ascii lcd display made in china

You need a display with a lot more resolution, like an OLED graphics display. You are also struggling against a microcontroller that doesn"t have support for Unicode. It"s just not up to the job. You"d be much better off with a Raspberry Pi and a screen like a smart-phone color LCD screen. Install Linux and you can have native support for Unicode.

In this tutorial i am going to print/display ASCII characters on 16×2 lcd using pic16f877 microcontroller. Lcd is interfaced with pic microcontroller in 8-bit mode. Code is written in c language. High tech c compiler is used to compile code and code is written in Mp-lab ide. Interfacing 16×2 lcd with pic microcontroller and displaying characters on lcd is very easy. Only the portion which is little bit complex is how to generate/display ASCII characters on lcd. Well you don’t need to generate ASCII characters they are already present in the 16×2 lcd controller (HD44780) Ram, like other characters and numbers. You just need to know how to invoke the ASCII characters to be displayed on the lcd screen.

If you are new in the field of microcontrollers and lcd’s and don’t know about lcd pin out, working and internal structure of lcd then please go through the following tutorials. They will clear you about the working of 16×2 lcd. You will learn how to display characters on lcd? Difference between commands and data send to lcd? It will also explain you about how to use lcd in 4-bit and 8-bit mode.

The circuit diagram of the project is given below. Port-B of Pic16f877 microcontroller is connected with data pins of 16×2 lcd. It means Port-B is used to send commands and data to 16×2 lcd. Lcd control signals(read/write, enable, register select) are provided using individual bits of Port-D. All the other connections are normal connections applying +5 volts to microcontroller and lcd. You can see the circuit diagram given below. Rs(Register select) is connected to Port-D Pin#6. En(Enable) is connected to Port-D Pin#7. Read/Write pin is grounded. Lcd will always remain in write state since we made the R/W pin ground.

Coming to the code portion, I first include the header file htc.h. If you are using high tech c compiler always include this library, this library is necessary to be included in every project that is going to be compiled with high tech c compiler. It contains the compilers directives etc. Then the frequency of the oscillator is defined which is 20 MHz. Then individual pins of Port-D are defined. These pins are used to provide control signals to lcd. delay() function is used to generate some arbitrary delay where necessary. lcdcmd() function is sending commands to lcd with control signals. display() function is sending data to lcd with control signals. lcdint() function is initializing our lcd(8-bit mode, display on ,cursor off etc).

In the main function two instructions are invoking ascii characters. The instructioni=j/10; wherej is integer(int) and i is character(char). Now when we divide two integers and save result in character(char) variable. The result is stored in ascii format. Sincej is 0 and dividing 0 by 10 gives 0. So icontains 0, ASCII value of zero.

The ascii character 0 is present at address 0x30. To go to address 0x00 negate 0x30 from 0x30. The instruction i=i-0x30; is doing the same job. First i contains 0x30 after executing i=i-0x30 i contains 0x00. Hence we are at starting address of ascii characters. Now increment the address one by one and display the ascii character associated with that address on the lcd screen.

Notethat the ascii characters of the HD44780 controller differs from the standard ascii characters. The HD44780 controller contains ascii characters in the format given on the right side. Some addresses are also void. So don’t get confused when you see the characters like below displayed on your lcd screen.

Total digits in ram of 16×2 lcd are 256. So i decided to display them all. It contains ASCII, numeric, alphabet and special characters(Chinese). Some address are void so nothing will display on the lcd screen across these addresses.

Here is a simple project/tutorial in which i will teach you about how to display ASCII characters on character lcd’s. In this tutorial i am using 16×2 lcd. You can use any other size of lcd if you want but be sure to change the lcd initialization statements in the code. Character lcd’s have a built in controller which controls its operations. Usually character lcd’s has HD44780 controller in them. This controller has pre-defined ASCII characters stored in its ROM(read only memory). When we send any character from external microcontroller on lcd data pins and write it to lcd screen, what happens actually is, the character is received by the lcd controller. 16×2 lcd controller then matches the character with its internal ROM characters if matches is found it then displays the character on 16×2 lcd screen.

16×2 lcd is not limited to displaying ASCII characters. Its internal ROM also contains some special Chinese language characters some special shapes. We can display all of them by calling their addresses in ROM.

