Design and realization of general matrix keyboard based on STM32

The matrix keyboard is taken as the basic input device of MCU or embedded systems. For traditional matrix keyboard, the number of interface signal lines connected to the MCU will rapidly increase with the rise of the number of keys. And it uses row scanning to get key values in software. But this situation is not suitable for MCU (Micro-programmed Control Unit) or embedded chips which have limited hardware resources, especially in the application with human-computer interaction. A novel scheme of general matrix keyboard based on set mapping theory is proposed in this paper. It uses the combination of external interrupt and priority encoder to overcome the problems in the traditional matrix keyboard. The design details of the hardware and software are presented. Through the application in the interactive display board system, it shows that the proposed scheme is feasible and effective.