SERIAL DATA TRANSFER DEVICE

摘要

PROBLEM TO BE SOLVED: To reduce the number of terminals required for serial transfer. SOLUTION: Concerning the serial data transfer device for a microcomputer having a bus connecting interface with an external device, a bus connecting data terminal is not always driven but is not used at all when there is no bus cycle, and a fixed non-using period exists even during a bus cycle period without fail. By inputting/outputting serial data during the non-using period of this bus connecting data terminal, the number of terminals required for serial transfer is reduced.