AS3900 datasheet(25/59 Pages) AMSCO

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AS3900

Data Sheet - Detail ed Description

8.5 Wakeup Procedure

In general the Wakeup is introduced in order to handle two different challenges:

Wakeup Clients that are in Standby Mode. Clients in standby consume a small amount of power from the battery

Exchange actual time code (Cycle time, random pointer) and synchronize all Clients with the Master

The Client (Master) is set to Wakeup receive mode for short time with a long wakeup interval. Master (Client) transmits long enough wakeup

sequence to catch the receiving window of the Client (Master) or the Client is set to Wakeup receive mode for long time to catch the transmitted

Master Wakeup sequences. If the Client (Master) receives a Wakeup sequence the link manager triggers the wake_call interrupt.

The Link Manager needs to be instructed via the direct COMMANDS and via REGISTER settings. The MCU is informed of the current status via

INTERRUPTS, which need to be read out as soon as an external interrupt on the IRQ line appears.

8.5.1 Wakeup Receive Mode

The Wakeup Receive Window can be set to:

Sampling: The Wakeup Receive Window is turned on for a fixed time of 250µs and turned off again for the remaining cycle time. The cycle

time for the receive window can be set by the wakecyc bits in REG 0x04<2:4>. The ON interval itself is fixed to 250µs. The current con-

sumption is defined by the ON to OFF ratio of the Wakeup receiver.

8.5.2 Wakeup Transmit Mode

Transmitting a Wakeup Signal means that the PA applies an OOK Signal (On Off Keying), in order to wakeup the Master (Client). The OOK

pattern is a 27MHz signal that is ON OFF modulated with 96kHz. The following parameters for this OOK signal can be configured:

Wakeup Transmitter On time: The Wakeup call can be applied between 125ms up to 1s in REG 0x04<1:0>.

Longwake TX: The Wakeup call can be applied as long as the longwake_tx bit is set in REG 0x04<5>.

The Wakeup transmit mode shows a Wakeup procedure initialized by the Master. The Client samples for the Wakeup signal periodically. The

figure shows the Wakeup procedure.

Figure 20. Wakeup Transmit Mode

Table 22. Wakeup Procedure Initialized by the Master

Step

Master

Client

Client wakeup receiver listens during periodic time windows. This

action is started by MCU with the command WAKE_RX_ON. The

duration of wakeup listening is hardwired to 250µs and the wakeup

listening cycle-time is defined by the wakecyc bits, REG 0x04<4:2>.

The Master starts the wakeup call with the command

WAKE_TX The duration of the call is defined by the waketm

bits, REG 0x04<1:0> (for MCU defined wakeup call duration

the long wake_tx bit, REG 0x04<5> has to be used).

MASTER

CLIENT1

WAKEUP

RECEIVE

250µs

wakecyc

wake_call

LISTEN

WAKE_RX_ON

WAKE_TX

TRANSMIT

waketm

Receive = 1s

longwake_tx set

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