Method of interfacing single chip microcomputer with graphic liquid crystal display

　　Dot-matrix flat-panel graphic LCDs are widely used in various portable products. For different manufacturers' products and different application purposes, there are many varieties of core LCD display controllers. For example, Hitachi's MDF series uses integrated chips such as HD44780, HD61830, HD61830, HD61202, and T6963C as LCD display controllers. Various control chips differ in control circuit logic, instructions, index parameters, etc. However, for flat-panel dot-matrix graphic LCDs that already have control circuits, users do not need to care about the integrated chip of their control core. For example, the MDF series products of Hitachi mentioned above only need to clarify a few signals of the control circuit to conveniently use it for development and research. Regardless of the model of the product, the signals are basically the same. This section combines the MDF5001 160×128 dot-matrix graphic LCD to introduce its interface with the 51 single-chip microcomputer, and provides software for displaying characters and Chinese characters.

1. Introduction to Hitachi MDF5001 160×128 dot matrix graphic LCD display
　　
　　As shown in Figure 1, this product uses T6963C as the display controller. The control circuit has 64 KB display buffer and 128 character dot matrix ROM. It has two working modes: character and graphic. Both can be set as the current working mode at the same time.

　　
　　1. Control signal
　　
　　DO~D7: 8-bit data line, used to exchange information with the display.
　　
　　WR: Write signal, write command and display data.
　　
　　RD: Read signal, read controller status and signal.
　　
　　CE: Chip select signal.
　　
　　C/D: When writing, high level indicates write command, low level indicates write data; when reading/writing, high level indicates read controller status, low level indicates read data.
　　
　　HALT: Pause LCD operation.
　　
　　RESET: Reset LCD operation.
　　
　　2. Control code
　　
　　The display control setting code is listed in the following table.

　　3. Status word of the display
　　
　　When the control signal of the LCD display is RD: low, WR: high, CF: low, C/D: high, the data line indicates the working status of the display at that time.

2. Interface and application of display and 8031 ​​single-chip computer system
　　
　　As shown in the figure below, under the control of 8031, the control port CONP address is 8000H. The data port address DATP is 8001H. In the initialization program, the display is set to work in text and graphics at the same time. The LCP subroutine is the display status detection program. Once the display is ready for writing, the subroutine is exited.