Micro-controller unit for selectively accessing an internal memory or an external extended memory using a read/write terminal

摘要

A micro-controller unit (MCU) selectively accesses one of an external extended memory and an internal memory in response to a signal on a read/write terminal instead of an additional terminal. The micro- controller unit includes an external memory control block, an external timing control block, and the internal memory, and additionally includes a reset detection circuit, a memory access clock generation circuit and a latch. The reset detection circuit receives an external reset signal for initializing the MCU and an external clock, and detects whether the micro- controller unit is reset. The memory access clock generation circuit receives an output signal from the reset detection circuit and generates a memory access clock signal to selectively access one of the internal memory and the external extended memory. The latch receives the external reset signal, the memory access clock signal and a memory interface signal applied to the read/write terminal for applying a memory access selection signal to the external memory control block, the external timing control block and the internal memory, whereby a memory selection is performed by the reset signal and the memory interface signal.