We can also display custom character’s on 16×2 lcd. Bycustom characters i mean we can create our own characters and can display them on 16×2 lcd. To display custom characters we utilize the internal CG-RAM(Character generated Random Access Memory) of 16×2 lcd controller. Custom characters generation are not part of this project. I have separate tutorials on them.

Character lcd’s can display character of size 5×8 and 5×10. In 5×8 dimension 5 represents numbers of rows and 8 represents number of coulombs. Sp in a cube of 5×8 and 5×10 we can display our characters. Normally we display characters in 5×7 font. The 8th coulomb we left is for the cursor movement. 5×10 font is not popular and limited characters can be displayed in 5×10 font. Total 32 characters can be displayed in 5×10 matrix and 208 can be displayed in 5×8 matrix cube. An image of characters with their addresses in ROM of hd44780 lcd controller data sheet is below.

Going through the data sheet of HD44780 lcd controller. You will see the character’s that are stored in the ROM(random access memory) of the controller. Character’s with their addresses are listed in the data sheet. You can see the characters and their addresses in the picture given above.

I am going to invoke the addresses of each characters/numbers special characters ASCII characters stored in the ROM and they will display on 16×2 lcd screen automatically. On first line of lcd i am printing the decimal value of the ASCII character and on the second line i will display the original ASCII character. whole of the ASCII characters in lcd controller ROM will be displayed on lccd screen one by one. The code is placed in while(1) loop so the process will remain continuous unless the power is cut off.

Lcd is interfaced in 8-bit mode with 8051 microcontroller. Lcd data pins are connected to port-2 of 89c51 microcontroller. Lcd rs(register select) pin is connected to port-3 pin#5. Lcd rw(read write) pin is connected to port-3 pin#7 and lcd en(enable) pin is connected to port-3 pin#6. Circuit diagram of the project is below.

The code is very simple we hope that you are already familiar with c/c++ programming language. Code is written and compiled in keil uvision ide. First of all the header file re51.h is included. we have to include in our every project which includes 8051 microcontroller in it. Then the lcd rs(register set) rw(read/write) and en(Enable) pins are defined.

Just copy the code and made your circuit burn the code in your microcontroller. Power the circuit and ascii characters will appear on your 16×2 lcd screen. You can also use another size of screen but take care you have to change just only one statement lcdcmd(0x38). If you want to know about the lcd initialization just visit thebelow tutorial.

The 1.8inch LCD uses the PH2.0 8PIN interface, which can be connected to the Raspberry Pi according to the above table: (Please connect according to the pin definition table. The color of the wiring in the picture is for reference only, and the actual color shall prevail.)

ST7735S is a 132*162 pixel LCD, and this product is a 128*160 pixel LCD, so some processing has been done on the display: the display starts from the second pixel in the horizontal direction, and the first pixel in the vertical direction. Start to display, so as to ensure that the position corresponding to the RAM in the LCD is consistent with the actual position when displayed.

The LCD supports 12-bit, 16-bit and 18-bit input color formats per pixel, namely RGB444, RGB565, RGB666 three color formats, this routine uses RGB565 color format, which is also a commonly used RGB format

Note: Different from the traditional SPI protocol, the data line from the slave to the master is hidden since the device only has display requirement.

Framebuffer uses a video output device to drive a video display device from a memory buffer containing complete frame data. Simply put, a memory area is used to store the display content, and the display content can be changed by changing the data in the memory.

If you need to draw pictures, or display Chinese and English characters, we provide some basic functions here about some graphics processing in the directory RaspberryPi\c\lib\GUI\GUI_Paint.c(.h).

Set points of the display position and color in the buffer: here is the core GUI function, processing points display position and color in the buffer.

The fill color of a certain window in the image buffer: the image buffer part of the window filled with a certain color, usually used to fresh the screen into blank, often used for time display, fresh the last second of the screen.

Write Ascii character: In the image buffer, use (Xstart Ystart) as the left vertex, write an Ascii character, you can select Ascii visual character library, font foreground color, font background color.

Write English string: In the image buffer, use (Xstart Ystart) as the left vertex, write a string of English characters, you can choose Ascii visual character library, font foreground color, font background color.

Write numbers: In the image buffer,use (Xstart Ystart) as the left vertex, write a string of numbers, you can choose Ascii visual character library, font foreground color, font background color.

