Main Frame (acces to all the site)

Dot-matrix liquid crystal display (LCD)

• x-character, x-line TN liquid crystal display of 5 x 7 dot matrix + cursor
• Duty ratio 1/16
• Character generator ROM for 192 characters types
  (character font: 5 x 7 dot matrix)
• Character generator RAM for eight character types (program write)
  (character font: 5 x 7 dot matrix)
• 80 x 8 bit display data RAM (80 characters maximum)
• Interface with four-bit and eight-bit MPUs possible
• Display data RAM and character generator RAM readable from MPU
• Many instruction functions
  Clear Display, Cursor Home, Display ON/OFF, Cusor ON/OFF, Display Character Blink, Cursor Shift and Display Shifts
• Built-in oscilator circuit
• +5 V single power supply
• CMOS process
• operating temperature range: 0° C to 50° C

2. Terminal Functions

Table 1. Terminal functions

3. Basic Operations

3.1 Registers

    The controler has two kinds of eight-bit registers: the instruction register (IR) and the data register (DR). They are selected by the register select (RS) signals as shown in Table 2.
    The IR store instruction codes such as Display Clear and Cursor Shift, and the addres information of display data RAM (DD RAM) and character generator RAM (CG RAM). They can be writen from the MPU, but cannot be read to the MPU.
    The DR temporarily stores data to be written into DD RAM or CG RAM, or read from DD RAM or CG RAM. When data written into DD RAM or CG RAM from the MPU, the data in the DR is automatically writen into DD RAM or CG RAM by internal operation. However, when data is read from DD RAM or CG RAM, the necesary data addres is writen into the IR. The specified data is read out to the DR and then the MPU reads it from the DR. After the read operation, the next adress is set and DD RAM or CG RAM data at the addres is read into thr DR for the next read operation.

Table 2. Register selection

3.2 Busy flag (BF)

    The flag indicate whether the module is ready to accept the next instruction. As show in table 2, the signal is output to DB7 if RS = 0 and R/-W = 1. If the value is 1, the module is working internally and the instruction cannot be accepted. If the vlue is 0, the next instruction can be written. Therefore, the flag statusneeds to be checked before executing an instruction. If an instruction is executed without checking the flag status, wait for more than the execution time show in Table 5. Instruction Outline.

3.3 Address counter (AC)

    The counter specifies an address writen when data is written into DD RAM or CG RAMand the data stored in DD RAM or CG RAM is read out. If an Address Set instriction (for DD RAM or CG RAM) is written in the IR, the addresinformation is transferred from the IR to the AC. When display data is written into or read from DD RAM or CG RAM, the AC is automatically incremented or decremented by one according to the Entry Mode Set. The contents of the AC are output to DB0 to DB6 as show in Table 2 if RS = 0 and R/-W = 1.

3.4 Display data RAM (DD RAM)

    DD RAM has a capacity of up to 80 x 8 bits and stores display data of 80 eight-bit characters codes. Some storage areas of DD RAM which are not used for display can be used as general data RAM.
    The DD RAM address and the displayy digits of the LCD panel correspond as follows.
    If the display is shifted, DD RAM address 00h to 27h are displayed in digits from the first line and 40h to 67h in the second line (from a LCD with two line).

3.5 Character generator ROM (CG ROM)

   Character generator ROM generates 192 types of 5 x 7 dot matrix character patterns from eight-bit character codes.
   Table 3 shows the correspondence between the CG ROM character codes and characters patterns. 

Table 3.

3.6 Character generator RAM (CG RAM)

   CG RAM is used to create character patterns freely by programming. Eight types of character patterns can be written.
   Table 4 shows the character patterns created from CG RAM addresses and data. To display a created character pattern, the character code in the left column of the table is written into DD RAM corresponding to the display position (digit). The area not used for display are available as general data RAM.

Notes:

• In CG RAM data, 1 corresponds to Selection and 0 to Non-selection on the display.
• Character code bits 0 to 2 and CG RAM address bits 3 to 5 correspond with each other (three bits, eight types).
• CG RAM address bits 0 to 2 specify a line position for a character pattern. Line 8 of a character pattern is cursor position where the logical sum of the cursor and CG RAM data is displayed. Set the data of line 8 to 0 to display the cursor. If the data is changed to 1, one bit lights, regardless of the cursor.
• The character pattern column position correspond to CG RAM data bits 0 to 4 and bit 4 comes to the left end. CG RAM data bits 5 to 7 are not displayed but can be used as general data RAM.
• When reading a character pattern from CG RAM, set to 0 all of character code bits 4 to 7. Bits 0 to 2 determine which pattern will be read out. Since bit 3 is not valid, 00h and 08h select the same character.

4. Timing Characteristics

4.1 Write timing characteristics

4.2 Read timing characteristics

5. Instructions Outline

Nota:

5. Instruction Details

   Instruction                                 Code

                             RS  R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
                             ==  === === === === === === === === ===
Clear Display                 0   0   0   0   0   0   0   0   0   1

Return Home                   0   0   0   0   0   0   0   0   1   *

Entry Mode Set                0   0   0   0   0   0   0   1  I/D  S

Display ON/OFF                0   0   0   0   0   0   1   D   C   B

Cursor and Display Shift      0   0   0   0   0   1  S/C R/L  *   *

Function Set                  0   0   0   0   1   DL  N   F   *   *

Set CG RAM address            0   0   0   1   A   A   A   A   A   A

Set DD RAM address            0   0   1   A   A   A   A   A   A   A

Read busy flag and address    0   1   BF  A   A   A   A   A   A   A

Write data to CG or DD RAM    1   0   D   D   D   D   D   D   D   D

Read data from CG or DD RAM   1   1   D   D   D   D   D   D   D   D

Notes
* means 0 or 1 have no effect

Where execution times are given as A / B