The visual navigation system for a mobile patrol robot using image processing by FPGA and real-time device driver is presented. The CMOS image sensor and the stepper motor driver ICs are connected to external I/O ports of the FPGA. The image processing and motor drive circuits are implemented into the FPGA device together with state machine and FIFO memory buffer to adjust timing for pixel data transmission. The real-time device driver couples the flexible hardware circuits with software applications for the robot vision.