AS3933 datasheet(29/64 Pages) AMSCO

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[v1-08] 2015-Sep-02

AS3933 − Detailed Description

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.

Figure 29 shows all possible direct commands:

Figure 29:

List of 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.

• Calib_RCosc: starts the trimming procedure of the internal

RC oscillator (see page 29).

• 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 24.

• Calib_RCO_LC: calibration of the RC-oscillator with the

external LC tank (see page 31).

Writing of Data to Addressable Registers (WRITE Mode). The

SPI is sampled at the falling edge of SCLK (as shown in the

following 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.

R18

R19

COMMAND_MODE

B13

B12

B11

B10

clear_wake

reset_RSSI

trim_osc

clear_false

preset_default

Calib_RCO_LC

B13

B12

B11

B10

Read/Write Register

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