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AS3932

8.3.3.1 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.

The last 8 bits are the data that has to be written respectively read. A CS toggle high-low-high terminates the command mode.

If a direct command is sent (B15-B14=11) the bits from B13 to B9 defines the direct command while the last 8 bits are omitted. The Table 12

shows all possible direct commands:

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

000

100

R4

000

101

R5

000

110

R6

000

111

R7

001

000

R8

001

001

R9

001

010

R10

001

011

R11

001

100

R12

001

101

R13

Table 12. List of Direct Commands

COMMAND_MODE

B13

B12

B11

B10

B9

B8

clear_wake

0

00000

reset_RSSI

0

00001