SERIAL DATA TRANSFER DEVICE

PURPOSE:To reduce the overhead of a central processing unit even at the time of complicated communication by easily realizing the chip select required for serial data transfer. CONSTITUTION:A chip select signal CS (inverted) is driven, and a counter 22 starts to count the delay signal obtained based on a clock signal 9 at the time of the start of serial data transfer, and a stop signal 10 is outputted to terminate the transfer when the counted value reaches the set value of a register 23. Since the chip select signal CS (inverted) is driven from the start of transfer to the generation of the stop signal 10 in this manner, a device to which data should be transferred can keep the write operation.