AD9530 datasheet(24/41 Pages) AD

24 / 41 page

AD9530

Data Sheet

Rev. 0 | Page 24 of 41

Read

If the instruction word indicates a read operation, the next

N × 8 SCLK cycles clock out the data starting from the address

specified in the instruction word. N is the number of data bytes

read. The readback data is driven to the pin on the falling edge

and must be latched on the rising edge of SCLK. Blank registers

are not skipped over during readback.

A readback operation takes data from either the serial control

port buffer registers or the active registers, as determined by

SPI Instruction Word (16 Bits)

The MSB of the 16-bit instruction word is R/W, which indicates

whether the instruction is a read or a write. The next 15 bits are

the register address (A14 to A0), which indicates the starting

that, because there are no registers that require more than

13 address bits, A14 and A13 are ignored and treated as zeros.

SPI MSB/LSB First Transfers

The AD9530 instruction word and payload can be MSB first or

LSB first. The default for the AD9530 is MSB first. The LSB first

mode can be set by writing a 1 to Register 0x000, Bit 6 and Bit 1.

Immediately after the LSB first bit is set, subsequent serial

control port operations are LSB first.

Address Ascension

If the address ascension bit (Register 0x000, Bit 5 and Bit 2) = 0,

the serial control port register address decrements from the

specified starting address toward Address 0x0000.

If the address ascension bit (Register 0x0000, Bit 5 and Bit 2) = 1,

the serial control port register address increments from the

starting address toward Address 0x0FF. Reserved addresses are

not skipped during multibyte input/output operations;

therefore, write the default value to a reserved register and 0s to

unmapped registers. Note that it is more efficient to issue a new

write command than to write the default value to more than

two consecutive reserved (or unmapped) registers.

Table 19. Streaming Mode (No Addresses Skipped)

Address Ascension

Stop Sequence

Increment

0x0000 … 0x1FFF

Decrement

0x1FFF … 0x0000

Table 20. Serial Control Port, 16-Bit Instruction Word

MSB

LSB

I15

I14

I13

I12

I11

I10

R/W

A14

A13

A12

A11

A10

SCLK DON'T CARE

SDIO

A12

A13

A14

R/W

A11 A10 A9

A6 A5

A3 A2

D7 D6

D2 D1

D6 D5

D3 D2

DON'T CARE

16-BIT INSTRUCTION HEADER

Figure 25. Serial Control Port Write—MSB First, Address Decrement, Two Bytes of Data

SCLK

SDIO

SDO

16-BIT INSTRUCTION HEADER

A12

A13

A14

R/W

A11 A10

A9 A8 A7 A6 A5 A4 A3 A2 A1 A0

DON'T CARE

DON'T

CARE

D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0

Figure 26. Serial Control Port Read—MSB First, Address Decrement, Four Bytes of Data

DON'T CARE

A14

A13

A12

A11

A10

A9A8A7

A6A5

D4D3

D2D1D0

DON'T CARE

R/W

tDS

tDH

tHIGH

tLOW

tCLK

SCLK

SDIO

Figure 27. Timing Diagram for Serial Control Port Write—MSB First

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