Display time: in the image buffer,use (Xstart Ystart) as the left vertex, display time,you can choose Ascii visual character font, font foreground color, font background color.;

2. The module_init() function is automatically called in the INIT () initializer on the LCD, but the module_exit() function needs to be called by itself

Python has an image library PIL official library link, it do not need to write code from the logical layer like C, can directly call to the image library for image processing. The following will take 1.54inch LCD as an example, we provide a brief description for the demo.

Note: Each character library contains different characters; If some characters cannot be displayed, it is recommended that you can refer to the encoding set ro used.

The demo is developed based on the HAL library. Download the demo, find the STM32 program file directory, and open the LCD_demo.uvprojx in the STM32\STM32F103RBT6\MDK-ARM directory to check the program.

For the screen, if you need to draw pictures, display Chinese and English characters, display pictures, etc., you can use the upper application to do, and we provide some basic functions here about some graphics processing in the directory STM32\STM32F103RB\User\GUI_DEV\GUI_Paint.c(.h)

Image buffer part of the window filling color: the image buffer part of the window filled with a certain color, generally as a window whitewashing function, often used for time display, whitewashing on a second

Write Ascii character: In the image buffer, at (Xstart Ystart) as the left vertex, write an Ascii character, you can select Ascii visual character library, font foreground color, font background color.

Write English string: In the image buffer, use (Xstart Ystart) as the left vertex, write a string of English characters, can choose Ascii visual character library, font foreground color, font background color.

Write numbers: In the image buffer,use (Xstart Ystart) as the left vertex, write a string of numbers, you can choose Ascii visual character library, font foreground color, font background color.

Display time: in the image buffer,use (Xstart Ystart) as the left vertex, display time,you can choose Ascii visual character font, font foreground color, font background color.

image.cpp(.h): is the image data, which can convert any BMP image into a 16-bit true color image array through Img2Lcd (downloadable in the development data).

For the screen, if you need to draw pictures, display Chinese and English characters, display pictures, etc., you can use the upper application to do, and we provide some basic functions here about some graphics processing in the directory GUI_Paint.c(.h)

Write Ascii character: In the image buffer, at (Xstart Ystart) as the left vertex, write an Ascii character, you can select Ascii visual character library, font foreground color, font background color.

Write English string: In the image buffer, use (Xstart Ystart) as the left vertex, write a string of English characters, can choose Ascii visual character library, font foreground color, font background color.

Write numbers: In the image buffer,use (Xstart Ystart) as the left vertex, write a string of numbers, you can choose Ascii visual character library, font foreground color, font background color.

Write numbers with decimals: at (Xstart Ystart) as the left vertex, write a string of numbers with decimals, you can choose Ascii code visual character font, font foreground color, font background color

Display time: in the image buffer,use (Xstart Ystart) as the left vertex, display time,you can choose Ascii visual character font, font foreground color, font background color.

In the previous chapter, we have discussed how a character LCD is interfaced with a PIC microcontroller in 8-bit mode, where we used predefined characters stored in the LCD to display our data. In this article, we will learn more about the LCD and how we can create and use custom characters.

DDRAM or “Data Display Random Access Memory” is the working data buffer of the display. Each character on the display has a corresponding DDRAM location and the byte loaded in DDRAM controls which character is displayed.

CGROM or “Character Generation Read Only Memory” holds all the standard patterns for the 5 x 7 dot matrix characters. For instance, if you want to display character “A”, you would send ASCII code 65 (decimal) to the DDRAM. The display controller looks up the pattern of dots to display for this code in the CGROM and lights up the ones appropriate for “A”. The CGROM contents depend on the particular character set and model of display, US, Chinese etc. and cannot be changed.

CGRAM or “Character Generation Random Access Memory” allows the user to define special supplementary non-standard character types that are not in the CGROM. You can load your own dot pattern shapes and call these up for display.

For making custom patterns we need to write values to the CGRAM area defining which pixel to glow. These values are to be written in the CGRAM address starting from 0x40. CGRAM has a total of 64 Bytes. For LCD using 8×5 dots for each character, you can define a total of 8 user defined patterns (1 Byte for each row and 8 rows for each pattern).

Custom characters are assigned fixed display codes from 0 to 7 for pattern stored in the location pointed by CGRAM address 0x40, 0x48, 0x56… and so on. So, if the user wants to display second pattern (pattern stored at CGRAM address 0x48), simply call the data function with value 1 as an argument at a desired location in the LCD.

