Quote:
Originally Posted by wd40addict
If I understand correctly you've used a different LCD, do they all have a common interface?
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All the ones I have encountered certainly did. They had an LCD controller in a square surface-mount package with leads on all 4 sides. The interface consists of 8 data lines (with the ability to use just 4 of them), an address line (which selects whether you are talking to the display register or the control register), read/write and a strobe. These, power and ground and an input for a contrast control pot (some modules will give a perfectly readable display with this pin left unconnected, but do not rely on this behaviour) are brought out to a row of 14 pads on the PCB. There may be additional connections for LED backlighting. Compact units also exist with a two-row header for a ribbon cable, but this carries the same electrical signals and even the pin order within the ribbon cable comes out the same as the larger modules' single row.
Data is sent to the display register as ASCII character codes, either 8 or 4 bits at a time. The control register accepts instructions for various functions (reset, position select, user-defined characters .....) The instruction to select 4- or 8-bit operation can be sent using only a 4-bit connection.