This repository contains code that is used to build the platform packages as distributed through the GitHub repository:
https://github.com/mmakaay/arduino-esp32-unicore-no-mac-crc
It provides a version of the arduino-esp32 platform packages with the following changes compared to the regular distribution:
The distributed arduino-esp32 package only supports dual core ESP32 chips. If you compile firmware using that package for a single core variant of the chip, the device will end up in a boot loop, stating the error:
E (459) cpu_start: Running on single core chip, but application is built with dual core support.
E (459) cpu_start: Please enable CONFIG_FREERTOS_UNICORE option in menuconfig.
Enabling the CONFIG_FREERTOS_UNICORE build option is exacly what the build code from this repo does. This makes the resulting arduino-esp32 compatible with single core ESP32 chips.
The default MAC address for a device is read from EFUSE (MAC_FACTORY),
together with a CRC for this MAC address (MAC_FACTORY_CRC).
On some devices, a wrong CRC was burnt into EFUSE, causing the firmware to end up in a boot loop, stating the error:
Base MAC address from BLK0 of EFUSE CRC error
This firmware downgrades this error to a warning, and accepts the MAC address that was read from EFUSE as-is. This makes it possible to boot these erratic devices.