To display the sequence in the LCD, we need to specify the position on LCD and which pattern to display at the position. Provide adequate delay in between frames to observe the sequence distinctly.

The 1.14inch LCD uses the PH2.0 8PIN interface, which can be connected to the Raspberry Pi according to the above table: (Please connect according to the pin definition table. The color of the wiring in the picture is for reference only, and the actual color shall prevail.)

The built-in controller used in this LCD is ST7789VW, which is an LCD controller with 240 x RGB x 320 pixels, while the pixels of this LCD itself is 135(H)RGB x 240(V). There are two types of horizontal and vertical screens, so the internal RAM of the LCD is not fully used.

The LCD supports 12-bit, 16-bit, and 18-bit input color formats per pixel, namely RGB444, RGB565, and RGB666 three color formats, this demo uses RGB565 color format, which is also a commonly used RGB format

Note: Different from the traditional SPI protocol, the data line from the slave to the master is hidden since the device only has display requirement.

Framebuffer uses a video output device to drive a video display device from a memory buffer containing complete frame data. Simply put, a memory area is used to store the display content, and the display content can be changed by changing the data in the memory.

If you need to draw pictures, or display Chinese and English characters, we provide some basic functions here about some graphics processing in the directory RaspberryPi\c\lib\GUI\GUI_Paint.c(.h).

Set points of the display position and color in the buffer: here is the core GUI function, processing points display position and color in the buffer.

The fill color of a certain window in the image buffer: the image buffer part of the window filled with a certain color, usually used to fresh the screen into blank, often used for time display, fresh the last second of the screen.

Write Ascii character: In the image buffer, use (Xstart Ystart) as the left vertex, write an Ascii character, you can select Ascii visual character library, font foreground color, font background color.

Write English string: In the image buffer, use (Xstart Ystart) as the left vertex, write a string of English characters, you can choose Ascii visual character library, font foreground color, font background color.

Write numbers: In the image buffer,use (Xstart Ystart) as the left vertex, write a string of numbers, you can choose Ascii visual character library, font foreground color, font background color.

Display time: in the image buffer,use (Xstart Ystart) as the left vertex, display time,you can choose Ascii visual character font, font foreground color, font background color.;

2. The module_init() function is automatically called in the INIT () initializer on the LCD, but the module_exit() function needs to be called by itself

Python has an image library PIL official library link, it do not need to write code from the logical layer like C, can directly call to the image library for image processing. The following will take 1.54inch LCD as an example, we provide a brief description for the demo.

Note: Each character library contains different characters; If some characters cannot be displayed, it is recommended that you can refer to the encoding set ro used.

ERM19264_UC1609_TEXT, Library for ERM19264-5 v3 LCD (UC1609C controller) for the Arduino eco-system. This is a light weight, text only version of the main ERM19264_UC1609 library.

None of these instructions will produce a change on the screen without a display.display(); method. If your script does not appear to be working check you have included this line at the bottom of your screen changing code.

Marlin deals with a variety of different displays and needs to display a lot of different languages in different scripts on them, within their capabilities. The system described here solves some of the related problems that need to be overcome with in a limited environment.

On all these displays you can define 8 custom symbols to display at once. In Marlin these characters are used on the Boot Screen, and on the Info Screen for the Bed Temp, Degree symbol, Thermometer, “FR” (feed-rate), Clock, and Progress Bar. On the SD Card listing screens some of these characters are re-used again for Up-level, Folder, and Refresh.

Graphical displays provide complete freedom to display whatever we want, so long as we provide a program for it. Currently we deal with 128x64 Pixel Displays and divide this area into ~5 Lines with ~22 columns. So we need monospace fonts with a bounding box of about 6x10. Until now we’ve been using a custom Marlin font similar to ISO10646-1 but with special symbols at the end, which made ‘ü’ and ‘ä’ inaccessible at 6x10 size.

All these languages (except English) normally use extended symbols not contained in US-ASCII. Even the English translation uses some Symbols not in US-ASCII (e.g., ‘\002’ for Thermometer, STR_h3 for ‘³’). In the code itself symbols may be used without taking into account the display they’re written on.

