AD9511-VCOSLASHPCB datasheet(42/60 Pages) AD

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AD9511

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writing to Register 5Ah<0> = 1b. This update bit is self-clearing

(it is not required to write 0 to it to clear it). Since any number

of bytes of data can be changed before issuing an update

command, the update simultaneously enables all register

changes since any previous update.

Phase offsets or divider synchronization is not effective until a

SYNC is issued (see the Single-Chip Synchronization section).

Read

If the instruction word is for a read operation (I15 = 1b), the

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

specified in the instruction word, where N is 1 to 4 as

determined by W1:W0. The readback data is valid on the falling

edge of SCLK.

The default mode of the AD9511 serial control port is

unidirectional mode; therefore, the requested data appears on

the SDO pin. It is possible to set the AD9511 to bidirectional

mode by writing the SDO enable register at 00h<7> = 1b. In

bidirectional mode, the readback data appears on the SDIO pin.

A readback request reads the data that is in the serial control

port buffer area, not the active data in the AD9511’s actual

control registers.

SCLK

SDIO

SDO

CSB

UPDATE

REGISTERS

5Ah <0>

SERIAL

CONTROL

PORT

AD9511

CORE

Figure 45. Relationship Between Serial Control Port Register Buffers and

Control Registers of the AD9511

The AD9511 uses Address 00h to Address 5Ah. Although the

AD9511 serial control port allows both 8-bit and 16-bit

instructions, the 8-bit instruction mode provides access to five

address bits (A4 to A0) only, which restricts its use to the

address space 00h to 01F. The AD9511 defaults to 16-bit

instruction mode on power-up. The 8-bit instruction mode

(although defined for this serial control port) is not useful for

the AD9511; therefore, it is not discussed further in this data

sheet.

THE INSTRUCTION WORD (16 BITS)

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

whether the instruction is a read or a write. The next two bits,

W1:W0, indicate the length of the transfer in bytes. The final 13

bits are the addresses (A12:A0) at which to begin the read or

write operation.

For a write, the instruction word is followed by the number of

bytes of data indicated by Bits W1:W0, which is interpreted

according to Table 20.

Table 20. Byte Transfer Count

Bytes to Transfer

A12:A0

: These 13 bits select the address within the register map

that is written to or read from during the data transfer portion

of the communications cycle. The AD9511 does not use all of

the 13-bit address space. Only Bits A6:A0 are needed to cover

the range of the 5Ah registers used by the AD9511. Bits A12:A7

must always be 0b. For multibyte transfers, this address is the

starting byte address. In MSB first mode, subsequent bytes

increment the address.

MSB/LSB FIRST TRANSFERS

The AD9511 instruction word and byte data may be MSB first

or LSB first. The default for the AD9511 is MSB first. The LSB

first mode may be set by writing 1b to Register 00h<6>. This

takes effect immediately (since it only affects the operation of

the serial control port) and does not require that an update be

executed. Immediately after the LSB first bit is set, all serial

control port operations are changed to LSB first order.

When MSB first mode is active, the instruction and data bytes

must be written from MSB to LSB. Multibyte data transfers in

MSB first format start with an instruction byte that includes the

data bytes must follow in order from high address to low

address. In MSB first mode, the serial control port internal

address generator decrements for each data byte of the

multibyte transfer cycle.

When LSB_First = 1b (LSB first), the instruction and data bytes

must be written from LSB to MSB. Multibyte data transfers in

LSB first format start with an instruction byte that includes the

multiple data bytes. The serial control port internal byte address

generator increments for each byte of the multibyte transfer

cycle.

The AD9511 serial control port register address decrements

from the register address just written toward 0000h for

multibyte I/O operations if the MSB first mode is active

(default). If the LSB first mode is active, the serial control port

toward 1FFFh for multibyte I/O operations.

Unused addresses are not skipped during multibyte I/O

operations; therefore, it is important to avoid multibyte I/O

operations that would include these addresses.

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