The dot-matrix liquid crystal display has the advantages of displaying complicated characters and graphics, and having various display screen sizes, and has wide application prospects in industrial instruments and electronic equipment such as smart instruments and meters. ST's mPSD series of single-chip microcomputers are gradually applied to control areas with high functional requirements due to their powerful interface, large storage capacity and convenient system development. The rich peripheral interface and large-capacity memory of its programmable logic must be configured with PSDSOft Express software, unlike the traditional 51-series microcontroller development. Through the application of mPSD3334D in actual projects, this paper focuses on its characteristics and its interface with the liquid crystal module GXM12232-1 with built-in SED1520 liquid crystal controller, and gives the pin configuration of mPSD3334D and the flow control chart of GXM12232-1 display. . mPSD3334D microcontroller The mPSD33xx family of microcontrollers is a high-performance embedded controller that integrates an 8051 microcontroller, flexible memory structure, programmable logic and a rich peripheral interface. The chip consists of two modules: MCU and PSD. The difference between the different types of MCUs in this series is mainly reflected in the difference of the memory space and the supply voltage of the MCU module and the PSD module. The mPSD3334D has 256KB of Flash and 8KB of SRAM. The MCU module is powered by 3.3V and the PSD module is powered by 5.5V. Compared with the traditional 8032 MCU, except for the clock characteristics and the controllable instruction prefetch and jump cache characteristics, the other differences are mainly as follows: 1. Flexible expansion of peripheral interface functions. The PA, PB, PC, and PD ports are multi-function multiplexed ports. The settings of the corresponding registers can be flexibly switched according to system requirements. The port supply voltage is different from the MCU module voltage, which can be easily interfaced with different peripheral power supply voltage devices to reduce the system voltage conversion design. 2. High-performance JTAG debugging and downloading functions to facilitate product development and production. The SED1520 is a dot-matrix LCD driver that can be directly connected to an 8-bit CPU for ease of use. The SED1520 is a combination of a driver and a controller. It is a built-in controller and is widely used in the display of small-scale LCD modules. The main features of the SED1520 drive are: 1. The internal display RAM capacity is 2560b. Each of its data controls the on and off state of a point on the LCD screen. "1" means bright, and "0" means dark. 2. With 16 row drivers and 61 column drivers, it can be easily combined with SED1521 for single column expansion. 3. The bus speed can reach 10M, and the display duty ratio is 1/16 or 1/32. The SED1520 and SED1521 have different combinations of rows and columns depending on the size of the LCD screen. For example, the screen size is 141 & TImes; 16, the liquid crystal module with a duty ratio of 1/16 is expanded by SED1521. When the number of LCD screens exceeds the row driving capability of the single-chip SED1520, the master-slave SED1520 can be used for line expansion. As shown in Figure 1. The internal system block diagram of the SED1520 driver used in the GXM12232-1 liquid crystal module described in this article is shown in Figure 1. Two SED1520s with master-slave structure are used to control the left and right half screen display of the display screen. Figure 1 is extended with a master-slave SED 1520 The SED1520 instruction system is relatively simple. There are 13 instructions. Except for the read status command and the read RAM data command, all other instructions are write operations, and the read and write instructions are single-byte instructions. When each instruction is sent, the controller status detection must be performed. The meaning of the status byte is as follows: D7: 1/0, the module is busy/ready; D5: 1/0, the module displays off/on; D4: 1/0, module reset / normal; D3-D0: Not used In the use of instructions, the key is to distinguish the relationship between display line and column settings and display page settings. The single-chip SED1520 can drive 61&TImes; 16 LCD screens, and its internal display RAM acts as a display page for every 8 bits of COM0, so the module used in this article can display 4 pages. LCD module with mPSD3334D The SED1520 driver is designed with 80-CPU and 68-CPU interface timing. The GXM12232-1 module has different pin connections when using different control timings. This design uses the 68-CPU control timing when using this module. The PA port is connected to the data line of the liquid crystal module, PB4 and PB3 are respectively connected to the liquid crystal module pins E1 and E2, the PB2 is connected to the module RW, and the PB1 is connected to the module data command control pin A0. The PA of the mPSD3334D MCU is a multi-function multiplexer port, and the PB port has a programmable logic output function. In this paper, in order to facilitate program migration and interface timing requirements, the PA port is set to the peripheral device mode; PB4 and PB3 are set to CPLD output external chip select, active high mode, named LCD_E2, LCD_E1; PB2, PB1 are set to CPLD output Combinatorial mode, named LCD_RW, LCD_A0. The pin definition of the peripheral mode of the PA port must be completed using the PSDSOFt_Express software, and the pin operation mode cannot be changed while the program is running. 5G Integrated Lithium Ion Battery 5G Integrated Battery,51.2V Battery System,Integrated Lithium Ion Battery,Backup Lithium Ion Battery Wolong Electric Group Zhejiang Dengta Power Source Co.,Ltd , https://www.wldtbattery.com