LCD Kisscan Control Circuit of Microcontroller

摘要

The present invention relates to an LCD kisscan control circuit of a microcontroller. The LCD kisscan 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, a portion of segment data stored in the display RAM in response to a control signal, A mux for multiplexing and outputting the keystrobe data generated by the counter, and receiving another part of the segment data stored in the display RAM and outputting the segment to the dedicated ports, and receiving the output data of the mux, the segment and the keystroke combined port And a kisscan input circuit that generates an interrupt when a predetermined external key is pressed and receives kisscan input data according to the keystroke data output through the segment and keystrobe combined port when a predetermined external key is pressed. It features. Therefore, in the LCD kisscan control circuit according to the present invention, since the keystroke data is automatically generated by the ring counter, it is not necessary to repeatedly write the keystroke data for a plurality of kisscans. Since the input circuit includes a latch for latching the kisscan input data, the key check can be performed by reading the kisscan data stored in the latch even when an external key is not pressed during the key check in the interrupt processing routine. .