通用液晶显示模块的设计与应用研究
摘要
液晶显示终端在日常生活和现代工业控制的各个方面有着广泛的应用,本文针对工业控制,仪器仪表,和手持设备常用的12864点阵图形液晶显示模块,提出了以51单片机控制液晶显示模块实现显示功能的技术方案,与其他液晶显示模块相比,它具有接口简单,性价比高的优点。
本文根据液晶显示模块12864和51单片机的管脚功能,设计了控制电路的硬件连接图,通过研究芯片的内部时序完成液晶显示的驱动子程序。同时研究了远距离通信时的液晶显示,提出了串口通信和三线制通信两种协议,每种协议里面分别有两种通信方案,分别是单字符通信方案,带控制字的单字符,字符串,可变位数字通信方案。
实验结果表明,在本地显示和通信应用中,液晶显示模块都得到了理想的显示效果,而且作为一种通用模块它是可移植的,它成功的实现了在半导体激光驱动器中的应用,实时显示出电压以及电流值,体现了本次设计的实用价值。
At present,human society has entered the information age, informationindustry has become an important symbol to measure a country'smodernization level. The 80 percent of information that people collect is frompeople’s eyesight, information will eventually realize human machineexchange through information display. Display is an important communicationinterface between human being and machine, the early display is mainlykinescope CRT, but with the progress of science and technology in recentyears, since liquid crystal display (LCD) has many advantages such as lightweight, small size, low power consumption, no radiation hazard, flatrectangular display , stable image and so on, and its price is droppingcontinuously, LCD is gradually replacing CRT's mainstream status. As alow power display, LCD is widely used in some low power systems such ascalculators, digital instruments and industrial control systems. As the mostimportant and the greatest potential display tools in digital information era of21st century, LCD has increasingly broad application prospects. So ,this paperrefers to a new scheme which implements the displaying function through thecontrol of LCD module by 51 MCU, We hope that we can get a general LCDmodule through the design of this paper, as long as the characters in accordwith the displaying standard, we can show them through LCD 12864,moreover, it also can realize the remote displaying by communication mode.
Before the design of hardware circuit, the choice of the components isvery important, in this paper ,we choose a LCD module which adopts STN displaying mode. STN displaying mode overcomes many defects of thetraditional TN LCD ,such as slow electro optic response and unobviousthreshold characteristic. The STN LCD greatly improves the displaycharacteristics, almost all the dot matrix graphics and dot matrix charactersLCD have adopted STN model. so this paper chooses a LCD moduleYM12864, it is a kind of 4 or 8 bit parallel, 2 wire or 3 wire serial interface,the internal contains the international level 1, level 2 simplified Chinesecharacter dot matrix LCD graphics LCD modules, and low voltage and lowpower consumption is its another notable feature. Contrasting with the graphicdot matrix LCD module of the same style, the LCD displaying scheme whichis constructed by YM12864 module is more simple both in the hardwarecircuit or in the display program, and the price of this module is also morelower.
Since the LCD module needs to be controlled by a MCU, this paperchooses STC89C516RD+ MCU, It is a new generation of superanti interference, high speed, low power microcontroller, its instruction codesare fully compatible with the traditional 8051 microcontroller, through theresearch of its internal structure and pins definition, the paper designs the drivecircuit. of YM12864 controlled by a MCU. In the meantime, this paperintroduces the problems we need to pay attention to when we design the PCBboards. Although the hardware circuit in this paper is relatively simple, but inpractical application, the specific circumstance is very complicated, and someusing conditions are even poor. Electromagnetic compatibility is an importantindicator, whether it is good or bad decides whether the entire LCD candisplay normal. This kind of LCD will bring on character twitter or dot on the interface in strong interference conditions, it will seriously affect displayingperformance, so I introduce the whole process of PCB design. However,designing the drive program of LCD module is the most important anddifficult problem, through the study of 12864’s instruction and control signaltiming, This paper designs the drive programs which can display ASCIIcharacters, Japanese characters, Chinese characters and so on. The wholeprogram is wrote by C language, that can make the program moretransplantable.
