MAX6953 Maxim Integrated Products, MAX6953 Datasheet - Page 14

• Manufacturer Part Number: MAX6953
• Description: 2-Wire Interfaced/ 2.7V to 5.5V/ 4-Digit 5 x 7 Matrix LED Display Driver
• Manufacturer: Maxim Integrated Products

2-Wire Interfaced, 2.7V to 5.5V, 4-Digit 5
Matrix LED Display Driver
Table 15. Character Map
14
LSB
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
MSB
______________________________________________________________________________________
x000
RAM00
RAM01
RAM02
RAM03
RAM04
RAM05
RAM06
RAM07
RAM08
RAM09
RAM10
RAM11
RAM12
RAM13
RAM14
RAM15
RAM16
RAM17
RAM18
RAM19
RAM20
RAM21
RAM22
RAM23
x001
x010
x011
x100
x101
x110
x111
When global digit data clear is set, the digit data for
both planes P0 and P1 for all digits are cleared during
the acknowledge (Table 13).
When the configuration register is read, the P bit
reflects the state of the blink output pin at that time
(Table 14).
The font is a 5
ROM, and 24 user-definable characters. The selection
from the total of 128 characters is represented by the
lower 7 bits of the 8-bit digit registers. The most-signifi-
cant bit, shown as x in the ROM map, is zero to light
LEDs as shown by the black segments in Table 15, and
1 to display the inverse.
The character map follows the Arial font for 96 charac-
ters in the range 0x0101000 through x1111111. The
first 32 characters map the 24 user-definable positions
(RAM00 to RAM23), plus eight extra common charac-
ters in ROM.
The 24 user-definable characters are represented by
120 entries of 7-bit data, five entries per character, and
are stored in MAX6953's internal RAM.
The 120 user-definable font data entries are written and
read through a single register, address 0x05. An
autoincrementing font address pointer in the MAX6953
indirectly accesses the font data. The font address
pointer can be written, setting one of 120 addresses
between 0x00 and 0xF7, but cannot be read back. The
font data is written to and read from MAX6953 indirect-
ly, using this font address pointer. Unused font loca-
tions can be used as general-purpose scratch RAM,
bearing in mind that the font registers are only 7 bits
wide, not 8.
Table 16 shows how the single user-defined font regis-
ter 0x05 is used to set the font address pointer, write
font data, and read font data. A read action always
returns font data from the font address pointer position.
A write action sets the 7-bit font address pointer if the
MSB is set, or writes 7-bit font data to the font address
pointer position if the MSB is clear.
The font address pointer autoincrements after a valid
access to the user-definable font data. Auto-
incrementing allows the 120 font data entries to be writ-
ten and read back very quickly because the font point-
er address need only be set once. When the last data
location 0xF7 is written, the font address pointer autoin-
crements to address 0x80. If the font address pointer is
Global Clear Digit Data (R Data Bit D5) Format
Blink Phase Readback (P Data Bit D7) Format
Character Generator Font Mapping
✕
7 matrix comprising 104 characters in
User-Defined Fonts
✕
7