Datasheet for the HJ1602A, a 16x2 character LCD module, provided as a 320 KB PDF. It covers the module dimensions, pin assignment, electrical characteristics and the instruction set for its character controller. For servicing, the pinout helps verify supply, contrast adjustment and backlight current, while timing diagrams help diagnose garbled characters caused by a faulty interface. Because many 1602-class displays look alike, check the part marking on the module back before relying on mechanical or backlight details from this sheet.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @datasheet. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.