JPH02214929A - Character display system for liquid crystal matrix - Google Patents

Abstract

PURPOSE:To attain the display of many characters by using a character generator ROM connected to a master processor unit MPU via a bus. CONSTITUTION:An MPU 1 is prepared together with a liquid crystal display LCD control part 2 including an LCD controller 3 and a RAM 4, an LCD 5, a character generator ROM 6, i.e., a KANJI (Chinese character) ROM storing the font data on KANJI, etc., and a RAM 7 including a screen information table 8. Furthermore a ROM 9 is added to store a program used for a prescribed process of the MPU 1 and a cursor address table 10, together with a host device 11 which outputs the character codes in response to the operation of keys of a keyboard 12. Thus various types of characters are displayed with use of the ROM 6 connected to the MPU 1 via a bus.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a liquid crystal dot matrix display system, and particularly to a liquid crystal dot matrix character display that can display a large number of characters while automatically controlling the cursor address. Regarding the method.

[Conventional technology]

In the conventional liquid crystal dot matrix character display system, as shown in FIG.
Character display) A character generator ROM 42 built into the control section 41 is used to display characters. In the figure, 43 is a RAM, 44 is a liquid crystal dot matrix controller, and 45 is an MPU (Master Process).
er Unit), 46 is an LCD.

[Problem to be solved by the invention]

Conventionally, as mentioned above, characters have been displayed using the character generator ROM 42 built into the LCD Il control section 41, which has caused the problem that only limited characters such as alphanumeric characters can be displayed. there were.

An object of the present invention is to enable display of a large number of characters.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a RAM in which each dot of an LCD corresponds to each bit one-to-one.
and an LCD controller that writes data to a designated address of the RAM and controls the brightness of each dot of the LCD according to the contents stored in the RAM, an MPU, and a bus that connects the MPU and the bus. a character generator ROM connected through the ROM, a screen information table in which a logical cursor address indicating the logical display position of the cursor is stored, and a cursor address in which the correspondence between the logical cursor address and the address in the RAM is stored. and a table, the MPU obtains information by referring to the font data corresponding to the character code read from the character generator ROM and the cursor address table by adding a character code indicating the character to be displayed on the LCD. The RAM address corresponding to the logical cursor address stored in the screen information table is given to the LCD controller, and the logical cursor address stored in the screen information table is used to indicate the next cursor display position. and save the RAM address corresponding to the logical cursor address stored in the screen information table and the data stored in the address, and save the font data indicating the RAM address and the cursor. ■,
In addition to the CD controller, a process of adding the saved data and the address of the RAM to the LCD controller after a predetermined period of time is performed at a predetermined cycle.

[For production]

By adding a character code indicating the character to be displayed on the LCD, the MPU corresponds to the font data corresponding to the character code obtained from the character generator ROM and the logical cursor address stored in the screen information table obtained from the cursor address table. Give the RAM address to the LCD controller. As a result, the LCD controller writes the font data given by the MPU to the RAM according to the address given by the MPU. Furthermore, when the MPU provides the font data and the RAM address to the LCD controller, it changes the logical cursor address stored in the screen information table to one indicating the next cursor display position. The MPU also saves the data stored in the RAM address corresponding to the logical cursor address stored in the screen information table, adds the RAM address and font data indicating the cursor to the LCD controller, and saves the data after a predetermined period of time. The process of adding the data and RAM address to the LCD controller is performed at predetermined time intervals.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, in which the MPUI
, an LCD @ Gobe two-color section 2CD5 consisting of an LCD controller 3 and a RAM 4, and a character generator ROM (
6, a RAM 7 in which a screen information table 8 is provided, and a ROM 9 in which a cursor address table 10 and a program for causing the MPUI to perform the processing shown in the flowcharts of FIGS. 2 and 3 are stored.
and a host device 11 that outputs a character code in response to key operations on a keyboard 12.

Figure 2 shows the MPU when displaying characters on LCD5.
FIG. 3 is a flowchart showing an example of processing of MPU 1 when performing automatic cursor address control.The operation of this embodiment will be described below with reference to each figure.

