LCD LCD Key scan control circuit in microcontroller

摘要

The present invention relates to an LCD key scan control circuit of a microcontroller. The LCD key scan control circuit according to the present invention includes a display RAM for storing segment data of an LCD, a ring counter for automatically generating keystroke data, and a ring counter for generating part of segment data stored in the display RAM, A multiplexer for multiplexing and outputting keystroke data generated by the counter, a multiplexer for receiving another part of the segment data stored in the display RAM and outputting the multiplexed data to segment dedicated ports, receiving output data of the multiplexer, And a key scan input circuit for receiving key scan input data according to key strobe data output through the segment and the key strobe port when a predetermined external key is pressed, thereby generating an interrupt . Therefore, since the key strobe data is automatically generated by the ring counter, the LCD key scan control circuit according to the present invention does not need to repeatedly write key strobe data for a plurality of key scans, Since the input circuit includes a latch for latching the key scan input data, the key check can be performed by reading the key scan data stored in the latch even if the external key is not pressed during the key check in the interrupt processing routine .