[HN Gopher] Unveiling secrets of the ESP32: creating an open-sou...
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Unveiling secrets of the ESP32: creating an open-source MAC layer
Author : redfast00
Score : 44 points
Date : 2023-12-06 21:50 UTC (1 hours ago)
(HTM) web link (zeus.ugent.be)
(TXT) w3m dump (zeus.ugent.be)
| dgreensp wrote:
| Headline should read "MAC" layer like it does in the article, not
| "Mac" layer. Two very different things :)
| redfast00 wrote:
| Oops, my bad, copy-pasted it incorrectly; fixed now
| Max-q wrote:
| The article claims that the ESP32 costs $5. The reality is around
| half of that for the MCU, and around $3 for pre certified modules
| including crystal, PCB antenna or UF-L connector. So it's really
| affordable.
|
| Espressif has also launched a new ESP32C3 based on RISC-V, with
| modules priced at around $2.
| rwaksmunski wrote:
| ESP32C3 has great Rust support too.
| icpmacdo wrote:
| I can attest to the challenges of the section on Dynamic analysis
| on real hardware and the struggles of attenuating signal
| interference on the ESP.
|
| Anyone have a recommendation on conducting fabric for RF
| isolation as briefly mentioned in the article or resources on the
| subject of rf isolation/Faraday cages for microcontrollers?
| redfast00 wrote:
| As part of the NLNet grant, I will build an affordable Faraday
| cage; I'll post the BOM, assembly process and a test report in
| a separate blog post.
| jcalvinowens wrote:
| Based only on my own anecdotal experience... I think the hole
| the cables go through is the biggest problem in OPs setup. I'd
| solder the shields to the cage circumferentially around the
| hole. Shielded USB cables aren't too hard to find, it wouldn't
| be as good as something optical but it's a lot easier.
| calamari4065 wrote:
| Wouldn't this invalidate the FCC certification on the prebuilt
| modules? You'd have to get certified with this firmware to ensure
| you aren't violating transmission power requirements.
|
| Admittedly, this is a non-issue for hobby scale projects, but is
| potentially a blocker for commercial applications.
|
| I wouldn't say it's necessarily a bad thing, but worth
| discussion.
| throw0101b wrote:
| > _Wouldn 't this invalidate the FCC certification on the
| prebuilt modules?_
|
| MAC is at OSI Layer 2. FCC concerns about radio power occur at
| the PHY layer, OSI Layer 1:
|
| > _On the ESP32, the PHY layer is implemented in hardware; most
| of the MAC layer is implemented in the proprietary blob. One
| notable exception to this separation is sending acknowlegement
| frame: if a device receives a frame, it should send a packet
| back to acknowledge that this packet was received correctly.
| This ACK packet needs to be sent within ~10 microseconds; it
| would be hard to get this timing correct in software._
|
| *
| https://pics.zeus.gent/vYXyQm2t9pJCzpDdWFvq9oWR2DACoUJoTsYf8...
| WatchDog wrote:
| The section on trying to attenuate outside wifi signals
| interested me.
|
| There is a bunch of hand wavy information on building faraday
| cages online, some people suggesting to utilize a microwave oven,
| since they operate at the same frequency.
|
| There are even wifi faraday cages for sale on amazon.
|
| However I can't really find much actual benchmark data online
| about how well these various approaches actually attenuate
| signals.
| rkfjrjrkfnrkd wrote:
| This is very interesting. I'm keen to get involved but, while I'm
| very experienced with ESP32, I don't have experience with this
| type of reverse engineering.
|
| How long did it take you to get the environment and tools set up,
| so you could start digging in?
|
| Is time or money a more valuable investment at this stage? If
| it's not too forward, how much would be useful to your
| organisation? (I can email if preferred.)
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(page generated 2023-12-06 23:00 UTC)