GS2971 Datasheet, PDF(93/148 Page) Semtech Corporation – 3Gb/s, HD, SD SDI Receiver, with Integrated Adaptive Cable Equalizer complete with SMPTE Audio and Video Processing

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GS2971 Datasheet, PDF (93/148 Pages) Semtech Corporation – 3Gb/s, HD, SD SDI Receiver, with Integrated Adaptive Cable Equalizer complete with SMPTE Audio and Video Processing

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minimum of 1.5ns (t0 in Figure 4-49) before the first clock edge to ensure proper

operation.

When the Auto-Increment bit is set LOW, each Command Word must be followed by

only one Data Word to ensure proper operation.

If the Auto-Increment bit is set HIGH, the following Data Word is written into the

address specified in the Command Word, and subsequent Data Words are written into

incremental addresses from the first Data Word. This facilitates multiple address writes

without sending a Command Word for each Data Word.

NOTE: The RSV bits in the GSPI command word can be set to zero as placeholder,

though these bits are not used.

4.20.2 Data Read or Write Access

During a read sequence (Command Word R/W bit set HIGH) serial data is transmitted or

received MSB first, synchronous with the rising edge of the serial clock SCLK. The Chip

Select (CS) signal must be set low a minimum of 1.5ns (t0 in Figure 4-49) before the first

clock edge to ensure proper operation. The first bit (MSB) of the Serial Output (SDOUT)

is available (t5 in Figure 4-50) following the last falling SCLK edge of the read Command

Word, the remaining bits are clocked out on the negative edges of SCLK.

NOTE 1: When several devices are connected to the GSPI chain, only one CS may be

asserted during a read sequence.

During a write sequence (Command Word R/W bit set LOW), a wait state of 37.1ns (t4 in

Figure 4-49) is required between the Command Word and the following Data Word. This

wait state must also be maintained between successive Command Word/Data Word

write sequences. When Auto Increment mode is selected (AutoInc = 1), the wait state

must be maintained between successive Data Words after the initial Command

Word/Data Word sequence.

During the write sequence, all Command and following Data Words input at the SDIN

pin are output at the SDOUT pin unchanged. When several devices are connected to the

GSPI chain, data can be written simultaneously to all the devices which have CS set

LOW.

MSB

LSB

D15

D14

D13

D12

D11

D10

Figure 4-48: Data Word Format

GS2971 3Gb/s, HD, SD SDI Receiver

Data Sheet

45898 - 2

September 2012

93 of 148

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