ADT7516 datasheet(39/44 Pages) AD

39 / 44 page

ADT7516/ADT7517/ADT7519

Rev. A | Page 39 of 44

Any number of bytes of data can be transferred over the serial

bus in one operation, but it is not possible to mix read and write

in one operation because the type of operation is determined at

the beginning and cannot subsequently be changed without

starting a new operation.

The I2C address set up by the ADD pin is not latched by the

device until after this address has been sent twice. On the eighth

SCL cycle of the second valid communication, the serial bus

address is latched in. This is the SCL cycle directly after the

device has seen its own I2C serial bus address. Any subsequent

changes on this pin will have no effect on the I2C serial bus

address.

Writing to the ADT7516/ADT7517/ADT7519

Depending on the register being written to, there are two

different writes for the ADT7516/ADT7517/ADT7519. It is not

possible to do a block write to this part, i.e., no I2C auto-

increment.

Writing to the Address Pointer Register for a

Subsequent Read

To read data from a particular register, the address pointer

the correct address must be written to the address pointer

in Figure 60. The write operation consists of the serial bus

address followed by the address pointer byte. No data is written

to any of the data registers. A read operation is then performed

to read the register.

Writing Data to a Register

All registers are 8-bit registers, so only one byte of data can be

written to each register. Writing a single byte of data to one of

these read/write registers consists of the serial bus address, the

data register address written to the address pointer register,

followed by the data byte written to the selected data register.

This is illustrated in Figure 61. To write to a different register,

another start or repeated start is required. If more than one byte

of data is sent in one communication operation, the addressed

been sent.

Reading Data from the ADT7516/ADT7517/ADT7519

Reading data from the ADT7516/ADT7517/ADT7519 is done

in a 1-byte operation. Reading back the contents of a register is

shown in Figure 62. The register address had previously been

set up by a single-byte write operation to the address pointer

pointer register again to set up the relevant register address.

Thus, block reads are not possible, i.e., no I2C auto-increment.

SPI Serial Interface

The SPI serial interface of the ADT7516/ADT7517/ADT7519

consists of four wires: CS, SCLK, DIN, and DOUT. The CS is

used to select the device when more than one device is con-

nected to the serial clock and data lines. The CS is also used to

distinguish between any two separate serial communications

(see Figure 67 for a graphical explanation). The SCLK is used to

clock data in and out of the part. The DIN line is used to write to

the registers, and the DOUT line is used to read data back from

the registers. The recommended pull-up resistor value is

between 500 Ω and 820 Ω.

The part operates in slave mode and requires an externally

applied serial clock to the SCLK input. The serial interface is

designed to allow the part to be interfaced to systems that

provide a serial clock that is synchronized to the serial data.

There are two types of serial operations, read and write. Com-

mand words are used to distinguish read operations from write

operations. These command words are given in Table 67.

Address auto-increment is possible in SPI mode.

Table 67. SPI Command Words

Write

Read

90h (1001 0000)

91h (1001 0001)

R/W

SCL

SDA

FRAME 1

SERIAL BUS ADDRESS BYTE

FRAME 2

ADDRESS POINTER REGISTER BYTE

ACK. BY

ADT7516/ADT7517/ADT7519

ACK. BY

ADT7516/ADT7517/ADT7519

STOP BY

MASTER

START BY

MASTER

Figure 60. I2C—Writing to the Address Pointer Register to Select a Register for a Subsequent Read Operation

ADT7516 Datasheet(PDF) 39 Page - Analog Devices

ADT7516 Datasheet(HTML) 39 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

Datasheet Download

Link URL