HDSP-253X HP [Agilent(Hewlett-Packard)], HDSP-253X Datasheet - Page 10

• Manufacturer Part Number: HDSP-253X
• Description: Eight Character 5 mm Smart Alphanumeric Display
• Manufacturer: HP [Agilent(Hewlett-Packard)]

UDC RAM and UDC Address
Register
Figure 3 shows the logic levels
needed to access the UDC RAM
and the UDC Address Register.
The UDC Address Register is
eight bits wide. The lower four
bits (D
of the 16 UDC locations. The
upper four bits (D
used. Once the UDC address has
been stored in the UDC Address
Register, the UDC RAM can be
accessed.
To completely specify a 5 x 7
character requires eight write
cycles. One cycle is used to store
the UDC RAM address in the UDC
Address Register. Seven cycles
are used to store dot data in the
UDC RAM. Data is entered by
rows. One cycle is needed to
access each row. Figure 4 shows
the organization of a UDC
character assuming the symbol to
be stored is an “F.” A
to select the row to be accessed
and D
the row dot data. The upper three
bits (D
significant bit) corresponds to the
right most column of the 5 x 7
matrix and D
bit) corresponds to the left most
column of the 5 x 7 matrix.
Flash RAM
Figure 5 shows the logic levels
needed to access the Flash RAM.
The Flash RAM has one bit
associated with each location of
the Character RAM. The Flash
input is used to select the Flash
RAM. Address lines A
ignored. Address lines A
used to select the location in the
Flash RAM to store the attribute.
D
flash attribute. D
the attribute and D
removes the attribute.
0
is used to store or remove the
0
0
-D
5
-D
-D
4
3
7
are used to transmit
) are used to select one
) are ignored. D
4
(most significant
0
4
= “1” stores
0
-D
= “0”
0
7
3
-A
) are not
-A
2
0
4
-A
are used
are
0
2
(least
are
Figure 3. Logic Levels to Access a UDC Character.
Figure 4. Data to Load ""F'' into the UDC RAM.
When the attribute is enabled
through bit 3 of the Control Word
and a “1” is stored in the Flash
RAM, the corresponding
character will flash at approxi-
10
mately 2 Hz. The actual rate is
dependent on the clock frequency.
For an external clock the flash
rate can be calculated by dividing
the clock frequency by 28,672.