Bootloader Firmware
The default bootloader for the CDL-689 is based on OpenBLT and modified to support RS-485 communication on an STM32F411 microcontroller. The bootloader code and instructions for entering bootloader mode can be found here:
https://github.com/CanopyDL/cdl689-boot
Application Firmware
The CDL-689 comes with a simple application firmware that can be tailored to your specific needs. The application firmware can be found here:
https://github.com/CanopyDL/cdl689-app
This application is based on the STM32Cube IDE, a modified version of a ModBus library (https://github.com/smarmengol/Modbus-Master-Slave-for-Arduino), openBLT, and FreeRTOS.