| Symbol | Level | IN /OUT | Function |
| Vss | | | OV | Earth |
| VDD | | | 5Ov | Power supply voltage |
| VIN Vs | | | 3.0~5.OV (VDD-V5) | The Vs pin is for the liquid crystal contrast adjustment should be kept within the range VDD>V5>Vss. |
| GND | | | Frame GND |
| RS | H/L | IN | Register selection signal. O: Instruction register (writing) Busy flag, address counter (reading) 1 : Data register (reading / writing) |
| R/W | H/L | lN | Reading (R) and writing (W) selection signal. O: Writing MPU- LCD module 1: Reading MPUFLCD module |
| E | HH/L | lN | Data reading and writing start signal. |
| DBO 2 DB3 | H/L | IN /OUT | The lower 4 line data buses are 3-state bi-directional. They are not used during 4-bit operation and must be fixed to GND. |
| DB4 2 DB7 | H/L | IN /OUT | The upper 4 line data buses are 3-state bi-directional. DB7 can also be used as a busy flag. |
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