Show HN: F32 – An Extremely Small ESP32 Board(github.com)
299 pointsby pegor4 days ago16 comments
  • jacquesm3 days ago
    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.
    • atemerev3 days ago
      These cables can be bought for like $200 mostly legally.
  • tmpfs4 days ago
    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!
    • pegor4 days ago
      Thank you! I agree, antenna definitely needs some improvement.
      • wkat42422 days ago
        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.
  • anyg3 days ago
    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!!
    • margalabargala3 days ago
      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/

      • dotancohen3 days ago
        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.

        • margalabargala3 days ago
          It only has 14 pins, 3 of which are 5v, 3.3v, and ground, so slight exaggeration :-) point taken though
      • lelanthran2 days ago
        These are nifty. I've used them in production, but if you want to make used of the charger it's difficult.
      • sho_hn3 days ago
        These are quite lovely. Ceramic SMD antennas are awesome.
    • pegor3 days ago
      Definitely would be more functional with more of the GPIOs exposed.
      • forsalebypwner3 days ago
        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.
        • stavros2 days ago
          I don't know, I see enough space for four GPIOs there. Not holes, obviously, but pads should be very workable.
        • imtringued2 days ago
          It could be even smaller without that USB C port and have more GPIO pads.
    • PunchyHamster3 days ago
      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

    • venusenvy472 days ago
      Can anyone suggest a small module that supports 5 GHz WiFi?
  • actinium2263 days ago
    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?

    • pegor3 days ago
      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.
    • 4b11b43 days ago
      Surface tension of solder in liquid state can hold the parts while upside down. Depends on weight of component & geometry of pads
    • brokenmachine3 days ago
      "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.

  • Rebelgecko3 days ago
    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?
    • dotancohen3 days ago
      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.
      • actinium2263 days ago
        JLCPCB also offers assembly and they're much, much cheaper, like an order of magnitude cheaper.
        • wkat42422 days ago
          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!
    • myself2482 days ago
      There's no makerspace nearby that could give you access to the tools and supplies to upgrade your skills?
  • stavros3 days ago
    This is great, well done! I don't know where I'd use this, but I'd definitely want to use it.
  • Swannie3 days ago
    I was thinking "how much smaller than the cheap 30mm x 25mm boards on AliE can you go?" ... much smaller!

    Very nice.

    • selcuka2 days ago
      FYI XIAOs are 21x18mm.
      • k__2 days ago
        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.

  • GardenLetter272 days ago
    Is it powerful enough to run a reverse proxy?
  • wkat42422 days ago
    People that hide exploit devices in public chargers are going to love this one lol. Cheap, small and enough power
  • allenrb3 days ago
    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.

  • NuclearPM3 days ago
    > This can be seen in my highly necessary depiction below.

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

    • unwind2 days ago
      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. :)

      • nhecker2 days ago
        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)

    • pegor3 days ago
      Thanks for checking it out!
  • puzzlingcaptcha3 days ago
    01005? Oh no no no. I can barely do 0402s by hand and those are _2.5x_ larger.
    • VTimofeenko3 days ago
      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.

    • joemi3 days ago
      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.

      • Neywiny3 days ago
        Metric mm vs imperial thou. Confusing but at least explainable
    • sho_hn3 days ago
      With one of those mini-hotplates for reflow soldering and a LCD microscope it's still fairly doable.
    • uticus2 days ago
      Step 1: build a robotic arm with larger components...
    • numpad03 days ago
      infuriating fact: 0402 metric = 01005 imperial, 0402 imperial = 1005 metric. looks like this is the only semi-duplicate in common use.
      • rts_cts3 days ago
        And that's how I ended up with half a reel of 01005 resistors...
      • stavros2 days ago
        Wait wait wait what? 01005 isn't metric? They switched to imperial for just that size? What?
        • numpad02 days ago
          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.
  • ingen0s3 days ago
    Nice work, kudos!
  • Gys3 days ago
    > PCBWay does also offer assembly services

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

    • kube-system3 days ago
      yes, but they use a machine, they don't do it by hand.
  • Will-Reppeto3 days ago
    [flagged]
  • jason-richar153 days ago
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