In order to realize the remote displaying, we need to realizecommunication between microcontrollers. Here, this paper designs twocommunication protocols, one is using 51 MCU onboard serialcommunication module to implement the MCU serial communication, and theother is through the three wire communication protocol, through these twoprotocols we can implement the communication among remote equipmentsand display the contents by LCD module.
Serial communications include asynchronous communications andsynchronous communications, it refers to transferring the messages(binarycoding) between the two sides of communication one bit by one bit.communication. Compared with the parallel communication, although thiskind of communication transfers messages relatively slow, but it can realizelong distance transmission, use less data lines, and save the communicationcosts. However, 51 MCU only has one serial port can be used to carry outserial communication, but in the practical application of STC MCU we alsoneed a serial port to download program. Sometimes we still need to use thesesserial ports to extend one or even more parallel I/O ports except using them to transmit data or download program, And we need to think about here iswhether we can use other ports to replace serial ports, so this paper designsThree wire communication scheme, which can use arbitrary three I / O port of51 MCU to communicate. This realizes the free choice of the ports and alsoincreases the commonality of the LCD module design.
In each protocol, this paper designs two transmission schemes, one issingle character transmission without control characters, although this modecan send out characters and display them by LCD, but it need to call thetransmission function each time it sends out a character, this is bound to affectthe efficiency of transmission, and occupies system resources, so it is rarelyused in the practical application. The other is single character, string,variable bit number communication transmission with control characters. Itcan transmit within 16 characters by only calling the function one time, torealize this, it can change the control characters of transmission function andthen implement the communication of single character, string, variable bitnumber. This mode can improve the efficiency, transmission speed, savesystem resources greatly, and this is also the focus of this paper.
The results of the experiment show that the LCD module has an idealdisplaying function both in the local display and communication applications,and as a general module it is transplantable, it is applied in the semiconductorlaser diode driver successfully, achieves the real time display of voltage andcurrent and reflects this paper’s practical value.
本文根据液晶显示模块12864和51单片机的管脚功能,设计了控制电路的硬件连接图,通过研究芯片的内部时序完成液晶显示的驱动子程序。同时研究了远距离通信时的液晶显示,提出了串口通信和三线制通信两种协议,每种协议里面分别有两种通信方案,分别是单字符通信方案,带控制字的单字符,字符串,可变位数字通信方案。
实验结果表明,在本地显示和通信应用中,液晶显示模块都得到了理想的显示效果,而且作为一种通用模块它是可移植的,它成功的实现了在半导体激光驱动器中的应用,实时显示出电压以及电流值,体现了本次设计的实用价值。
At present,human society has entered the information age, informationindustry has become an important symbol to measure a country'smodernization level. The 80 percent of information that people collect is frompeople’s eyesight, information will eventually realize human machineexchange through information display. Display is an important communicationinterface between human being and machine, the early display is mainlykinescope CRT, but with the progress of science and technology in recentyears, since liquid crystal display (LCD) has many advantages such as lightweight, small size, low power consumption, no radiation hazard, flatrectangular display , stable image and so on, and its price is droppingcontinuously, LCD is gradually replacing CRT's mainstream status. As alow power display, LCD is widely used in some low power systems such ascalculators, digital instruments and industrial control systems. As the mostimportant and the greatest potential display tools in digital information era of21st century, LCD has increasingly broad application prospects. So ,this paperrefers to a new scheme which implements the displaying function through thecontrol of LCD module by 51 MCU, We hope that we can get a general LCDmodule through the design of this paper, as long as the characters in accordwith the displaying standard, we can show them through LCD 12864,moreover, it also can realize the remote displaying by communication mode.
