[HN Gopher] Show HN: F32 - An Extremely Small ESP32 Board
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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.
Author : pegor
Score : 290 points
Date : 2025-11-19 20:09 UTC (2 days ago)
(HTM) web link (github.com)
(TXT) w3m dump (github.com)
| tmpfs wrote:
| 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 wrote:
| Thank you! I agree, antenna definitely needs some improvement.
| wkat4242 wrote:
| You should take the metal of the USB connector into account.
| This will significantly alter the emission pattern of the
| antenna. Try to find a radio amateur in your area, we have
| equipment to measure and software to predict antennas.
| anyg wrote:
| 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!!
| pegor wrote:
| Definitely would be more functional with more of the GPIOs
| exposed.
| forsalebypwner wrote:
| 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.
| stavros wrote:
| I don't know, I see enough space for four GPIOs there. Not
| holes, obviously, but pads should be very workable.
| imtringued wrote:
| It could be even smaller without that USB C port and have
| more GPIO pads.
| PunchyHamster wrote:
| 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
| margalabargala wrote:
| 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/
| sho_hn wrote:
| These are quite lovely. Ceramic SMD antennas are awesome.
| dotancohen wrote:
| 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 wrote:
| It only has 14 pins, 3 of which are 5v, 3.3v, and ground,
| so slight exaggeration :-) point taken though
| lelanthran wrote:
| These are nifty. I've used them in production, but if you
| want to make used of the charger it's difficult.
| venusenvy47 wrote:
| Can anyone suggest a small module that supports 5 GHz WiFi?
| NuclearPM wrote:
| > This can be seen in my highly necessary depiction below.
|
| I love this. Fun and insightful article. Thank you.
| pegor wrote:
| Thanks for checking it out!
| unwind wrote:
| Me too, but that particular picture was confusing. Shouldn't
| the board be with the human, 120 ft from the wifi access point
| being connected to? Now it looks as if the human screams at the
| board from 120 ft away, or something.
|
| Other than that, hugely impressive project of course, it makes
| any board I've tried to design/assemble look impossibly huge.
| :)
| nhecker wrote:
| No, I think the human holds a smartphone, is standing 38m
| away from the board, and is still able to connect to the
| distant board via the open Access Point it makes available.
| It's a testament to the communication between the Access
| Point and the human connecting to it.
|
| FTA:
|
| > In a clear line of sight test with the f32 placed about 3ft
| off the ground I was able to connect and perform
| scans/control the LED at roughly 120ft!
|
| Fun fact, at that size the whole f32 is smaller than the
| wavelength of the radio waves it's using for 2.4GHz WiFi. Not
| that this is unique by any stretch, but it's still fun to
| think about. (Edit: formatting)
| ingen0s wrote:
| Nice work, kudos!
| jacquesm wrote:
| 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 wrote:
| These cables can be bought for like $200 mostly legally.
| Gys wrote:
| > PCBWay does also offer assembly services
|
| Seriously? For a tiny board like this also? Genuine question.
| kube-system wrote:
| yes, but they use a machine, they don't do it by hand.
| puzzlingcaptcha wrote:
| 01005? Oh no no no. I can barely do 0402s by hand and those are
| _2.5x_ larger.
| VTimofeenko wrote:
| 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.
| sho_hn wrote:
| With one of those mini-hotplates for reflow soldering and a LCD
| microscope it's still fairly doable.
| joemi wrote:
| 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.
| Neywiny wrote:
| Metric mm vs imperial thou. Confusing but at least
| explainable
| numpad0 wrote:
| infuriating fact: 0402 metric = 01005 imperial, 0402 imperial =
| 1005 metric. looks like this is the only semi-duplicate in
| common use.
| rts_cts wrote:
| And that's how I ended up with half a reel of 01005
| resistors...
| stavros wrote:
| Wait wait wait what? 01005 isn't metric? They switched to
| imperial for just that size? What?
| numpad0 wrote:
| I was a bit outdated with resistor sizing and I don't have
| a great sources but apparently there are:
| inch 0402, 0201, 01005, 009005, 008004, $1 mm
| 1005, 0603, 0402, 03015, 0201, 01005
|
| these sizes... and $1 is the one in your mind that shall
| not be written in inches. The "01005 imperial" is just
| 0402, so it's not going up to the metric 01005 scale or
| beyond. I think.
| uticus wrote:
| Step 1: build a robotic arm with larger components...
| Rebelgecko wrote:
| 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 wrote:
| 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.
| actinium226 wrote:
| JLCPCB also offers assembly and they're much, much cheaper,
| like an order of magnitude cheaper.
| wkat4242 wrote:
| Wow thanks!!! I've been trying to find a cheap flex pcb
| supplier but the cheapest i found was $150 for 10. They are
| way cheaper making my project viable!
| myself248 wrote:
| There's no makerspace nearby that could give you access to the
| tools and supplies to upgrade your skills?
| stavros wrote:
| This is great, well done! I don't know where I'd use this, but
| I'd definitely _want_ to use it.
| allenrb wrote:
| 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.
| Swannie wrote:
| I was thinking "how much smaller than the cheap 30mm x 25mm
| boards on AliE can you go?" ... much smaller!
|
| Very nice.
| selcuka wrote:
| FYI XIAOs are 21x18mm.
| k__ wrote:
| I just learned about XIAO boards from Grok a few days ago,
| lol.
|
| The Sense versions are pretty rad. Now I only have to add a
| battery and a touch sensor and I'm good to go.
| actinium226 wrote:
| Neat! I just sent out an order to JLCPCB for an ESP32 based
| board. I don't have a rework station or any experience with SMT
| so I decided to go for their assembly options. It's 80 per board,
| but would probably be cheaper per board if I got more than 2 (I
| also have more components on my board than you).
|
| Question about the instructions in your README, you say that once
| you're done with the top side, repeat for the bottom, but when
| you're working on the bottom side, what stops the elements on the
| top side from falling off once the heat passes through the board
| and melts the solder on that side?
| brokenmachine wrote:
| "Bottom side must be done using a rework hot air gun, not
| possible with hotplate."
|
| Basically you're hoping the bottom side doesn't get hot enough
| for everything to move or fall off.
| 4b11b4 wrote:
| Surface tension of solder in liquid state can hold the parts
| while upside down. Depends on weight of component & geometry of
| pads
| pegor wrote:
| Working on the bottom side I only used the heat gun really
| carefully on the resistors then used a soldering iron with a
| fine tip for the usb-c connector since the leads are fairly
| large.
| wkat4242 wrote:
| People that hide exploit devices in public chargers are going to
| love this one lol. Cheap, small and enough power
| GardenLetter27 wrote:
| Is it powerful enough to run a reverse proxy?
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(page generated 2025-11-21 23:02 UTC)