Trammell HudsonFeb 15
Ikea's Alpstuga CO2 sensor has helpfully labeled SWD pins, but the EFR32MG24 debug lock bits are set and the OTA firmware images appear to be encrypted, so I guess I'll need to erase it and start from zero with custom firmware.
Show threadTrammell Hudson
The Alpstuga will make a nice dev board with a calm four digit 7-segment display that shines through light pipes and the plastic case as a diffuser, plus my firmware might be able to use Zigbee instead of Matter over Threads.
Feb 15 at 12:11pmWeb
Show threadTrammell HudsonFeb 15
oh no maybe not! openocd says that "Device erase: Disabled" and the efm32s2_dci_device_erase does not reset it, so the Ikea Alpstuga won't accept my own firmware.
Show threadTrammell HudsonFeb 15
the EFR32MG24 data sheet says disabling device erase is irreversible and unlocking the secure debug uses a fused ECDSA-P256-SHA256 public key to sign an authentication challenge. https://docs.silabs.com/iot-security/latest/series2-secure-debug/05-debug-unlock
Show threadPoroCYonFeb 15
@th ah, yeah, their new 2-seris actually has serious hardware security features. good luck with the attacks
Show threadRick AltherrFeb 15
@th oh wow. Someone actually built a robust design for this.
Show threadTrammell HudsonFeb 15
@mxshift yeah, wearing my defensive security hat I'm impressed with the design of this debug unlock in such a small microcontroller. don't know how well it is implemented in silicon, but it is sufficient for me to look for other side projects.
Show thread23n27Feb 15
@th @mxshift I recently looked into the Series 2 Gecko chips for work and the whole security architecture seems pretty neat. Alas, it comes with Silabs-grade docs (though the security docs are actually decent) and tooling. Maybe things will get better after the TI acquisition.
Show threadGraham Sutherland / PolynomialFeb 15
@th time to stick a fast FET across the power rail, then? :P
Show threadWilliam D. JonesFeb 15
@gsuberland @th Glitch attack or something more specific?
Show threadGraham Sutherland / PolynomialFeb 15
@cr1901 @th glitch attack.
Show threadFritz AdalisFeb 15
@th
Well that sucks.
Show threadOwOdayFeb 15
@th does it have XiP?
Show threadFelixFeb 15
@th 👀 sounds like a really cool project!