The upshot of all this is that on Western displays you’ll see a ‘~’ while on Cyrillic an “arrow coming from top - pointing to left” (which is quite the opposite of what the programmer wanted). The Germans want to use “ÄäÖöÜüß”, the Finnish at least “äö”. Other European languages want to see their accents too. For other scripts like Cyrillic, Japanese, Greek, Hebrew, … you have to find totally different symbol sets.

The Japanese translator dealt with two scripts, introducing a special font for Graphical Displays and making use of the Japanese extended character displays. Thus he ended up with two pretty unreadable language.h files full of ‘\xxx’ definitions. Other languages either tried to avoid words that included special symbols or just used the basic symbols without the accents, dots… whatever.

Make output functions that count the number of chars written and switch the font to Marlin symbols and back when needed. (ultralcd_impl_DOGM.h) (ultralcd_impl_HD44780.h)

Make three fonts to simulate the HD44780 charsets on dogm-displays. With these fonts the translator can check how the translation will look on character-based displays.

Direct HD44780 Translation Symbols outside the normal ASCII-range (32-128) are written as “\xxx” and point directly into the font of the hardware declared in Configuration.h.

If you make extensive use, your file will look like language_kana.h and your language file will only work on one of the displays (in this case DISPLAY_CHARSET_HD44780 == JAPANESE).

If you want to make use of more than a few symbols outside standard ASCII or want to improve the portability to more types of displays, use UTF-8 input. Which means defining another mapper.

The mapper_tables do their best to find a similar symbol in the HD44780fonts (for example, replacing small letters with the matching capital letters). But they may fail to find a match and will output a ‘?’. There are combinations of language and display which simply have no corresponding symbols - like Cyrillic on a Japanese display or _vice-versa. In those cases the compiler will throw an error.

In short: Choose a mapper that works with the symbols you want to use. Use only symbols matching the mapper. On Full Graphic Displays all symbols should be fine. Using the graphical display, you can test for bad substitutions or question-marks that would appear on character displays by defining SIMULATE_ROMFONT and trying the different variants.

If you get a lot of question marks on the Hitachi-based displays with your new translation, maybe creating an additional language file with the format language_xx_utf8.h is the way to go.

In this file specify the mapper (e.g., MAPPER_NON) and font (e.g., DISPLAY_CHARSET_ISO10646_1) and translate some of the strings defined in language_en.h. (Remove #ifndef #endif from the defines.)

If there’s no existing mapper for your language then things get a bit more complex. With the Hitachi-based displays you can’t make something useful without a matching charset. For graphical display… let’s take the example of Greek: Find a matching charset. (Greek and Coptic)

Provide a bitmap font containing the symbols in the right size (5x9 to 6x10 recommended). Normal ASCII characters should occupy 1 to 127, and the upper 128 places should be populated with your special characters.

If you want to integrate an entirely new variant of a Hitachi-based display. Add it to Configuration.h and define mapper tables in utf_mapper.h. You may need to add a new mapper function.

The length of strings (for menu titles, edit labels, etc.) is limited. “17 characters” was a crude rule of thumb. Obviously 17 is too long for a 16x2 display. So, language files are free to check the LCD width and provide shorter strings in the following manner:

On 16x2 displays, strings suited to a 20x4 display will be chopped to fit. So if shorter string isn’t provided, at least make similar strings different early in the string. (‘Someverylongoptionname x’ -> ‘x Somverylongoptionname’)

To find out which character set your hardware uses, set #define LCD_LANGUAGE test and compile Marlin. In the menu you’ll see two lines from the upper half of the character set: JAPANESE displays “バパヒビピフブプヘベペホボポマミ”

If you get an error message about “missing mappers” during compilation - lie about your display’s hardware font to see at least some garbage, or select another language.

LCD_LANGUAGE: The LCD language and encoding to compile in. For example, pt-br_utf8 specifies Portuguese (Brazil) in UTF-8 format with a mapper. For a faster, lighter, but non-accented translation you might choose pt-br instead.

MAPPER_C2C3: This is a mapper set by some language files, and indicates that Marlin should use the mapper for Unicode pages C2 and C3. In this mapper, strings are converted from raw UTF-8 input to single ASCII characters from 0-127, and indexes from 0-127 within the combined two 64-glyph pages C2 and C3.

SIMULATE_ROMFONT: Languages can opt to use the HD44780 ROM font special characters on graphical display. This method can be used for accented Western, Katakana, and Cyrillic if they don’t supply their own fonts, or just for testing character-based mappers on a graphical display.

