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HY-240128M-201 liquid crystal display module and its application

Print View , by: iSee ,Total views: 9 ,Word Count: 2446 ,Date: Fri, 5 Jun 2009 Time: 2:19 AM

Introduction

display and content in accordance with the different instrumentation used in the liquid crystal display module and point pen above two types of formation. The former can be used to show that a finite number of simple symbols, control is relatively simple. The latter can be divided into two types: character and graphics LCD module LCD module. Dot-matrix liquid crystal display module to display information, and can display characters, Chinese characters, but also can display graphics and curves, and easy to interface with the microprocessor, so often used in machinery and equipment and automatic production line control display devices in the operating parameters, or graphical display of equipment and production lines process.

In this paper, the practical application point of view, in a brief introduction T6963C controller based on the HY-240128M-201 dot-matrix graphic liquid crystal display module, after the composition and working principle, this paragraph focuses on the use of liquid crystal display module method of ATmega8535-based single-chip design with hardware / software design ideas and points.

HY-240128M-201 liquid crystal display module and its application

Figure 1 HY-240128M-201 single-chip interface circuitry and ATmega8535

About LCM

HY-240128M-201 isBeijing (BALDWIN) Electronic Technology Co., Ltd. launched the 240 × 128 dot-matrix liquid crystal display module. Although the liquid crystal display module principle of the internal circuit more complicated, but stay only a display module with an external communication interface, LCM can be displayed through this interface to receive commands and data, and in accordance with the requirements of the command and data display; external circuit through the interface read out the display module and display the work of state data. LCM users only need to understand the function of the external pin and the module can display the principle. This LCM provides two interfaces: parallel and serial data transfer interface command. 8 way parallel transmission, a transmission that is 8-bit command or data; and the use of serial transmission data bus 4. In order to make liquid crystal display modules are more stable, in practice often means the use of parallel transmission.

HY-240128M-201 liquid crystal display module by a LCM controller T6963C, 2 chip line drive T6A40, 3 chip drive out T6A39, 1 chip 8kB memory 6264 and display a 240 × 128 dot-matrix liquid crystal display components. 6A40 match with the T6963C road trip of 68 drives, it will come from the T6963C serial signals into parallel signals to drive the LCD screen on line. This module 128 line dot-matrix, so the two T6A40, the first of which only two of the 60 Road. T6A39 associated with the T6963C drive out 80 road, which will set out from the T6963C serial signals into parallel signals, to drive liquid crystal display on the appropriate column. HY-240128M-201 there are 240 dot-matrix, so the three T6A39.

Single-chip liquid crystal display module and the interface and control

Since the interface for T6963C and Z80 Series 8080 Series MPU, so it can be directly used for 8031's / RD, / WR as a liquid crystal display module of the reading and writing control signals, liquid crystal display module +5 V voltage VDD then, / RESET then reset circuit RC. / CE signal generated by decoding address lines. c / D signal from the address line of a pin A * to provide, A * = 1 for the command port address; A * = 0 for the data port address. Indirect control is through the MPU of the I / O parallel interface, in accordance with the simulation module timing means to achieve indirect control of liquid crystal display module. This access method does not occupy the CPU memory space, and its interface circuit has nothing to do with the timing, the timing completely rely on the realization of software programming.

LCM and the ATmega8535 microcontroller interface connector

ATmega8535 bus as a result of reading and writing cycle 50ns, is 51 times the MCU. For such high-speed MPU is a good indirect way, that is, analog LCD timing controller with LCD controller communications. Indirect method based on the practicality of a strong and simple interface, is given below HY-240128M-201 and AVR-based LCM series ATmega8535 microcontroller-based interface method, the circuit shown in Figure 1.

LCM power supply circuit

HY-240128M-201 power supply needs of the three: the logic of power, backlight power supply and power supply. Which the logic of power through the VSS and VDD pin to provide the two; drive power through the provision of V0 and VEE; backlight power supply through the provision of LEDA and LEDK.

VSS and LEDK can be directly grounded, VDD and LEDA then +5 V; V0 ground through potentiometer, VEE then sliding side to adjust the drive voltage, when the driving voltage is too low, the screen no show black screen too. Attention of the greatest potential value should be between 10KW-20KW.

LCM of the reset circuit

Reset pin for 16-/RST, when high normal low level for the reset state, it will trip out counter and display register cleared. Part of reset circuit of +5 V then 4.7KW resistance, capacitance of 4.7μF to take to achieve, but also directly with the single-chip I / O port connected, through software control, attention, LCM power after the / RST pin maintain the low five clock cycle reduction can be achieved.

LCM command control interface

HY-240128M-201-type LCM external panels provide 5 Command Interface, 15-pin (/ CE) to make to signal end of low effective; 4-pin (C / D) for the channel selection signal, 1 for command channel, 0 for the data channel, at the same time by controlling the / RD and / WR of the input signal can be achieved on the reading and writing instruction and data.

LCM font choice

FS pin 18 is used to select fonts, T6963C requirements: This pin is low, the font for the 8 × 8 dot matrix format, on the contrary to the form of 8 × 6 lattice. Note that this pin can not be suspended, if the font used is 8 × 8, then this pin can be grounded, or the MPU access the I / O pin and software to set the display font.