When the power is turned on, the MPUI starts the process shown in the flowchart in FIG. Step S1),
Next, initial information is set in the screen information table 8 provided in the RAM 7 (step S2). As shown in FIG. 2, the screen information table 8 includes an area 8-1 in which a screen code indicating which of the multiple screen formats to use is stored, and a logical cursor on the screen. An area 8-2 is provided in which a logical cursor address indicating the display position (for example, what character) of the MP is stored.
The UI stores the predetermined screen code and logical cursor address in the area 8-1.8-2 of the screen information table 8 by performing the process in step S2.

Thereafter, when the user operates the keyboard 12 to specify a character to be displayed on the LCD 5, the host device 11 sends a character display request including a character code corresponding to the character specified by the key operation to the MPUI.

When the MPUI receives a character display request from the host device 11, it buffers the character code included in the character display request in an internal queuing buffer by interrupt processing (step S9).

When the character code is buffered in the queuing buffer (if the determination result in step S3 is YES), the MPUI performs the process in step S4. In step S4, the character code buffered at the head of the queuing buffer is extracted, and an address in the Kanji ROMG corresponding to the extracted character code is generated. In the next step S5, font data is read from the kanji ROM 6 using the address generated in step S4, and in the next step S6, font data is read out from the kanji ROM 6 based on the contents of the screen information table 8 in the RAM 7 and the contents of the cursor address table 10 in the ROM 9. A physical cursor address (address of RAM 4 in LCD control unit 2) corresponding to the logical cursor address stored in area 8-2 is obtained. Here, as shown in FIG. 2, the cursor address table 10 includes areas 10 corresponding to n screen formats.
-1 to 10-n, and each area 10-1 to 10-n has areas 100-1 to 100-n storing screen codes corresponding to the screen format, logical cursor addresses and corresponding physical Areas 101-1 to 101-n in which cursor addresses are stored in pairs and areas 102-1 to 102n in which stoppers are stored are provided. That is, in step S6, the MPUI selects a screen code that is the same as the screen code stored in the area 8-1 of the screen information table 8 from among the areas 100-1 to 100-n where screen codes are stored. The area 100-j in which is stored is searched, and the areas 101-1 to
Area 10 corresponding to the area 100-j found above in -n
1-j, and in the area 8-2 of the screen information table 8 among the physical cursor addresses stored there, find the physical cursor address stored in pair with the stored logical cursor address. By performing the searching process, the physical cursor address corresponding to the logical cursor address stored in the area 8-2 of the screen information table 8 is obtained.

When the physical cursor address is obtained in step S6, the MPU 1 adds the font data sold in step S5 and the physical cursor address obtained in step S6 to the LCD control unit 2, and instructs the display of the font data. (Step S7). When the font data and physical cursor address are added from the MPU L, the LCD controller 3 in the LCD control unit 2 processes the added font data according to the added physical cursor address.
Write to AM4. Each focus point in the RAM 4 corresponds to each dot on the display screen of the LCD 5 on a one-to-one basis, and the LCD controller 3 controls the brightness of each dot on the LCD 5 according to the contents stored in the RAM 4. , the font data read in step S5 can be displayed at the position specified by the logical cursor address. When the process of step S7 is completed, MP
The UI increments the logical cursor address stored in the area fil of the screen information table 8 by +1 (step 3B), and then returns to the process of step S3.

Moreover, the MPUI starts the interrupt processing shown in the flowchart of FIG. 3 every time the interval timer times out, that is, every predetermined time, and first, in step Sll, it is determined whether or not it is an odd-numbered interrupt processing. to decide. Then, if it is determined that it is an odd-numbered interrupt process (step Sit
), the MPUI selects the physical cursor corresponding to the logical cursor address stored in the area 8-2 of the screen information table 8 based on the contents of the screen information table 8 and the contents of the cursor address table 10. The address, that is, the physical cursor address indicating the current position where the cursor should be displayed is obtained (step 512), and then the physical cursor address obtained in step S12 is saved in the internal memory, and the RAM 4 in the LCD control unit 2 is saved.
Step 5: Save the data stored at the physical cursor address obtained in step S12 in the internal memory.
13) Next, the physical cursor address and font data indicating the cursor saved in step S13 are added to the LCD control unit 2, and an instruction is given to display the cursor. Here, various types of font data can be considered as the font data indicating the cursor, but for example, if data indicating characters is stored at the physical cursor address obtained in step S12, the "1", 0", black and white The inverted data can be used as the font data indicating the cursor, and if the data indicating the character is not stored, the font data indicating a predetermined shape can be used as the font data indicating the cursor.Thus, the LCD control unit LC within 2
The D controller 3 writes font data indicating the cursor added from the MPUI to the RAM 4 according to the added physical cursor address.