DISPLAY_CHARSET_ISO10646_1: To support a graphical display, a language file must specify either SIMULATE_ROMFONT or a display character set. This specific option selects the Western font for use on graphical display. Others include ISO10646_5, ISO10646_KANA, ISO10646_GREEK, ISO10646_CN, ISO10646_TR, and ISO10646_PL. If no character set is specified, Marlin assumes ISO10646_1.

MAPPER_ONE_TO_ONE: Most character sets on graphical displays (including SIMULATE_ROMFONT) map the character index directly to its position in the upper half of the font. This is possible for character sets that have only 2 contiguous pages of Unicode containing all the special characters. Other mappers use logic or a lookup table to locate the glyph.

The present invention proposes a kind of on alphanumeric display terminal, realize the thought of Chinese character demonstration and the plug-in type Chinese character display circuit board that designs according to this thought through once calling Chinese character generator, do not needing to change circuit on existing 3102 alphanumeric display terminals and on the IBM-PC microcomputer, just can realize that Chinese character shows as long as insert this circuit board.

Chinese character display circuit of the present invention has two kinds (Fig. 2), (Fig. 3).Their design philosophy is: add Chinese character generator in display circuit, adopt general terminal to show that the mode of ASCII character character shows Chinese character, promptly pure character Display mode.Because the model difference of CRTC chip has adopted different technology when realizing this thought.Here introduce two kinds of implementations.

(1) for the CRTC chip that is no less than 14 address wires, (14 OPADD lines being arranged as 6845 chips) is because it can reach 16K to the directly address scope of character generator ROM.That is to say can be directly to more than 16,000 character pattern directly addresss with 6845.So concerning national standard one second Chinese character base, the 6845th, can directly satisfy the addressing requirement.Not as 8275,, and to adopt the address synthetic technology because have only 7 address wires.But, because terminal or micro computer that we use now.The data line majority all is 8, and kanji code is two byte ASCII character, and just there is a problem in this, in order to satisfy 6845 pairs of Kanji character generator addressing, requires to have the address code of two bytes, and because data line has only 8, once can only send a syllabified code.In order to satisfy complete compatible needs, do not allow again to wait a bat, form two byte code addresses.Therefore, adopted the method for binary channels display refresh buffer to solve here, promptly open up two identical refresh buffer zone (promptly 16 * 2K=4KB).These two addresses of refreshing buffer zone are interlaced, and one is the odd address entirely, and one is even address entirely, and these two buffer zones are under the synchronous clock effect, by CPU and CRTC alternate access.A kanji code is sent to the same position of two buffer zones respectively.14 address wires of CRTC are simultaneously to two buffer zones (8).(9) control addressing.So once just can produce 14 Kanji character generator address code, thereby realize addressing Kanji character generator.

Under the control of synchronous clock, CRTC and CPU are in turn to buffer zone 1,2 (8), (9) control.When showing ascii character, code is only delivered on the buffer zone 2 (9), and another buffer zone (8) can be used for the attribute or the difference of code.To ascii character generator (11) addressing, finish the demonstration of ascii character by buffer zone 2 (9).When showing Chinese character, code is delivered to respectively on the buffer zone that the address is M and M+1, in fact be exactly at two buffer zones 1,2 (8), in (9), by 14 address wires of CRTC simultaneously to two buffer zones 1,2 (8), (9) directly address, the address code of generation Kanji character generator (10) realizes the output (Fig. 3) of Kanji character generator dot matrix.

In a word, because 6845 chips have determined it when realizing that Chinese character shows, needn"t adopt the address synthetic technology, and adopt the method for double buffering to satisfy the addressing requirement.If little process chip number of data lines in the future according to also changing 16 into, shows that with 6845CRTC Chinese character just will become the same with ascii character simple so.

(2) to the CRTC chip of 7 OPADD lines is only arranged, (as the 8275CRTC chip) can not satisfy the addressing requirement of several thousand Chinese characters because its output addressed line has only 7.Therefore to adopt the address synthetic technology; With the synthetic 14 bit address sign indicating numbers of two bytes,, make 7 character address lines of chip output produce 14 address wires, so that make the directly address scope of character generator ROM reach 16K promptly with the synthetic Chinese character address of the address wire of two ASCII character.To satisfy the directly address requirement of Chinese character generator.