Before the design of hardware circuit, the choice of the components isvery important, in this paper ,we choose a LCD module which adopts STN displaying mode. STN displaying mode overcomes many defects of thetraditional TN LCD ,such as slow electro optic response and unobviousthreshold characteristic. The STN LCD greatly improves the displaycharacteristics, almost all the dot matrix graphics and dot matrix charactersLCD have adopted STN model. so this paper chooses a LCD moduleYM12864, it is a kind of 4 or 8 bit parallel, 2 wire or 3 wire serial interface,the internal contains the international level 1, level 2 simplified Chinesecharacter dot matrix LCD graphics LCD modules, and low voltage and lowpower consumption is its another notable feature. Contrasting with the graphicdot matrix LCD module of the same style, the LCD displaying scheme whichis constructed by YM12864 module is more simple both in the hardwarecircuit or in the display program, and the price of this module is also morelower.
Since the LCD module needs to be controlled by a MCU, this paperchooses STC89C516RD+ MCU, It is a new generation of superanti interference, high speed, low power microcontroller, its instruction codesare fully compatible with the traditional 8051 microcontroller, through theresearch of its internal structure and pins definition, the paper designs the drivecircuit. of YM12864 controlled by a MCU. In the meantime, this paperintroduces the problems we need to pay attention to when we design the PCBboards. Although the hardware circuit in this paper is relatively simple, but inpractical application, the specific circumstance is very complicated, and someusing conditions are even poor. Electromagnetic compatibility is an importantindicator, whether it is good or bad decides whether the entire LCD candisplay normal. This kind of LCD will bring on character twitter or dot on the interface in strong interference conditions, it will seriously affect displayingperformance, so I introduce the whole process of PCB design. However,designing the drive program of LCD module is the most important anddifficult problem, through the study of 12864’s instruction and control signaltiming, This paper designs the drive programs which can display ASCIIcharacters, Japanese characters, Chinese characters and so on. The wholeprogram is wrote by C language, that can make the program moretransplantable.
In order to realize the remote displaying, we need to realizecommunication between microcontrollers. Here, this paper designs twocommunication protocols, one is using 51 MCU onboard serialcommunication module to implement the MCU serial communication, and theother is through the three wire communication protocol, through these twoprotocols we can implement the communication among remote equipmentsand display the contents by LCD module.
Serial communications include asynchronous communications andsynchronous communications, it refers to transferring the messages(binarycoding) between the two sides of communication one bit by one bit.communication. Compared with the parallel communication, although thiskind of communication transfers messages relatively slow, but it can realizelong distance transmission, use less data lines, and save the communicationcosts. However, 51 MCU only has one serial port can be used to carry outserial communication, but in the practical application of STC MCU we alsoneed a serial port to download program. Sometimes we still need to use thesesserial ports to extend one or even more parallel I/O ports except using them to transmit data or download program, And we need to think about here iswhether we can use other ports to replace serial ports, so this paper designsThree wire communication scheme, which can use arbitrary three I / O port of51 MCU to communicate. This realizes the free choice of the ports and alsoincreases the commonality of the LCD module design.
In each protocol, this paper designs two transmission schemes, one issingle character transmission without control characters, although this modecan send out characters and display them by LCD, but it need to call thetransmission function each time it sends out a character, this is bound to affectthe efficiency of transmission, and occupies system resources, so it is rarelyused in the practical application. The other is single character, string,variable bit number communication transmission with control characters. Itcan transmit within 16 characters by only calling the function one time, torealize this, it can change the control characters of transmission function andthen implement the communication of single character, string, variable bitnumber. This mode can improve the efficiency, transmission speed, savesystem resources greatly, and this is also the focus of this paper.
The results of the experiment show that the LCD module has an idealdisplaying function both in the local display and communication applications,and as a general module it is transplantable, it is applied in the semiconductorlaser diode driver successfully, achieves the real time display of voltage andcurrent and reflects this paper’s practical value.
引文
[1] 郭振东,常昌远,吴金,夏炎,魏同立.STN CD 显示驱动技术.电子器件,2001,24(4):338 339.