Control software design

Software used ICCAVR-C language development, it has a strong ability to control the software, that is, by the host CPU through the interface to the LCD module into the module control commands to achieve. The design process mainly consists of two parts, one designed to read and write commands or data LCD, screen, such as initialization and customs common subroutine, in which the main initialization settings include the following: set the text display buffer, graphical display CGRAM area buffer zones and their respective width of the first address and the region, set the mode of LCM and the display mode and select the cursor shape. Another part is the characters and graphics of the display module program, indicating the operation is to want to show the character or graphics information into the display buffer matrix in the specified location. To display the contents of the initialization settings in the display part of the decision, with the generic subprogram, we can construct a variety of display program. When the use of graphical display modes, and characters, Chinese characters and menu similar to the principles of graphical display, the key lies in the establishment of matrix library, the Internet can download a special Chinese character dot-matrix graphic information extraction software (such as zimo21 or Image2Lcd, etc.), they can be extracted 8 × 16 or 16 × 16 or C++ in the compilation of such a state of the matrix language, as well as a variety of image data of the lattice. When ATmega8535-based single-chip liquid crystal display control module, as a result of an indirect access method, so to read / write operation timing quite clear about this.

Timing controller T6963C

When the data-bit instruction set C / D for high-bit-enabled / CE for low-bit write / WR is high, reading status bits / RD for the low, I can read data from the parallel state of the internal controller.

When the data-bit instruction set C / D for high-bit-enabled / CE for low-bit write / WR low, reading status bits / RD is high, I can parallel data write instruction to the internal controller.

When the data-bit instruction set C / D for low-bit-enabled / CE for low-bit write / WR low, reading status bits / RD is high, parallel data through the mouth to write data to the internal controller.

LCD design or data read and write instructions generic subprogram

Stateful Inspection Function LCD

In order to write data or write, we should first check the status of LCM, in order that the status register is ready (STA0) and data-ready (STA1) need to check that only the two at the same time as "1" (LCM idle), the can only write data and command operations, normally, you can design a read-Function to determine the two empty flag / busy status.

Display characters and graphics of Functions

LCD display, including text and graphics display. Graphical display, the LCD screen display of information management unit is the 8 × 1 lattice, known as a graphical display unit. T6963C this unit in the level of the LCD screen is divided into 20 directions, divided into 128 vertical lines, a total of 20 × 128 graphics display units, each graphic display graphic display unit corresponds to a buffer storage unit.,。 When using the text display, write text display buffer state information is not a lattice, but character code, the state information matrix (8 × 8), that is, in the matrix stored in CGRAM. Will be written into the text display character code after the buffer zone, T6963C out from CGRAM character code corresponding to the character of the lattice state information through the ranks of the drive liquid crystal display driver of the characters.

Qing Ping Functions

Display data in the former, it is first necessary to clear the last screen shows the contents of this screen to use the clearance function, simply write to the screen "0" can be realized, the specific process omitted.

LCD Module Debugging Notes

Circuit Design Notes

HY-240128M-201 liquid crystal drive voltage up to-19V, then once the wrong pin in the other, the LCD driver module to control the chip will be destroyed in a short period of time, so power should be repeated before the recognition of the power cord connection correct, it would be preferable to drive the LCD module power and potential to connect through.

Reset line should pay attention to the correctness of state-level. When the product is relatively good, can be directly used in the definition provided by pin reset circuit RC; when bad products in the environment, it would be preferable to / RST from port on MPU.

Debugging Notes

The initial power should gradually adjust potentiometer, so that the output of power supply-side adjustment of about 0V to observe that the situation at the same time monitor the LCD driving voltage, and then slowly adjusted to the normal operating point. In regulating the process, not to bear the LCD module exceed the maximum driving voltage, otherwise it will create damage to the LCD module. If less than or roughly equal to the typical drive voltage was observed to have a color screen changes, which indicates that the domain a little deep in the background color of the edge that the LCD module power supply connections are correct, you can enter the next step. If conditions at room temperature, adjust to a typical value in excess of 2-3V, the not yet observed that the screen has color changes, the regulation would not have to continue.

HY-240128M-201 in a virtual simulation of the robot control system

Control system for virtual simulation using 3D-MAX defusing robot and the establishment of a virtual environment model, OpenGL rendering simulation environment. By controlling the control panel controls the simulation environment in a variety of training in explosives disposal robot moves to complete. The whole system integrated into a control box, control box, including the control panel, display and integrated PC, system of the host-bit machine control panel on the first acquisition of analog data and digital data to the operator panel buttons to operate into control commands, and then every 50ms up through the serial-bit machine to send a command, the data received after the host computer to control the virtual simulation robot, finally, the collection of Virtual PC gesture robot parameters, and then sent through the serial port to the next bit of the host machine part of the host through the SPI data from the machine, from the machine is used to control the liquid crystal display module. Through the liquid crystal display module, the operator can observe the virtual-profile value of the real robot in order to accurately control the robot moves to complete the expected task.

Conclusion

HY-240128M-201-type LCM is a more cost-effective liquid crystal display module, the module with the microcontroller interface is very convenient, but also large amount of information shows that the characters, but also can display graphics and curves, which on one machine interface more friendly. Of course, different models of LCD modules, there are many built-in controller, the set of instructions has some differences, but their design ideas and the process is basically the same.


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