MAX6952
4-Wire Interfaced, 2.7V to 5.5V,
4-Digit 5
✕
7 Matrix LED Display Driver
12 ______________________________________________________________________________________
32 characters map the 24 user-definable positions
(RAM00 to RAM23), plus eight extra common charac-
ters in ROM.
User-Defined Fonts
The 24 user-definable characters are represented by
120 entries of 7-bit data, five entries per character, and
are stored in the MAX6952'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 MAX6952
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 the MAX6952 indi-
rectly, using this font address pointer. Unused font
locations can be used as general-purpose scratch
RAM, bearing in mind that the font registers are only 7
bits wide, not 8.
Table 15 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
set to an out-of-range address by writing data in the
0xF8 to 0xFF range, then address 0x80 is set instead
(Table 16).
Table 17 shows the user-definable font pointer base
addresses.
Blink timing counters are unaffected. P X R 0 E B X S
Digit data for both planes P0 and P1 are unaffected. P X 0 T E B X S