[2] 张云熙.液晶显示的发展概况.现代显示,1995,3:26 27.
[3] 王军.EDM12864 液晶显示器原理与驱动技术研究.吉林大学硕士学位论文,2004:40 44.
[4] A. Nakazawa, K. Tamai, et al. Ultra low power STN LCDs using multiple lineaddressing formobile telecommunication applications. SID 1999: 277 280.
[5] KitamuraM,NakazawaA,KawaguchiK,MotegiH,HiraiY,KuwataT,KohH.RecentDevelopment inM ulti LineAddressing of STN LCDs. SID 1996D IGEST: 355 356.
[6] Kurum isawa T, Ito A, Yamazaki S, Iino S. High PerformanceU ltra Low Power640*200 Reflective STN Display System U sing Foru L ine SelectionM ethod. SID1996: 351 354.
[7] Hirai Y, KitamuraM. STN LCDs Enhanced byM ultipleL ineAddressing (MLA):Present and FutureApplications. SID 1997: 401 402.
[8] Karel Kuijk E. M inimum2voltage drivingof smallSTN LCDs byoptimizedmultiple row addressing. Journalof the Society for InfotmationDisplay. 2000:301 302.
[9] 马成,何培祥,李庆东.图形点阵式液晶显示模块与 51 单片机的接口设计.应用天地,2007,5(26):76 78.
[10] 李晶皎,刘天华,丁言镁.液晶显示器的 C 语言程序设计.科学出版社,2005,第一版:213 217.
[11] 王幸之,王雷,王闪,钟爱琴.单片机应用系统电磁干扰与抗干扰技术.北京航空航天大学出版社,2006,第一版:595 596.
[12] 姚永平.STC89C51RC/RD+系列单片机器件手册.宏晶科技,2007:14 15.
[13] 舒鑫,郭其一.ST7920 点阵式液晶显示模块的应用研究和编程.液晶与显示,2007,22(2):192 193.
[14] 洪家平.中文图形显示控制芯片 ST7920 的原理与应用.国外电子元器件,2005,1(3):38 40.
[15] 刘瑞新.单片机原理及应用教程.机械工业出版社,2004,第一版:16 19.
[16] 王栓柱.Protel 99 SE 印刷电路板设计技术.西北工业大学出版社,2001,第一版:202 206.
[17] 于枫,宋占伟,李海富.电子工程师制图与制版技术——Protel 99 SE 应用.科学出版社,2004,第一版:20 34.
[18] 谭浩强.C 程序设计.清华大学出版社,1999,第二版:374.
[19] 戴佳,戴卫恒.51 单片机 C 语言应用程序设计实例精讲.电子工业出版社,2006,第一版:350 355.
[20] 周坚.单片机 C 语言轻松入门.北京航空航天大学出版社,2006,第一版:132 139.
[21] 陈小忠,黄宁,赵小侠.单片机接口技术实用子程序.人民邮电出版社,2005,第一版:51 55.
[22] 求是科技.8051 系列单片机 C 程序设计完全手册.人民邮电出版社,2006,第一版:374 379.
[23] 谢维成,杨加国,董秀成.单片机原理与应用及 C51 程序设计.清华大学出版社,2006,第一版:130 133.
[24] 徐爱钧,彭秀华.单片机高级语言 C51 应用程序设计.电子工业出版社,1998,第一版:65 73.
[25] 汪道辉.单片机系统设计与实践.电子工业出版社,2006,第一版:39 43.
[26] 邓军,单江东,张娜,田小建.大功率半导体激光器驱动器的研究与设计.半导体光电,2003,24(5):319 320,370.
[27] 秦恩亮,李亚芬.12 位 A/D 转换器 TLC2543 及与 89C51 的接口.微计算机信息,2001,17(2):64 66.
[28] 王宜怀.12 位 A/D 转换器 TLC2543 与 51 系列单片机接口技术.苏州丝绸工学院学报,1999,19(5):46 47.
