MAX6850 MAXIM [Maxim Integrated Products], MAX6850 Datasheet - Page 9

• Manufacturer Part Number: MAX6850
• Description: 4-Wire Interfaced, 7-, 14-, and 16-Segment Alphanumeric Vacuum-Fluorescent Display Controller
• Manufacturer: MAXIM [Maxim Integrated Products]

The MAX6850 uses 48 character registers (48/1 mode)
(Table 4) or 96 character registers (96/2 mode) (Table
5) to store the 7-, 14-, and 16-segment characters
(Table 6). Each digit is represented by 1 byte of memo-
ry. The data in the character registers does not control
the character segments directly. Instead, the register
data is used to address a character generator, which
stores the data of the 128-character font (Table 7). The
lower 7 bits of the character data (D6 to D0) select a
character from the font table. The most significant bit
(MSB) of the register data (D7) controls the DP seg-
ment of the digit; it is set to light the DP, cleared to
leave it unlit.
4-Wire Interfaced, 7-, 14-, and 16-Segment Alpha-
Table 1. Display Modes
Table 2. Register Address Map
48/1 mode
96/2 mode
No-Op
VFBLANK polarity
Intensity
Grids
Configuration
User-defined fonts
Output map
Display test and device ID
PUMP register
Filament duty cycle
PHASE1
PHASE2
PORT0
PORT1
Shift limit
Cursor
Factory reserved. Do not write to register.
DISPLAY
MODE
numeric Vacuum-Fluorescent Display Controller
48 digits, each with a DP segment and a cursor
segment
96 digits, each with a DP segment and a cursor
segment
_______________________________________________________________________________________
REGISTER
MAXIMUM NO. OF DIGITS
Character Registers
D15
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
X
D14
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
MAXIMUM NO. OF
ANNUNCIATORS
The character registers address maps are shown in
Table 4 (48/1 mode) and Table 5 (96/2 mode).
In 48/1 mode, the character registers use a single
address range 0x20 to {0x20 + g}, where g is the value
in the grids register (Table 26). The 48/1 mode upper
address limit, when g is 0x2F, is therefore 0x4F. The
address range 0x50 to 0x7F is used for annunciator
data in 48/1 mode.
In 96/2 mode, the character registers use two address
ranges. The first row’s address range is 0x20 to
{0x20 + g}. The second row’s address range is 0x50 to
{0x50 + g}. Therefore, in 96/2 mode, the character reg-
isters are only one contiguous memory range when a
48-grid display is used.
4 per digit
D13
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
None
COMMAND ADDRESS
D12
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
D11
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
MAXIMUM NO.
OF GRIDS
48 grids
D10
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
D9
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
DIGITS COVERED
BY EACH GRID
2 digits per grid
1 digit per grid
D8
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
CODE
0x0A
0x0B
0x0C
0x0D
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
0x0E
0x0F
0x10
HEX
9