AD6654SLASHPCB datasheet(60/88 Pages) AD

60 / 88 page

AD6654

Rev. 0 | Page 60 of 88

SERIAL PORT CONTROL

The AD6654 serial port allows all memory to be accessed

(programmed or readback) serially in one-byte words. Either

serial port or microport can be used (but not both) at any given

time. Serial port control is selected using the SMODE pin (0 =

microport, 1 = serial port). Two serial port modes are available.

An SPI-compatible port is provided as well as a SPORT. The

choice of SPI or SPORT mode is selected using the MODE pin

(0 = SPI, 1 = SPORT).

Each individual byte of serial data (address, instruction and

data) may be shifted in either MSB first or LSB first using the

MSBFIRST pin (1 = MSB first, 0 = LSB first). The serial chip

select (SCS) pin is brought low to access the device for serial

control. When the SCS pin is held high, serial programming is

inhibited.

HARDWARE INTERFACE

The pins described in Table 26 comprise the physical interface

between the user’s programming device and the serial port of

the AD6654. All serial pins are inputs except for SDO, which is

an open-drain output and should be pulled high by an external

pull-up resistor (suggested value 1 kΩ).

A complete read or write cycle requires a minimum of three

bytes to transfer, consisting of address word, instruction word,

and data-word(s). As many as 127 data-words can be

transferred during a block transfer cycle. All address,

instruction, and data-word(s) must be formatted LSB first or

MSB first to match the state of the MSBFIRST pin.

The first word for serial transfer is the internal register address.

In LSB first mode, the address is the lower-most address for the

block transfer (subsequent addresses are generated by internal

increment). In MSB first, the address is highest address for the

block transfer (subsequent addresses are generated by internal

decrement).

The second word of serial transfer contains a one-bit read/write

indicator (1 = read, 0 = write), and seven bits to define the

number of data bytes to be transferred (N). For a single data

byte transfer (N = 1); one byte is shifted into SDI for a write

transfer, or shifted out of SDO for a read transfer, and the cycle

is complete. For a block transfer, N write/read operations are

performed, and the internal register address increments

(MSBFIRST = 0) or decrements (MSBFIRST = 1) after each

data byte is clocked into SDI for a write operation, or after each

data byte is clocked out of SDO for a read operation.

Figure 61 to Figure 64 illustrate a three byte block transfer

through the serial port. Read and write operations with

MSBFIRST high and low are shown. Please note that the figures

show the sequence for write/read transfer, and actual data

should be shifted in or out based upon the status of the

MSBFIRST pin. The operation details are common to both SPI

and SPORT modes except for the use of framing signals and

timing. Individual mode details follow. In single byte transfer

mode, the count in the second byte would be reduced to one,

and the number of data bytes would be reduced to one.

Table 26. Serial Port Pins

Function

SCLK

Serial Clock in Both SPI and SPORT Modes. Should have a rise/fall time of 3 ns max.

MSBFIRST

Indicates whether the first bit shifted in or out of the serial port is the MSB (1) or LSB (0) for both instruction and data-

words. Also indicates if the first instruction word (address) is a block start or a block end for multiple byte transfers. This

pin also controls the functionality when programming indirectly addressed registers.

STFS

Serial Transmit Frame Sync in SPORT Mode. STFS is not used in SPI mode.

SRFS

Serial Receive Frame Sync in SPORT Mode. SRFS is not used in SPI mode.

SDI

Serial Data Input in Both Modes. Serial data is clocked in on the rising edge of SCLK.

SDO

Serial Data Output in Both Modes. Serial data is clocked out on the rising edge of SCLK.

SCS

Active-Low Serial Chip Select in Both Modes.

SMODE

Serial Mode. Part is programmed through the serial port when this pin is high.

MODE

Mode Pin. Selects between SPI (0) and SPORT (1) modes.

AD6654/PCB Datenblatt(PDF) 60 Page - Analog Devices

AD6654/PCB Datenblatt(HTML) 60 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 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88

Datenblatt Download

Link URL