[2] 张云熙.液晶显示的发展概况.现代显示,1995,3:26 27.
[3] 王军.EDM12864 液晶显示器原理与驱动技术研究.吉林大学硕士学位论文,2004:40 44.
[4] A. Nakazawa, K. Tamai, et al. Ultra low power STN LCDs using multiple lineaddressing formobile telecommunication applications. SID 1999: 277 280.
[5] KitamuraM,NakazawaA,KawaguchiK,MotegiH,HiraiY,KuwataT,KohH.RecentDevelopment inM ulti LineAddressing of STN LCDs. SID 1996D IGEST: 355 356.
[6] Kurum isawa T, Ito A, Yamazaki S, Iino S. High PerformanceU ltra Low Power640*200 Reflective STN Display System U sing Foru L ine SelectionM ethod. SID1996: 351 354.
[7] Hirai Y, KitamuraM. STN LCDs Enhanced byM ultipleL ineAddressing (MLA):Present and FutureApplications. SID 1997: 401 402.
[8] Karel Kuijk E. M inimum2voltage drivingof smallSTN LCDs byoptimizedmultiple row addressing. Journalof the Society for InfotmationDisplay. 2000:301 302.
[9] 马成,何培祥,李庆东.图形点阵式液晶显示模块与 51 单片机的接口设计.应用天地,2007,5(26):76 78.
[10] 李晶皎,刘天华,丁言镁.液晶显示器的 C 语言程序设计.科学出版社,2005,第一版:213 217.
[11] 王幸之,王雷,王闪,钟爱琴.单片机应用系统电磁干扰与抗干扰技术.北京航空航天大学出版社,2006,第一版:595 596.
[12] 姚永平.STC89C51RC/RD+系列单片机器件手册.宏晶科技,2007:14 15.
[13] 舒鑫,郭其一.ST7920 点阵式液晶显示模块的应用研究和编程.液晶与显示,2007,22(2):192 193.
[14] 洪家平.中文图形显示控制芯片 ST7920 的原理与应用.国外电子元器件,2005,1(3):38 40.
[15] 刘瑞新.单片机原理及应用教程.机械工业出版社,2004,第一版:16 19.
[16] 王栓柱.Protel 99 SE 印刷电路板设计技术.西北工业大学出版社,2001,第一版:202 206.
[17] 于枫,宋占伟,李海富.电子工程师制图与制版技术——Protel 99 SE 应用.科学出版社,2004,第一版:20 34.
[18] 谭浩强.C 程序设计.清华大学出版社,1999,第二版:374.
[19] 戴佳,戴卫恒.51 单片机 C 语言应用程序设计实例精讲.电子工业出版社,2006,第一版:350 355.
[20] 周坚.单片机 C 语言轻松入门.北京航空航天大学出版社,2006,第一版:132 139.
[21] 陈小忠,黄宁,赵小侠.单片机接口技术实用子程序.人民邮电出版社,2005,第一版:51 55.
[22] 求是科技.8051 系列单片机 C 程序设计完全手册.人民邮电出版社,2006,第一版:374 379.
[23] 谢维成,杨加国,董秀成.单片机原理与应用及 C51 程序设计.清华大学出版社,2006,第一版:130 133.
[24] 徐爱钧,彭秀华.单片机高级语言 C51 应用程序设计.电子工业出版社,1998,第一版:65 73.
[25] 汪道辉.单片机系统设计与实践.电子工业出版社,2006,第一版:39 43.
[26] 邓军,单江东,张娜,田小建.大功率半导体激光器驱动器的研究与设计.半导体光电,2003,24(5):319 320,370.
[27] 秦恩亮,李亚芬.12 位 A/D 转换器 TLC2543 及与 89C51 的接口.微计算机信息,2001,17(2):64 66.
[28] 王宜怀.12 位 A/D 转换器 TLC2543 与 51 系列单片机接口技术.苏州丝绸工学院学报,1999,19(5):46 47.