
2–7
SCD5580/5581/5582/5583/5584
The following explains how to format the serial data to be
loaded into the display. The user supplies a string of bit
mapped decoded characters. The contents of this string is
shown in Figure 9a. Figure 9b shows that each character
consist of six 8 bit words. The rst word encodes the display
character location and the succeeding ve bytes are row
data. The row data represents the status (On, Off) of individ-
ual column LEDs. Figure 9c shows that each that each 8 bit
word is formatted to include a three bit Operational Code
(OPCODE) dened by bits D7–D5 and ve bits (D4–D0) rep-
resenting Column Data, Character Address, or Control Word
Data.
Figure 9d shows the sequence for loading the bytes of data.
Bringing the LOAD line low enables the serial register to
accept data. The shift action occurs on the low to high transi-
tion of the serial data clock (SDCLK). The least signicant bit
(D0) is loaded rst. After eight clock pulses the LOAD line is
brought high. With this transition the OPCODE is decoded.
The decoded OPCODE directs D4-D0 to be latched in the
Character Address register, stored in the RAM as Column
data, or latched in the Control Word register. The control IC
requires a minimum 600 ns delay between successive byte
loads. As indicated in Figure 9a, a total of 528 bits of data
are required to load all eight characters into the display.
Row Address Register bits, D7–D5 (Table 3), direct the Col-
umn Data bits, D4–D0 (Table 3) to specic RAM location.
Table 1 shows the Row Address for the example character
“D.” Column data is written and read asynchronously from the
200 bit RAM. Once loaded the internal oscillator and charac-
ter multiplexer reads the data from the RAM. These charac-
ters are row strobed with column data as shown in Figures 8
and 9. The character strobe rate is determined by the internal
or user supplied external MUX Clock and the IC’s
÷320
counter.
Table 1. Character “D”
Opcode
Column Data
HEX
D7
D6
D5
D4
D3
D2
D1
D0
Row 0
000111101E
Row 1
0011000131
Row 2
0101000151
Row 3
0111000171
Row 4
100111109E
Figure 9a–d. Loading serial character data
Character 0
Character 1
Character 2
Character 3
Character 4
Character 5
Character 6
Character 7
528 Clock Cycles, 105.6 s
Example: Serial Clock = 5 MHz, Clock Period = 200 ns
Time between LOADS
LOAD
Serial
Clock
DATA
Clock
Period
t
0
D0
D1
D2
D3
D4
D5
D6
D7
11 Clock Cycles, 2.2 s
Time
Between
Loads
OPCODE
Character Address
OPCODE
Column Data
D0
C4
D1
C3
D2
C2
D3
C1
D4
C0
Character 0
Address
Row 0 Column
Data
66 Clock Cycles, 13.2 s
Row 1 Column
Data
Row 2 Column
Data
Row 3 Column
Data
Row 4 Column
Data
D0
0
D1
0
D2
0
D3
0
D4
0
D5
1
D6
0
D7
0
D5 D6 D7
a.
b.
c.
d.
11 Clock Cycles, 2.2 s
600 ns(min.)
Time
Between
Loads
600 ns(min.)