SLB128B NSC [National Semiconductor], SLB128B Datasheet - Page 16

• Manufacturer Part Number: SLB128B
• Description: Transmitter with built-in scaler for LVDS Display Interface (LDI)
• Manufacturer: NSC [National Semiconductor]

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DS90C2501 Pin Description
Two-Wire Serial Communication
Interface Description
There are two register sets on DS90C2501. One set is for
controlling the input and output blocks as shown below, and
one set is for controlling the scaler which is not shown on this
datasheet. Both register sets are accessible by the host
system through the Two-Wire Serial Communication Inter-
face. The DS90C2501 operates as a slave on the Serial Bus,
so the SCL line is an input (no clock is generated by the
DS90C2501) and the SDA line is bi-directional. DS90C2501
has a 7-bit slave address. The address bits are controlled by
the state of the address select pins A2, A1 and A0, and are
set by connecting these pins to ground for a LOW, (0) , to
V
Therefore, the complete slave address is:
and is selected as follows:
CC
MSB
A6
3V pin for a HIGH, (1).
A2
0
0
0
0
1
1
1
1
Address Select Pin
A5
State
A1
0
0
1
1
0
0
1
1
A4
A0
A3
0
1
0
1
0
1
0
1
TABLE 1. scaler is powered down under these conditions
provided that PD
No input clock is
PD bit issued by
BYPASS bit is 0
issued by host.
BYPASS bit
A2
bit is 1 and
(A6:A3 are hardwired
DUAL pin
detected
Bus Slave Address
/PD pin
DS90C2501 Serial
host
A6:A0 binary
to "0111")
0111000
0111001
0111010
0111011
0111100
0111101
0111110
0111111
A1
(Continued)
LSB
A0
scaler is On
L or
NO
H
1
16
1
0
⁄
2
V
CC
The DS90C2501 latches the state of the address select pins
during the first read or write on the Serial Bus. Changing the
state of the address select pins after the first read or write to
any device on the Serial Bus will not change the slave
address of the DS90C2501.
Communicating with the DS90C2501 Control Registers
All registers are predefined as read only, or read and write.
The Serial Interface will always attempt to detect if a LCD
panel/monitor is connected.
A Write to the DS90C2501 will always include the slave
address byte, data register address byte, a data byte.
A Read from the DS90C2501 can take place either of two
ways:
1. If the location latched in the data register addresses is
2. If the data register address needs to be set, then a slave
The data byte has the most significant bit first. At the end of
a read, the DS90C2501 can accept either Acknowledge or
No Acknowledge from the Master (No Acknowledge is typi-
cally used as a signal for the slave that the Master has read
its last byte).
Serial Bus Protocol
The DS90C2501 slave state machine does not require an
internal clock, and supports only byte read and write. Page
mode is not supported. The 7-bit binary address is
“0111A
A6:A3 are hardwired internally to "0111"
correct , then the read can simply consist of a slave
address byte, followed by retrieving the data byte.
address byte, data register address will be sent first,
then the master will repeat start, send the slave address
byte and receive data byte to accomplish a read.
2
L or
A
scaler is OFF
1
A
1
0
⁄
”, where A
2
V
YES
CC
L
0
1
or VCC
2
A
1
A
0
are pin programmable and