AS3900 datasheet(27/59 Pages) AMSCO

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AS3900

Data Sheet - Detail ed Description

The following chapter describes the permanent Pairing that is initiated by the Master. All other pairing procedures are described in an appropriate

application note.

Note: It i

s important that for the Pairing procedure all Timers need to be disabled. Set REG 0x02 to 0.

8.6.2 Master Initializes Pairing (wakeup) Procedure

Before any paring action could be started the MCU has to load the following configuration registers

Table 24. Configuration Registers

Client /

Master

Bank

Comments

The Pairing Master shows the pairing procedure that is initialized by the Master. The Sensors (=Clients) are set into receive mode. The Master

transmits a Wakeup Signal (OOK-Pattern) for one second. Afterwards the Sensors are activated and send after a random time a data frame with

5 bytes payload to tell the Master its ID. The random time is usually derived from the fixed programmed ID and calculated by the MCU of the

Sensor. The Master switches to receive mode after sending the Wakeup Signal, in order to listen for Sensor data. If data from a Client is

received, the ID is stored into the ID-Table (applied by the MCU of the Master). The Master sends a SYNC frame and waits for an

acknowledgement (ACKN). The Master RX stays on and waits for the next Sensor data. If all Sensors are permanently paired all nodes switch to

Standby Mode again.

The following sequence explains the operations that need to be done by the MCU at the Master and Client.

Master initiates permanent Pairing

Client is set to receive mode and listens during periodic time windows for a Wakeup Call form

the Master. The Master transmits the Wakeup Call in order to wakeup the Clients. After the

Wakeup and a random delay the Client starts the first transmission. The Master verifies the

received Client ID and compares it to the existing IDs in the ID-table. If the ID is new and the

CRC is correct, the ID is inserted. After a handshake with the Client (acknowledgement), both

nodes pass into Standby Mode again.

Temporary Pairing

An existing network data transmission is already established. A second Master wants to listen

to the data communication of a special Client. The second Master is set to receive mode and

listens for Clients that are transmitting data. New IDs are added to the ID-table and the timing

system is adopted (cycle time, bit rate …). The procedure is identical to “Master initiated

Pairing” except that no Wakeup call and no handshake are done.

Client

wakecyc

0x04<4:2>

Main

Wakeup detection interval time

wake_rx

0x00<2>

Main

Activates wakeup detection mode

Master

val_id

0x08… 0x1F

Main

List of allowed devices IDs to connect (or written via SDI after MCU

decision)

waketm

0x04<1:0>

Main

Wakeup call duration

Client

cyctim0

0x0C<7:5>

Shadow

Cycletime, period between two TX operations is only defined by the Client.

To be synchronized to the Master this information is included in the data

frame.

rndpt0

0x0C<4:0>

Shadow

Random pointer of part of the period between two TX operations. Is only

defined by the Client. To be synchronized to the Master this information is

included in the data frame.

TX_data

0x08… 0x1F

Main

Data in TX register will be appended to the ID and cycle time information.

Client payload data can be any information

Master/Client

bitrate

0x06<1:0>

Main

Defines data rate for the communication, need to be the same for Master

and Client

Table 23. Pairing Procedure

Pairing Procedures

Description

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