www.ams.com/LF-Receiver/AS3932

Revision 1.7

17 - 34

AS3932

Datasheet - Detailed Descr i p ti on

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 B8 defines the direct command while the last 8 bits are omitted. The Table 12

shows all possible direct commands:

All direct commands are explained below:

- clear_wake: clears the wake state of the chip. In case the chip has woken up (WAKE pin is high) the chip is set back to listening mode

- reset_RSSI: resets the RSSI measurement.

- trim_osc: starts the trimming procedure of the internal RC oscillator (see Figure 21)

- clear_false: resets the false wake-up register (R13<7:0>=00)

- preset_default: sets all register in the default mode, as shown in Figure 7

diagrams).

A CS toggling high-low-high indicates the end of the WRITE command after register has been written. The following example shows a write

command.

Figure 13. Writing of a Single Byte (falling edge sampling)

00

101

0

R10

00

101

1

R11

00

110

0

R12

00

110

1

R13

Table 12. List of Direct Commands

COMMAND_MODE

B13

B12

B11

B10

B9

B8

clear_wake

0

0

0

0

0

0

reset_RSSI

0

0

0

0

0

1

trim_osc

0

0

0

0

1

0

clear_false

0

00

01

1

preset_default

0

0

0

1

0

0

Table 11. SDI Command Structure

B13

B12

B11

B10

B9

B8

Read/Write register

CS

SCLK

SDI

0

0

A5

A4

A3

A2

A1

A0

D5

D4

D3

D2

D1

D0

D7

D6

X

X

SCLK rising

edge Data is

transfered from

µC

SCLK

falling edge

Data is

sampled

Data is moved

to Address

A5-A0

CS falling

edge signals

end of

WRITE Mode

Two leading

Zeros indicate

WRITE Mode