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AS3930

Data Sheet - D e t a i l e d D e s c r i p t i o n

8.3.1.3 Serial Data Interface (SDI)

This 4-wire interface is used by the Microcontroller (µC) to program the AS3930. The maximum clock operation frequency of the SDI is 2 MHz.

Note:

SDO is set to tristate if CS is low. In this way more than one device can communicate on the same SDO bus.

SDI Command Structure

To program the SDI the CS signal has to go high. A SDI command is made up by a two bytes serial command and the data is sampled on the

falling edge of SCLK. The Table 9 shows how the command looks like, from the MSB (B15) to LSB (B0). The command stream has to be sent to

the SDI from the MSB (B15) to the LSB (B0).

The first two bits (B15 and B14) define the operating mode. There are three modes available (write, read, direct command) plus one spare (not

used), as shown in Table 10.

In case a write or read command happens the next 5 bits (B13 to B9) define the register address which has to be written respectively read, as

shown in Table 11.

R12<4:0>

Reserved

R13<7:0>

F_WAK

WR

False wakeup register

Table 8. Serial Data Interface (SDI) pins

Name

Signal

Signal Level

Description

CS

Digital Input with pull down

CMOS

Chip Select

SDI

Digital Input with pull down

CMOS

Serial Data input for writing registers, data to

transmit and/or writing addresses to select

readable register

SDO

Digital Output

CMOS

Serial Data output for received data or read

value of selected registers

SCLK

Digital Input with pull down

CMOS

Clock for serial data read and write

Table 9. SDI Command Structure

Mode

Register address / Direct Command

Register Data

B15

B14

B13

B12

B11

B10

B9

B8

B7

B6

B5

B4

B3

B2

B1

B0

Table 10. SDI Command Structure

B15

B14

Mode

00

WRITE

0

1

READ

1

0

NOT ALLOWED

1

1

DIRECT COMMAND

Table 11. SDI Command Structure

B13

B12

B11

B10

B9

B8

Read/Write register

000

000

R0

000

001

R1

000

010

R2

000

011

R3

Table 7. Default Values of Registers

Register

Name

Type

Default

Value

Description