ADATE304BBCZ datasheet(36/51 Pages) AD

36 / 51 page

ADATE304

Data Sheet

Rev. C | Page 36 of 51

READ OPERATION

The read operation is a two-stage operation. First, a word is shifted

in, specifying which register to read. CS is deasserted for three

clock cycles, and then a second word is shifted in to obtain the

readback data. This second word can be either another operation or

an NOP address.

If another operation is shifted in, it must shift in at least eight bits of

data to read back the previous specified data. The NOP address can

be used for this read if there is no need to read/write another

recommended that the NOP address be used for all reads.

Any register read that is fewer than 16 bits has zeros filled in the

top bits to make it a 16-bit word.

READ INSTRUCTION

NOP

READ DATA

SCLK

INPUT

SDIN

INPUT

SDOUT

OUTPUT

INPUT

NOTES

1. X = DON’T CARE.

Figure 71. SPI Read Overview

DATA[15:0], VALUE IS A DON’T CARE

CH[1]

R/W

CH[0]

ADDR[4] ADDR[3] ADDR[2]

ADDR[1] ADDR[0]

SCLK

INPUT

SDIN

INPUT

SDOUT

OUTPUT

INPUT

NOTES

1. X = DON’T CARE.

Figure 72. SPI Read—Details of Read Request

DATA[15:0], VALUE IS A DON’T CARE

CH[1]

RDATA[2]

RDATA[1]

RDATA[15] RDATA[14]

RDATA[0]

R/W = 1

ADDR[4:0] = 0x00 (NOP)

CH[0]

SCLK

INPUT

SDIN

INPUT

SDOUT

OUTPUT

INPUT

NOTES

1. RDATA IS THE REGISTER VALUE BEING READ.

2. X = DON’T CARE.

Figure 73. SPI Read—Details of Read Out

ADATE304BBCZ Datasheet(PDF) 36 Page - Analog Devices

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