Liquid crystal displays 20 characters2 lines COG module RCM2072R The RCM2072R is a reflective TN type liquid crystal module with a built-in controller / driver LSI and a display capacity of 20 characters2 lines. Applications Printers, copiers, facsimiles, etc. Features 1) Wide viewing angle and high contrast. 2) 57 dot character matrix with cursor. 3) Interfaces with 4-bit or 8-bit MPUs. 4) Displays up to 237 characters and special symbols 5) Custom character patterns are displayed with the character RAM. 6) Abundant instruction set including clear display, cursor on / off, and character blinking. 7) Compact and lightweight for easy assembly to the host instrument. 8) Operable on single 5V power supply. 9) Low power consumption. External dimensions (Units: mm) 29 Liquid crystal displays Block diagram Pin assignments Power supply example 30 RCM2072R Liquid crystal displays RCM2072R FAbsolute maximum ratings (Ta = 25_C) FElectrical characteristics (VDD = 5.0 ± 5%, Ta = 25_C) FOptical characteristics (Ta = 25_C) When viewing from below 31 Liquid crystal displays Pin functions Note: In order to be able to interface with 4-bit or 8-bit MPUs, the module supports data transfer with two transmissions of 4 bits at a time or one transmission of 8 bits at once. (1) When the interface data length is 4 bits, data is transferred between the MPU along DB4 through DB7 buses and DB0 through DB3 buses are not used. Data transferral is completed after two transfers of 4 bit data. First the upper nibble (contents of DB4 through DB7 during 8-bit interfacing) is transferred and then the lower nibble (contents of DB0 through DB3 during 8-bit interfacing) is transferred. Check for busy flag occurs after the second 4-bit data (one instruction) is transferred. At that time, the busy flag and address counter data is also output in two 4-bit increments. (2) When the interface data length is 8 bits, the data DB0 through DB7 is transferred along the eight data buses. 32 RCM2072R Liquid crystal displays RCM2072R Timing chart (1) Writing 33 Liquid crystal displays (2) 34 Reading RCM2072R Liquid crystal displays RCM2072R Instructions (Example) When fosc = 270kHz 40µs 250 270 = 37µs 35 Liquid crystal displays Character code and corresponding character pattern 36 RCM2072R Liquid crystal displays RCM2072R FReset function When you turn on the power supply, the module automatically returns to its initial (reset) settings. At the initial settings, the busy flag (BF) becomes “1.” The busy status last 10 ms from when VDD reaches 4.5V. At the initial settings, following instructions are carried out. (1) Clear display (2) Function set 8-bit interface data length (DL = 1) Two line display (N = 1) SEG signal transfer direction SEG1SEG50SEG51SEG100 (SD1 = 0, SD2 = 0) COM signal transfer direction COM1COM16 (CD = 0) (3) Display on / off control Display off (D = 0) Cursor off (C = 0) Blinking off (B = 0) (4) Entry mode set +1 (increment) (I / D = 1) No shift (S = 0) ∗ The internal reset circuit may not operate properly due to conditions with the power supply. If this is the case, use the appropriate instruction to reset the settings. FOperation notes (1) Handling precautions S Protect the module from strong shocks as they can cause damage or defective operation. S The polarizing plate on the surface of the module is soft and can easily be scratched. Wipe away dirt and dust using an alcohol-based cleanser. S If the liquid crystal panel is damaged and liquid crystal contacts your clothing or body, wash immediately with soap and water. S If the module is to be used for long periods subjected to direct sunlight, employ a filter to block the ultraviolet rays. S Do not use the module in areas of high temperature or high humidity. Do not use the module in locations exposed to direct sunlight or fluorescent light. S A protective film (polyethylene) is pasted over ROHM liquid crystal modules to protect the panel surfaces. When peeling this film off, be sure to peel as slow as possible in order to minimize the generation of static electricity. (2) Precautions during operation S Do not connect or disconnect the module while the power supply is turned on. S Input the input signal after the module power supply is turned on. When turning it off, turn off the input signal first. Otherwise the IC may be damaged by the latch-up phenomenon. 37