MAX6953 Maxim Integrated Products, MAX6953 Datasheet - Page 9

• 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

read-after-write verification, reset the command byte's
address because the stored byte address generally is
autoincremented after the write (Table 4).
If the MAX6953 is operated on a 2-wire interface with
multiple masters, a master reading the MAX6953
should use a repeated start between the write, which
sets the MAX6953's address pointer, and the read(s)
that takes the data from the location(s). This is because
it is possible for master 2 to take over the bus after
master 1 has set up the MAX6953's address pointer but
before master 1 has read the data. If master 2 subse-
quently changes the MAX6953's address pointer, then
master 1's delayed read may be from an unexpected
location.
Address autoincrementing allows the MAX6953 to be
configured with the shortest number of transmissions
by minimizing the number of times the command byte
needs to be sent. The command address or the font
pointer address stored in the MAX6953 generally incre-
ments after each data byte is written or read (Table 4).
The MAX6953 uses eight digit registers to store the char-
acters that the user wishes to display on the four 5
LED digits. These digit registers are implemented with
two planes of 4 bytes, called P0 and P1. Each LED digit
is represented by 2 bytes of memory, 1 byte in plane P0
Figure 7. Command Byte Received
Figure 8. Command and Single Data Byte Received
S
Command Address Autoincrementing
HOW CONTROL BYTE AND DATA BYTE MAP INTO
2-Wire Interfaced, 2.7V to 5.5V, 4-Digit 5
S
Operation with Multiple Masters
COMMAND BYTE IS STORED ON RECEIPT OF STOP CONDITION
MAX6953's REGISTERS
SLAVE ADDRESS
_______________________________________________________________________________________
ACKNOWLEDGE FROM MAX6953
SLAVE ADDRESS
R/W
ACKNOWLEDGE FROM MAX6953
0
Digit Registers
A
D15
R/W
D14
D13
0
ACKNOWLEDGE FROM MAX6953
✕
COMMAND BYTE
D12
Matrix LED Display Driver
7
A
D11
D15
and the other in plane P1. The digit registers are mapped
so that a digit’s data can be updated in plane P0, or
plane P1, or both planes at the same time (Table 5).
If the blink function is disabled through the Blink Enable
Bit E (Table 10) in the configuration register, then the
digit register data in plane P0 is used to multiplex the
display. The digit register data in P1 is not used. If the
blink function is enabled, then the digit register data in
both plane P0 and plane P1 are alternately used to mul-
tiplex the display. Blinking is achieved by multiplexing
the LED display using data planes P0 and P1 on alter-
nate phases of the blink clock (Table 11).
The data in the digit registers does not control the digit
segments directly. Instead, the register data is used to
address a character generator, which stores the data of
a 128-character font (Table 15). The lower 7 bits of the
digit data (D6 to D0) select the character from the font.
The most-significant bit of the register data (D7) selects
whether the font data is used directly (D7 = 0) or
whether the font data is inverted (D7 = 1). The inversion
feature can be used to enhance the appearance of
bicolor displays by displaying, for example, a red char-
acter on a green background.
The display blinking facility, when enabled, makes the
driver flip automatically between displaying the digit
register data in planes P0 and P1. If the digit register
data for any digit is different in the two planes, then that
D10
D14
D9
D8
D13
COMMAND BYTE
ACKNOWLEDGE FROM MAX6953
A
D12
D7
D11
D6
D10
D5
ACKNOWLEDGE FROM MAX6953
AUTOINCREMENT MEMORY WORD ADDRESS
D4
1 BYTE
DATA BYTE
D9
Display Blink Mode
D3
D8
D2
D1
A
D0
P
A
✕
P
7
9