some fun I decided to try my hand at seeing how small of an ESP32 board I can make with functioning WiFi.

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jacquesm 6 hours ago | parent | next [-]

If you add another GPIO and make a silicone mold you could make an in-cable eavesdropper on USB connections that streams out the data via the wifi. That would be a pretty scary tool in the right circumstances.

	▲	atemerev 6 hours ago \| parent [-]
		These cables can be bought for like $200 mostly legally.

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Swannie 25 minutes ago | parent | prev | next [-]

I was thinking "how much smaller than the cheap 30mm x 25mm boards on AliE can you go?" ... much smaller!

Very nice.

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tmpfs a day ago | parent | prev | next [-]

This is a very cool experiment, even if the board doesn't end up being that practical (the antenna hack is going to be an ongoing issue I think) your documentation looks great at a glance!

	▲	pegor a day ago \| parent [-]
		Thank you! I agree, antenna definitely needs some improvement.

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stavros 2 hours ago | parent | prev | next [-]

This is great, well done! I don't know where I'd use this, but I'd definitely want to use it.

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Rebelgecko 4 hours ago | parent | prev | next [-]

Really cool. I just ran into a situation where it would be handy to have a small Bluetooth device that plugs into USB-C. However soldering something like this seems a bit beyond me, is there a more turnkey solution?

	▲	dotancohen an hour ago \| parent [-]
		The company that printed the PCB, PCBWay, also offers PCBAs. They're really not expensive, though you might need to order in batches of multiples of five.

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anyg 18 hours ago | parent | prev | next [-]

If it is a little bigger to incorporate a bigger chip antenna and some GPIO pins, it is going to be very useful for a lot of IoT projects!!

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margalabargala 6 hours ago | parent | next [-]

The XIAO series of ESP32s is exactly that.

They are 4x the size though, almost exactly double in both length and width.

https://wiki.seeedstudio.com/XIAO_ESP32C3_Getting_Started/

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dotancohen an hour ago | parent | next [-]

It's also got 15 times as many GPIO pins as the board in the fine article.

And this PCBA will be smaller than the battery in most applications anyway.

	▲	margalabargala an hour ago \| parent [-]
		It only has 14 pins, 3 of which are 5v, 3.3v, and ground, so slight exaggeration :-) point taken though

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sho_hn 2 hours ago | parent | prev [-]

These are quite lovely. Ceramic SMD antennas are awesome.

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pegor 8 hours ago | parent | prev | next [-]

Definitely would be more functional with more of the GPIOs exposed.

	▲	forsalebypwner 6 hours ago \| parent [-]
		If you want an ESP32 dev board with GPIOs exposed there are dozens (or hundreds, maybe thousands) of other options out there. It makes sense not to expose them when you're going for the smallest possible footprint.

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PunchyHamster 7 hours ago | parent | prev [-]

there is plenty of those already and not all too hard to make yourself, see LilyGo T01-C3

Its of format of original ESP8 so you get serial + 3 IO pins

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allenrb 41 minutes ago | parent | prev | next [-]

Jesus. You had me at “hand-soldered 01005 components”.

I’m tempted to try a few of these just to see how disastrous my build efforts are.

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ingen0s 6 hours ago | parent | prev | next [-]

Nice work, kudos!

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puzzlingcaptcha 4 hours ago | parent | prev | next [-]

01005? Oh no no no. I can barely do 0402s by hand and those are _2.5x_ larger.

	▲	joemi an hour ago \| parent \| next [-]
		Wouldn't 0402 be 4x larger (if comparing lengths) or 16x larger (if comparing areas), not 2.5x? Edit: Nevermind, I was wrong. I see now that the sizes don't actually directly correspond to the number codes! 01005 is 0.4mm x 0.2mm and 0402 is 1mm x 0.5mm. That's annoyingly confusing, IMO.
	▲	sho_hn 3 hours ago \| parent \| prev \| next [-]
		With one of those mini-hotplates for reflow soldering and a LCD microscope it's still fairly doable.
	▲	VTimofeenko 4 hours ago \| parent \| prev [-]
		FWIW, there's a step by step soldering guide in the readme: https://github.com/PegorK/f32#building-the-f32 It looks doable, but of course a lot of carefulling is required when placing the components.

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Gys 5 hours ago | parent | prev | next [-]

> PCBWay does also offer assembly services

Seriously? For a tiny board like this also? Genuine question.

	▲	kube-system 5 hours ago \| parent [-]
		yes, but they use a machine, they don't do it by hand.

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NuclearPM 17 hours ago | parent | prev [-]

> This can be seen in my highly necessary depiction below.

I love this. Fun and insightful article. Thank you.

	▲	pegor 8 hours ago \| parent [-]
		Thanks for checking it out!