The Controller Area Network (CAN) bus protocol defines a fault-tolerant multi-master serial protocol. Originally it was intended for use in vehicles, but the robustness of the CAN protocol has made it a popular choice in a wide range of control applications, also in the radiation environments seen in space applications or high-energy physics experiments. Electronics designed for radiation environments often feature an FPGA, and employ Triple Modular Redundancy (TMR) to achieve radiation tolerance. There are several varieties of TMR, and the best choice is highly technology-dependent. We are presenting a new open-source CAN controller written in VHDL for FPGAs. The controller is highly configurable, but when used in a radiation environment, it features TMR techniques specifically tailored for Xilinx FPGAs.