DS90UR907Q-Q1 Datasheet, PDF (21/35 Pages) Texas Instruments – 24-Bit Color FPD-Link to FPD-Link II Converter

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Programming (continued)
DS90UR907Q-Q1
SNLS316G – SEPTEMBER 2009 – REVISED DECEMBER 2015
HOST
SCL
SDA
1.8V
V_DDIO
4.7k
4.7k
10k
ID[X]
R_ID
DS90UR907Q
SCL
SDA
To other
Devices
Figure 21. Serial Control Bus Connection
The third pin is the ID[x] pin. This pin sets one of four possible device addresses. Two different connections are
possible. The pin may be pulled to V_DD (1.8 V, NOT V_DDIO)) with a 10-kΩ resistor. Or a 10-kΩ pullup resistor (to
V_DD1.8 V, NOT V_DDIO)) and a pulldown resistor of the recommended value to set other three possible addresses
may be used. See Table 5.
The Serial Bus protocol is controlled by START, START-Repeated, and STOP phases. A START occurs when
SCL transitions Low while SDA is High. A STOP occurs when SDA transition High while SCL is also HIGH. See
Figure 22.
SDA
SCL
S
START condition, or
START repeat condition
P
STOP condition
Figure 22. Start and Stop Conditions
To communicate with a remote device, the host controller (master) sends the slave address and listens for a
response from the slave. This response is referred to as an acknowledge bit (ACK). If a slave on the bus is
addressed correctly, it Acknowledges (ACKs) the master by driving the SDA bus low. If the address doesn't
match a device's slave address, it Not-acknowledges (NACKs) the master by letting SDA be pulled High. ACKs
also occur on the bus when data is being transmitted. When the master is writing data, the slave ACKs after
every data byte is successfully received. When the master is reading data, the master ACKs after every data
byte is received to let the slave know it wants to receive another data byte. When the master wants to stop
reading, it NACKs after the last data byte and creates a stop condition on the bus. All communication on the bus
begins with either a Start condition or a Repeated Start condition. All communication on the bus ends with a Stop
condition. A READ is shown in Figure 23 and a WRITE is shown in Figure 24.
If the Serial Bus is not required, the three pins may be left open (NC).
Resistor
RID kΩ
0.47
2.7
8.2
Open
Table 5. ID[x] Resistor Value – DS90UR907Q
Address 7'b
7b' 110 1001 (h'69)
7b' 110 1010 (h'6A)
7b' 110 1011 (h'6B)
7b' 110 1110 (h'6E)
Address 8'b
0 appended (WRITE)
8b' 1101 0010 (h'D2)
8b' 1101 0100 (h'D4)
8b' 1101 0110 (h'D6)
8b' 1101 1100 (h'DC)
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