As mentioned above, each bit of the RAM 4 has a one-to-one correspondence with each dot of the LCD 5, so by doing as described above, the area 8-- of the screen information table 8 is
The cursor is displayed at the position specified by the logical cursor address stored in 2.

Furthermore, if the judgment result in step Sll is NO,
That is, if it is determined that this is an even-numbered interrupt process, M
The PUL reads the saved data saved in the internal memory (step 515), then adds the saved data read in step 315 and the physical cursor address saved in step S13 to the LCD1tI control unit 2, and displays the saved data. (Step 516
). 1 in the LCD control section 2. , When the save data and physical cursor address are added from the MPUI, the CD controller 3 writes the added save data to the RAM 4 according to the added physical cursor address. As mentioned above, each bit of RAM 4 has a one-to-one correspondence with each dot of LCD 5, so by doing as described above, the save data, that is, the cursor display, is placed at the position specified by the logical cursor address. The previous data is displayed.

That is, by performing the processing of steps S12 to S14 for displaying the cursor at the position indicated by the logical cursor address stored in the area 8-2 of the screen information table 8 at predetermined time intervals, and the processing of steps 312 to S14. Step S15 of erasing the displayed cursor. S1
6 are performed alternately, so by keeping the above predetermined time short, it is possible to display the cursor only at the position indicated by the logical cursor address stored in the area 8-2 of the screen information table 80. can.

〔Effect of the invention〕

As explained above, since the present invention uses an external character generator ROM connected to the MPU via a bus, the built-in character generator R
It has the advantage of being able to display many types of characters compared to the conventional method using OM, and also allows each dot on the LCD to have a one-to-one correspondence with each bit in RAM and the logical display position of the cursor. A cursor address table is provided that stores the correspondence with the logical cursor addresses shown.
The cursor display position indicated by the logical cursor address is converted to a RAM address using the cursor address table, and the converted address is used to
Since the font data indicating the cursor is written in M, there is an effect that the cursor can be automatically controlled. In addition, since the above-mentioned functions are realized in a firmware environment on a general-purpose MPU, it has the effect of reducing the number of commands used by the user and increasing the versatility when using the liquid crystal dot matrix. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIGS. 2 and 3 are flowcharts showing an example of MPU processing, and FIG. 4 is a block diagram of a conventional example. In the figure, ■...MPU. 2...LCD control unit, 3...LCD controller, 4.7...RAM. 5...LCD. 6...Kanji ROM. 8...Screen information table, 9...ROM. 10... Cursor address table, 11... Host device, 12... Keyboard, 13... Bus.

Claims (1)

[Claims] A RAM in which each dot of an LCD corresponds to each bit on a one-to-one basis.
and an LCD controller that writes data to a designated address of the RAM and controls the brightness of each dot of the LCD according to the contents stored in the RAM, an MPU, and a bus that connects the MPU and the bus. a character generator ROM connected through the ROM, a screen information table in which a logical cursor address indicating the logical display position of the cursor is stored, and a cursor address in which the correspondence between the logical cursor address and the address in the RAM is stored. and a table, the MPU obtains information by referring to the font data corresponding to the character code read from the character generator ROM and the cursor address table by adding a character code indicating the character to be displayed on the LCD. The RAM address corresponding to the logical cursor address stored in the screen information table is given to the LCD controller, and the logical cursor address stored in the screen information table is used to indicate the next cursor display position. and save the RAM address corresponding to the logical cursor address stored in the screen information table and the data stored in the address, and save the font data indicating the RAM address and the cursor. L.C.
A liquid crystal dot matrix character display system, characterized in that, in addition to the D controller, a process of adding the saved data and the address of the RAM to the LCD controller after a predetermined period of time is performed at a predetermined period.