The course of work that the 8275CRTC Chinese character is shown can be described below specifically: the solid box in circuit block diagram (Fig. 1) is represented common western language character display circuit block diagram, and 8275CRTC is only had 7 character address lines, and (CCO～CCb) produces 128 character addresses.The character address line is connected to the western language character generator, be used for control character generator output character dot matrix; The dot matrix byte is fed to the teletron circuit after changing over serial data by a parallel serial shift circuit.The Chinese character display circuit has increased frame of broken lines part (Fig. 1) on the basis of character display circuit.By Chinese character generator address combiner circuit (2); Door strobe generation circuit (3); Chinese character generator (4) three parts are formed.

In Chinese character display circuit (Fig. 2), (Fig. 3), all comprising Chinese character generator (Chinese character base).The present invention adopts new E PROM(as 27128 chips) as the Chinese character base storaging chip, its total volume 256K allows to show 8192 Chinese characters.Chinese character dot matrix is arranged as 14 * 15.Because adopt novel chip design Chinese character base, whole Chinese character display part uses the Ic sheet always to teach minimizing; Thereby reduced the electrical source consumption of Chinese character display part, in the Chinese terminal of new design or repacking, can directly use intrinsic power circuit; And make very little that whole Chinese character display circuit can do.

In order to realize that the Comprehensive Control and the encode Chinese characters for computer conversion of above-mentioned two kinds of Chinese character display circuits are also needed a monitoring module, include the 3K watchdog routine and also be solidificated among the EPROM.It removes effect: 1. to the setting and the identification of western language ASCII character and Chinese character storage code sign; Western language shows that the ASCII character of same byte represents, Chinese character storage code is with two byte representations, wherein Chinese character store code the first byte extreme higher position 1 as a token of.In view of the above western language and Chinese character are discerned.Here the second byte most significant digit of like that Chinese character not being stored code as hanzi system also puts 1, but this position is become 0, and purpose is to make the Chinese character generator capacity can extend to the 16K word.2. use improved " dichotomy " that input coding for Chinese character is changed fast, make it to become unified inside storage sign indicating number.3. designed the particular algorithm that addressing unified in western language and Chinese character adapting to the requirement of " synthetic address ", and satisfied screen and refreshed the needs that Chinese character base is called fast.

Owing to adopted above-mentioned each technical measures, advantage of the present invention is: 1. make the CRTC of 7 addressed line chip only arranged (as 8275 or μ PD3301) enlarged the directly address scope greatly, thereby the Chinese character display speed is greatly improved.Usually the Chinese character display speed of hanzi system can only reach 2400～4800 bauds, and the present invention can reach 9600 bauds, and is promptly identical with the western language display speed.2. to show in a screen what different Chinese characters are without any restriction.And on the terminal of general hanzi system, in a frame, surpass 256(or 384 as if different Chinese characters) to do special processing usually.3. having eliminated the screen that causes because of " secondary calls " disturbs.Save type storehouse and small library simultaneously, saved many storage bodies and memory cell.

(1) expression 8275CRTC chip in the accompanying drawing; (2) be Chinese character generator address combiner circuit; (3) be a strobe generation circuit; (4) be Chinese character generator; (5) be the western language character generator; (6) be shift circuit; (7) be the teletron circuit; (8) be that the address is the refresh buffer 1 of M; (9) be that the address is the buffer zone that refreshes of M+1; (10) be Kanji character generator; (11) be the ASCII character character generator.

Nextion is a Human Machine Interface （HMI） solution combining an onboard processor and memory touch display with Nextion Editor software for HMI GUI project development.

Using the Nextion Editor software, you can quickly develop the HMI GUI by drag-and-drop components (graphics, text, button, slider, etc.) and ASCII text-based instructions for coding how components interact on the display side.

Nextion HMI display connects to peripheral MCU via TTL Serial (5V, TX, RX, GND) to provide event notifications that peripheral MCU can act on, the peripheral MCU can easily update progress, and status back to Nextion display utilizing simple ASCII text-based instructions.

In this Arduino tutorial we will learn how to connect and use an LCD (Liquid Crystal Display)with Arduino. LCD displays like these are very popular and broadly used in many electronics projects because they are great for displaying simple information, like sensors data, while being very affordable.

You can watch the following video or read the written tutorial below. It includes everything you need to know about using an LCD character display with Arduino, such as, LCD pinout, wiring diagram and several example codes.

