Datasheet HD44780U (LCD-II) (Hitachi) - 8

HD44780U Pin Functions No. of Device Signal Lines I/O Interfaced with Function
RS 1 I MPU Selects registers. 0: Instruction register (for write) Busy flag: address counter (for read) 1: Data register (for write and read) R/W 1 I MPU Selects read or write. 0: Write 1: Read E 1 I MPU Starts data read/write. DB4 to DB7 4 I/O MPU Four high order bidirectional tristate data bus pins. Used for data transfer and receive between the MPU and the HD44780U. DB7 can be used as a busy flag. DB0 to DB3 4 I/O MPU Four low order bidirectional tristate data bus pins. Used for data transfer and receive between the MPU and the HD44780U. These pins are not used during 4-bit operation. CL1 1 O Extension driver Clock to latch serial data D sent to the extension driver CL2 1 O Extension driver Clock to shift serial data D M 1 O Extension driver Switch signal for converting the liquid crystal drive waveform to AC D 1 O Extension driver Character pattern data corresponding to each segment signal COM1 to COM16 16 O LCD Common signals that are not used are changed to non-selection waveforms. COM9 to COM16 are non-selection waveforms at 1/8 duty factor and COM12 to COM16 are non-selection waveforms at 1/11 duty factor. SEG1 to SEG40 40 O LCD Segment signals V1 to V5 5 — Power supply Power supply for LCD drive V –V5 = 11 V (max) CC V , GND 2 — Power supply V : 2.7V to 5.5V, GND: 0V CC CC OSC1, OSC2 2 — Oscillation When crystal oscillation is performed, a resistor resistor clock must be connected externally. When the pin input is an external clock, it must be input to OSC1. 8 Document Outline Description Features Ordering Information HD44780U Block Diagram HD44780U Pin Arrangement (FP-80B) HD44780U Pin Arrangement (TFP-80F) HD44780U Pad Arrangement HD44780U Pad Location Coordinates Pin Functions Function Description Interfacing to the MPU Reset Function Instructions Instruction Description Interfacing the HD44780U Power Supply for Liquid Crystal Display Drive Relationship between Oscillation Frequency and Liquid Crystal Display Frame Frequency Instruction and Display Correspondence Initializing by Instruction Absolute Maximum Ratings DC Characteristics AC Characteristics Bus Timing Characteristics Interface Timing Characteristics with External Driver Power Supply Conditions Using Internal Reset Circuit DC Characteristics AC Characteristics Bus Timing Characteristics Interface Timing Characteristics with External Driver Power Supply Conditions Using Internal Reset Circuit Electrical Characteristics Notes Load Circuits Timing Characteristics