AS39513 datasheet(16/108 Pages) AMSCO

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[v1-10] 2018-Apr-25

AS39513 − Detailed Description

Initializing the Chip

A virgin chip (not initialized) can be initialized either through

the SPI port or through RFID interface from a reader. Once the

battery voltage is applied to the VBAT pin or the supply voltage

is extracted from the RF field, the AS39513 boots up with the

default factory configuration. For battery powered devices it is

important that VBAT ramps up with tRAMP minimum to ensure

system EEPROM values are correctly loaded into the system

registers. This is valid for both 1.5V and 3V battery operation.

Within tIDLE after power is applied, the logging controller goes

to the IDLE state where it waits for configuration. Once all of

the configuration information has been written to the device

using write system block commands, the RFID “Set Mode”

command is used to place the AS39513 either into the WAIT

state or into the ACTIVE state directly. If in the WAIT state, a

timer or input action can move the device into the ACTIVE state.

Once in the ACTIVE state, the AS39513 will begin logging data

whenever a logging event occurs.

RESET Mode

Once the chip powers up, either from the battery or the RF field,

and the power is stable, the initialization process begins. At this

point, the controller logic will read specific EEPROM addresses

and load them into “shadow” registers.

During this phase the battery type will be determined by

checking System parameter BTYPE available in the EEPROM

field.

Two of the other EEPROM fields that will be read during this

phase are the System parameters WAKEMD (wakeup mode) and

ACTIVE (true if last state was ACTIVE). If both of these fields are

high, it means that the chip was reinitialized from a previous

ACTIVE mode and the restart condition flag ACTPOR will be set

to high.

If the restart condition is true (ACTPOR is high) then the

measurement pointers and counters are reloaded from the last

available state and the device returns to the ACTIVE mode.

If the restart condition is false (ACTPOR is low), the register

pointers and counters are initialized assuming that no

measurements have been made but the MEASCNT and

MEASPTR values in EEPROM will be retained, and the device

enters IDLE mode. This means that if for example the battery

voltage dropped during a logging event and caused a POR, the

chip would enter idle mode ie stop, but the MEASCNT and

MEASPTR values would be retained in EEPROM. If the mode is

subsequently changed to Active (i.e. logging is restarted), the

EEPROM MEASCNT and MEASPTR are zeroed. (The bit fields

ACTPOR, WAKEMD, and ACTIVE are further documented in the

Memory Map section).

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