An open source drop-in replacement for the legacy ESP8266 bootloader.
The ESP8266 NONOS SDK, as well as RTOS SDK v1.x/v2.x, rely on the legacy bootloader provided as a binary blob.
Unfortunately, it has a bug that prevents OTA updates when the 8MB or 16MB flash map is used. This repository provides
an alternative open source bootloader that fixes this issue and can be used as a drop-in replacement for boot_v1.7.bin
bootloader, without the need to change any user code.
The code is based on rBoot by Richard A Burton, with modifications to make it compatible with the standard OTA API used in NONOS SDK and RTOS SDK v1.x/v2.x. All extra rBoot features have been removed (since they wouldn't be compatible with the API anyway). Refer to the original repository for information about rBoot. Also check out the following resources which were useful:
The only change in behavior compared to boot_v1.7.bin is a different message printed during boot, and a different UART
baud rate (115200 rather than 74880). However, the baud rate is can be changed by editing rboot.h. If for
some reason you require even greater compatibility with the original bootloader, check out
Fixboot.
Note: NONOS SDK and RTOS SDK v1.x/v2.x are deprecated. You should use RTOS SDK v3.x for new projects.
The compiled binary is available on the Releases page. If you want to build
it yourself, you'll need the ESP8266 toolchain (version 4.8.5 is recommended). On Windows, a compatibility layer such as
MSYS2 is required. For installation instructions, refer to
RTOS SDK docs.
Make sure xtensa-lx106-elf/bin is added to the PATH environment variable.
Additionally, you will need Esptool2. Place the Esptool2 and MBoot directories
in the same parent directory. You can use make to compile Esptool2 (on Windows use the MINGW64 shell or compile it
with Visual Studio).
Once you have the toolchain and Esptool2 installed, run make to build MBoot (on Windows use the MSYS2 shell).
When flashing the ESP8266, simply use mboot.bin instead of boot_v1.7.bin. The regular NONOS SDK or RTOS SDK
v1.x/v2.x OTA update process should work without issues.
This project is released under the MIT license. It is based on rBoot by Richard A Burton, which is released under the MIT license.