LMH0318_15 Datasheet, PDF (24/57 Pages) Texas Instruments – LMH0318 3 Gbps HD/SD SDI Reclocker with Integrated Cable Driver

LMH0318
SNLS508 – SEPTEMBER 2015
8.3.7.8.2 SPI Daisy Chain Write Read Example
In Figure 14 and Figure 15, the following occurs at the end of the first transaction:
• Write 0x22 to register 0x01 in Device 3
• Latch the data from register 0x34 in Device 2
• Write 0x44 to register 0x76 in Device 1
MOSI
(Host)
0 0x01 0x22 1 0x34 0xFF 0 0x76 0x44
Figure 14. SPI Daisy Chain Write Read First Frame Illustration
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MOSI
(Host)
MISO
(Host)
1 0xFF 0xFF 1 0xFF 0xFF 1 0xFF 0xFF
0 0x01 0x22 1 0x34 0x3C 0 0x76 0x44
Figure 15. SPI Daisy Chain Write Read second Frame Illustration
8.3.7.8.2.1 SPI Daisy Chain Length of Daisy Chain Illustration
A useful operation for the Host may be to detect the length of the daisy-chain. This is a simple matter of shifting
in a series of known data values (0x7F, 0xAA) in the example in Figure 16. After N+1 writes, the known data
value will begin to appear on the Host's MISO pin.
MOSI
(Host)
MISO
(Host)
1 0x7F 0xAA 1 0x7F 0xAA 1 0x7F 0xAA
x xx
xx x xx
xx 1 0x7F 0xAA
Figure 16. MOSI (Host)
8.3.8 Power-On Reset
The LMH0318 has an internal power-on reset (PoR) circuitry which initiates a self-clearing reset after the power
is applied to the VDD pins.
8.4 Device Functional Modes
The LMH0318 features can be programmed via SPI, or SMBus interface. LMH0318 Device Configuration
describes detailed operation using SPI, or SMBus interface.
8.5 Programming
For more information on device programming, See LMH0318 Programming Guide (SNLU183). Register
initialization is required at power-up or after reset. See Initialization Set Up
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