AD9958SLASHPCB datasheet(30/40 Pages) AD

30 / 40 page

AD9958

Rev. 0 | Page 30 of 40

tDV

SCLK

SDIO

SDO (SDIO_2)

SYMBOL

DEFINITION

MIN

DATA VALID TIME

12ns

Figure 41. Timing Diagram for Data Read for Serial I/O Port

INSTRUCTION BYTE DESCRIPTION

The instruction byte contains the following information.

Table 25.

MSB

LSB

R/Wb

1x = don’t care bit.

Bit 7 of the instruction byte (R/Wb) determines whether a read

or write data transfer occurs after the instruction byte write. A

logic high indicates a read operation. Logic 0 indicates a write

operation.

Bits 4 to 0 of the instruction byte determine which register is

accessed during the data transfer portion of the

communications cycle. The internal byte addresses are

generated by the AD9958.

SERIAL I/O PORT PIN DESCRIPTION

Serial Data Clock (SCLK). The serial clock pin is used to

synchronize data to and from the internal state machines of the

AD9958. The maximum SCLK toggle frequency is 200 MHz.

Chip Select (CS). The chip select pin allows more than one

AD9958 device to be on the same set of serial communications

lines. The chip select is an active low enable pin. Defined SDIO

inputs go to a high impedance state when CS is high. If CS is

driven high during any communications cycle, that cycle is

suspended until CS is reactivated low. The CS pin can be tied

low in systems that maintain control of SCLK.

Serial Data I/O (SDIO_0:3). Of the four SDIO pins, only the

SDIO_0 pin is a dedicated SDIO pin. SDIO_1:3 can also be used

to RU/RD the output amplitude. Bits <2:1> in the channel select

pins. See the Serial I/O Modes of Operation section for more

information.

SERIAL I/O PORT FUNCTION DESCRIPTION

Serial Data Out (SDO). The SDO function is available in single-

bit (3-wire) mode only. In SDO mode, data is read from the

SDIO_2 pin for protocols that use separate lines for trans-

mitting and receiving data (see Table 26 for pin configuration

options). Bits <2:1> in the CSR register (Register 0x00) control

the configuration of this pin. The SDO function is not available

in 2-bit or 4-bit serial I/O modes.

SYNC_I/O. The SYNC_I/O function is available in 1-bit and

2-bit modes. SDIO_3 serves as the SYNC_I/O pin when this

function is active. Bits <2:1> in the CSR register (Register 0x00)

control the configuration of this pin. Otherwise the SYNC_I/O

function is used to synchronize the I/O port state machines

without affecting the addressable register contents. An active

high input on the SYNC_I/O (SDIO_3) pin causes the current

communication cycle to abort. After SDIO_3 returns low

(Logic 0), another communication cycle can begin, starting

with the instruction byte write. The SYNC_I/O function is not

available in 4-bit serial I/O mode.

MSB/LSB TRANSFER DESCRIPTION

The AD9958 serial port can support both MSB-first or LSB-first

data formats. This functionality is controlled by CSR <0> in the

channel select register (CSR). MSB-first is the default mode.

When CSR <0> is set high, the serial port is in LSB-first format.

The instruction byte must be written in the format indicated by

CSR <0>. That is, if the AD9958 is in LSB-first mode, the

instruction byte must be written from LSB to MSB. If the

AD9958 is in MSB-first mode (default), the instruction byte

must be written from MSB to LSB.

Example Operation

To write the Function Register 1 (FR1) in MSB-first format,

apply an instruction byte of MSB > 00000001 < LSB, starting

with the MSB. From this instruction, the internal controller

recognizes a write transfer of three bytes starting with the MSB,

Bit <23>, in the FR1 address (Register 0x01). Bytes are written

on each consecutive rising SCLK edge until Bit<0> is

transferred. Once the last data bit is written, the I/O

communication cycle is complete and the next byte is

considered an instruction byte.

To write the Function Register 1 (FR1) in LSB-first format,

apply an instruction byte of MSB > 00000001 < LSB, starting

with the LSB. From this instruction, the internal controller

recognizes a write transfer of three bytes, starting with the

LSB <0> in the FR1 address (0x01). Bytes are written on each

consecutive rising SCLK edge until Bit <23> is transferred.

Once the last data bit is written, the I/O communication cycle is

complete and the next byte is considered an instruction byte.

AD9958/PCB датащи(PDF) 30 Page - Analog Devices

AD9958/PCB датащи(HTML) 30 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

датащи скачать

ссылки URL