LCD display circuit design

HY12864 is a 128×64 dot matrix LCD module that uses two HD61202s as column drivers and one HD61203 as a row driver. The chip structure is shown in the figure. HY12864 has a simple but powerful instruction set, and the data transmission with the microcontroller adopts 8-bit parallel transmission. The character library to be used is stored in the on-chip Flash. By calling the LCD character display program, Chinese and English characters can be displayed.

Figure HY12864 logic function and pin diagram

In HY12864, the ADO of both HD61202s are connected to a high level, and RST is also connected to a high level, so there is no need to consider the role of these two pins when using HY12864. CSA is connected to /CS1 of HD61202 (1); /CSB is connected to CS1 of HD61202 (2), so the CSA, CSB selection combination signal is CSA, CSB = 01 selection (1), CSA, CSB = 10 selection (2).

The addresses and functions corresponding to ear Y128.4 are shown in Table 1 and Table 2 respectively.

Table 1 LCD hardware address

The key connections are:

RS = Addr0;

RW = Addr1;

E = EDPL = the NAND of the R and W lines of the CPU;

CS1＝CSIDPL when P2＝1001xxxx CS1 is 0; CS2＝CS2DPL when P2＝1010xxxx CS2 is 0.

Table 2 LCD pins and functions