ROS Software Maintainer: ROBOTIS
OpenCR means Open-source Control Module for ROS. OpenCR is developed for ROS embedded systems to provide completely open-source hardware and software. Everything about the board; Schematics, PCB Gerber, BOM and the firmware source code for the TurtleBot3 and OP3 are free to distribute under open-source licenses for users and the ROS community. The STM32F7 series chip inside the OpenCR board is based on a very powerful ARM Cortex-M7 with floating point unit. The development environment for OpenCR is wide open from Arduino IDE and Scratch for young students to traditional firmware development for the expert.
ROS Wiki related to OpenCR
References related to OpenCR