PT6314_10 Datasheet, PDF (18/42 Pages) Princeton Technology Corp – Dot Character VFD Controller/Driver IC

PT6314
5.3 CHARACTER GENERATOR ROM (CGROM)
The CGROM is the Read Only Memory (ROM) responsible for the generation of 5 x 8 dots character patterns from 8-bit
character codes. A total of up to 240 character patterns can be generated. Please note that Character Codes -- 00H to
07H are allocated to the CGRAM.
5.4 CHARACTER GENERATOR RAM (CGRAM)
The Character Generator RAM (CGRAM) allows the user to reconstruct the character patterns from 8-bit by software
programming. Eight character patterns can be written and constructed using 5 x 8 dots. Areas that are not used for
display purposes may be used as general data RAM.
The table below shows the relationship between the CGRAM Address, Character Code (DDRAM) and the 5x7 (cursor
included) dot character patterns (CGRAM).
Character Code (DDRAM Data)
D7 D6 D5 D4 D3 D2 D1 D0
High Order Bit
Low Order Bit
0000X000
0000X001
CGRAM Address
A5 A4 A3 A2 A1 A0
High Order Bit
Low Order Bit
000000
001
010
011
100
101
110
111
001000
001
010
011
100
101
110
111
D7 D6 D5
High Order Bit
X
X
X
X
X
X
CGRAM Data
D4 D3 D2 D1 D0
Low Order Bit
1
1
1
1
1
1
0
0
0
1
1
0
0
0
1
1
1
1
1
1
1
0
0
0
0
1
0
0
0
0
1
0
0
0
0
0
0
0
0
0
1
1
1
1
1
0
0
1
0
0
0
0
1
0
0
0
0
1
0
0
0
0
1
0
0
0
0
1
0
0
0
0
1
0
0
0
0
0
0
0
Character Pattern No. 1
Cursor Position
Character Pattern No. 2
Cursor Position
0
0
0
0
X
1
1
1
11
1
00
0X
X
X
0
1
1
1
1
001
1
0
0
0
0
010
1
0
0
0
0
011
1
0
0
0
0 Character Pattern No. 8
100
1
0
0
0
0
101
1
0
0
0
0
110
0
1
1
1
1
111
1
1
1
1
1 Cursor Position
Notes:
1. X= Irrelevant
2. Character Code Bits 0 to 2 correspond to the CGRAM Address Bits 3 to 5 (3 bits: 8 type).
3. CGRAM Address Bits 0 to 2 determine the character pattern line position. The 8th line is the cursor
position and its display is formed by a logical OR with the cursor. Maintain the 8th line data,
corresponding to the cursor display position at 0 as the cursor display. If the 8th line data is “1” all
the 1 bits will light up the 8th line regardless of the cursor presence.
4. Character pattern row position corresponds to the CGRAM data bits 0 to 4. (bit 4 is positioned at the
left)
5. The CGRAM character patterns are selected when the character code bits 4 to 7 are all set to “0”.
The Character Code Bit 3 is irrelevant, the “P” Display shown above (Character Pattern No. 1) can
be selected by either character Code 00H or 07H.
6. When CGRAM Data=“1” the Display is turned ON. When CGRAM data=“0” display is turned OFF.
V1.5
18
October 2009