Show HN: F32 – An Extremely Small ESP32 Board
(github.com)297 points by pegor 3 days ago
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.
297 points by pegor 3 days ago
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.
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!!
The XIAO series of ESP32s is exactly that.
They are 4x the size though, almost exactly double in both length and width.
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.
It only has 14 pins, 3 of which are 5v, 3.3v, and ground, so slight exaggeration :-) point taken though
These are nifty. I've used them in production, but if you want to make used of the charger it's difficult.
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.
Can anyone suggest a small module that supports 5 GHz WiFi?
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
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?
"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.
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?
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.
JLCPCB also offers assembly and they're much, much cheaper, like an order of magnitude cheaper.
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. :)
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)
01005? Oh no no no. I can barely do 0402s by hand and those are _2.5x_ larger.
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.
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.
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
yes, but they use a machine, they don't do it by hand.
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.