Data Sheet

ADT7320

Rev. 0 | Page 17 of 24

SERIAL INTERFACE

ADT7320

GND

SCLK

DOUT

DIN

CT

INT

10kΩ

10kΩ

PULL-UP

0.1µF

MICROCONTROLLER

CS

Figure 14. Typical SPI Interface Connection

The ADT7320 has a 4-wire serial peripheral interface (SPI). The

interface has a data input pin (DIN) for writing data to the device, a

data output pin (DOUT) for reading data back from the device,

and a serial data clock pin (SCLK) for clocking data into and out of

the device. A chip select pin (CS) enables or disables the serial

interface. CS is required for correct operation of the interface.

Data is clocked out of the

on the falling edge of SCLK,

and data is clocked into the device on the rising edge of SCLK.

ADT7320

SPI COMMAND BYTE

All data transactions on the bus begin with the master taking

CS from high to low and sending out the command byte. The

command byte indicates to the

whether the transaction

is a read or a write and provides the address of the register for the

data transfer.

shows the command byte.

ADT7320

Table 15

Table 15. Command Byte

C7

C6

C5

C4

C3

C2

C1

C0

0

R/W

Register address

0

0

0

Bit C7, Bit C2, Bit C1, and Bit C0 of the command byte must all be

set to 0 to successfully begin a bus transaction. The SPI interface

does not work correctly if a 1 is written into any of these bits.

Bit C6 is the read/write bit; 1 indicates a read, and 0 indicates

a write.

Bits[C5:C3] contain the target register address. One register can

be read from or written to per bus transaction.