Noise-tolerant data communication system

摘要

This invention offers a data communication system that can perform data communication and detection of a data read-in request signal while reducing the number of communication lines to three, and is tolerant of noise. The data communication between a microcomputer and a key scan IC and the detection of the data read-in request signal are performed through a control line, a clock line and a data line. The data communication system is provided with a data line control circuit that controls the data line so that outputting of the data read-in signal RDRQ to the data line is disabled when first command data is inputted to the key scan IC through the data line, and that the outputting of the data read-in request signal RDRQ to the data line is enabled when second command data is inputted from the microcomputer to the key scan IC through the data line.