An LCD character display is a unique type of display that can only output individual ASCII characters with fixed size. Using these individual characters then we can form a text.

If we take a closer look at the display we can notice that there are small rectangular areas composed of 5×8 pixels grid. Each pixel can light up individually, and so we can generate characters within each grid.

The number of the rectangular areas define the size of the LCD. The most popular LCD is the 16×2 LCD, which has two rows with 16 rectangular areas or characters. Of course, there are other sizes like 16×1, 16×4, 20×4 and so on, but they all work on the same principle. Also, these LCDs can have different background and text color.

It has 16 pins and the first one from left to right is the Groundpin. The second pin is the VCCwhich we connect the 5 volts pin on the Arduino Board. Next is the Vo pin on which we can attach a potentiometer for controlling the contrast of the display.

Next, The RSpin or register select pin is used for selecting whether we will send commands or data to the LCD. For example if the RS pin is set on low state or zero volts, then we are sending commands to the LCD like: set the cursor to a specific location, clear the display, turn off the display and so on. And when RS pin is set on High state or 5 volts we are sending data or characters to the LCD.

Next comes the R/W pin which selects the mode whether we will read or write to the LCD. Here the write mode is obvious and it is used for writing or sending commands and data to the LCD. The read mode is used by the LCD itself when executing the program which we don’t have a need to discuss about it in this tutorial.

Next is the E pin which enables the writing to the registers, or the next 8 data pins from D0 to D7. So through this pins we are sending the 8 bits data when we are writing to the registers or for example if we want to see the latter uppercase A on the display we will send 0100 0001 to the registers according to the ASCII table. The last two pins A and K, or anode and cathode are for the LED back light.

After all we don’t have to worry much about how the LCD works, as the Liquid Crystal Library takes care for almost everything. From the Arduino’s official website you can find and see the functions of the library which enable easy use of the LCD. We can use the Library in 4 or 8 bit mode. In this tutorial we will use it in 4 bit mode, or we will just use 4 of the 8 data pins.

We will use just 6 digital input pins from the Arduino Board. The LCD’s registers from D4 to D7 will be connected to Arduino’s digital pins from 4 to 7. The Enable pin will be connected to pin number 2 and the RS pin will be connected to pin number 1. The R/W pin will be connected to Ground and theVo pin will be connected to the potentiometer middle pin.

We can adjust the contrast of the LCD by adjusting the voltage input at the Vo pin. We are using a potentiometer because in that way we can easily fine tune the contrast, by adjusting input voltage from 0 to 5V.

Yes, in case we don’t have a potentiometer, we can still adjust the LCD contrast by using a voltage divider made out of two resistors. Using the voltage divider we need to set the voltage value between 0 and 5V in order to get a good contrast on the display. I found that voltage of around 1V worked worked great for my LCD. I used 1K and 220 ohm resistor to get a good contrast.

There’s also another way of adjusting the LCD contrast, and that’s by supplying a PWM signal from the Arduino to the Vo pin of the LCD. We can connect the Vo pin to any Arduino PWM capable pin, and in the setup section, we can use the following line of code:

It will generate PWM signal at pin D11, with value of 100 out of 255, which translated into voltage from 0 to 5V, it will be around 2V input at the Vo LCD pin.

First thing we need to do is it insert the Liquid Crystal Library. We can do that like this: Sketch > Include Library > Liquid Crystal. Then we have to create an LC object. The parameters of this object should be the numbers of the Digital Input pins of the Arduino Board respectively to the LCD’s pins as follow: (RS, Enable, D4, D5, D6, D7). In the setup we have to initialize the interface to the LCD and specify the dimensions of the display using the begin()function.

The cursor() function is used for displaying underscore cursor and the noCursor() function for turning off. Using the clear() function we can clear the LCD screen.

In case we have a text with length greater than 16 characters, we can scroll the text using the scrollDisplayLeft() orscrollDisplayRight() function from the LiquidCrystal library.

We can choose whether the text will scroll left or right, using the scrollDisplayLeft() orscrollDisplayRight() functions. With the delay() function we can set the scrolling speed.

So, we have covered pretty much everything we need to know about using an LCD with Arduino. These LCD Character displays are really handy for displaying information for many electronics project. In the examples above I used 16×2 LCD, but the same working principle applies for any other size of these character displays.