Unveiling secrets of the ESP32: creating an open-source MAC layer
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Re: Unveiling secrets of the ESP32: creating an open-source MAC layer
#2Headline should read "MAC" layer like it does in the article, not "Mac" layer. Two very different things :)
Re: Unveiling secrets of the ESP32: creating an open-source MAC layer
#3The 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.
Re: Unveiling secrets of the ESP32: creating an open-source MAC layer
#4Headline should read "MAC" layer like it does in the article, not "Mac" layer. Two very different things :)
Oops, my bad, copy-pasted it incorrectly; fixed now
Re: Unveiling secrets of the ESP32: creating an open-source MAC layer
#5I 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?
Re: Unveiling secrets of the ESP32: creating an open-source MAC layer
#6I 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?
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.
Re: Unveiling secrets of the ESP32: creating an open-source MAC layer
#7The 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.
ESP32C3 has great Rust support too.
Re: Unveiling secrets of the ESP32: creating an open-source MAC layer
#8Wouldn'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.
Re: Unveiling secrets of the ESP32: creating an open-source MAC layer
#9Wouldn'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.
> 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...
Re: Unveiling secrets of the ESP32: creating an open-source MAC layer
#10The 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.