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.