Engineer Unlocks Hidden MCU Inside Semtech LR2021 LoRa Chip
Alex Beale reverse engineered the LR2021's on-board microcontroller and now runs custom firmware, enabling on-chip FFTs and mesh networking.
Alex Beale has reverse engineered the on-board microcontroller inside the Semtech LR2021 LoRa chip and demonstrated custom firmware running on it, according to hackaday.com. The work opens the chip's internal processor to code written outside Semtech's official toolchain.
The LR2021 carries a microcontroller with updatable firmware rather than a fixed, pre-programmed ASIC, which is what made the effort possible. With the internals mapped, Beale says he can now write his own firmware for the chip.
Two uses follow directly from that. Running the fast Fourier transforms behind a waterfall display can now happen on-chip, and a mesh network node can run on the chip itself rather than on a separate host processor.
Beale said large language models helped with the reverse engineering task. The tip was submitted to hackaday.com by Notbasa.
The result adds the LR2021 to a small set of radio parts whose internal processors have been opened up this way; earlier work of the same kind on WiFi and LoRa chips was aimed at unlocking software-defined radio functionality.
Quick answers
What did Alex Beale reverse engineer on the Semtech LR2021?
The chip's on-board microcontroller, which runs updatable firmware rather than being a fixed ASIC.
What can the LR2021's microcontroller now do?
Beale can write custom firmware for it, including running the FFTs for a waterfall display on-chip and running a mesh network node on the chip itself.
Did AI tools play a role in the reverse engineering?
Beale said large language models helped with the task.