ATECC608A datasheet(62/81 Pages) MICROCHIP

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Table 7-2. Word Address Values

Name

Value

Description

Reset

0x00

Reset the address counter. The next I2C read or write transaction will start with the beginning of

the I/O buffer.

Sleep

(Low-power)

0x01

The ATECC608A-TNGLoRaWAN goes into the low-power Sleep mode and ignores all

subsequent I/O transitions until the next Wake flag. The entire volatile state of the device is reset.

Idle

0x02

The ATECC608A-TNGLoRaWAN goes into the Idle mode and ignores all subsequent I/O

transitions until the next Wake flag. The contents of TempKey, MessageDigestBuffer, and

Alternate Key registers are retained.

Command

0x03

Write subsequent bytes to sequential addresses in the input command buffer that follow previous

writes. This is the normal operation.

Reserved

0x04 – 0xFF

These addresses should not be sent to the device.

7.2.2

I2C Synchronization

It is possible for the system to lose synchronization with the I/O port on the ATECC608A-TNGLoRaWAN, perhaps

due to a system Reset, I/O noise, or other conditions. Under this circumstance, the ATECC608A-TNGLoRaWAN may

not respond as expected, may be asleep, or may be transmitting data during an interval when the system is

expecting to send data. To resynchronize, the following procedure can be followed:

To ensure an I/O channel Reset, the system must send the standard I2C software Reset sequence, as follows:

• A Start bit condition

• Nine cycles of SCL, with SDA held high by the system pull-up resistor

• Another Start bit condition

• A Stop bit condition

It should then be possible to send a read sequence, and if synchronization completes properly, the

ATECC608A-TNGLoRaWAN will ACK the device address. The device may return data or may leave the bus

floating (which the system will interpret as a data value of 0xFF) during the data periods.

If the device does ACK the device address, the system should reset the internal address counter to force the

ATECC608A-TNGLoRaWAN to ignore any partial input command that may have been sent. This can be

accomplished by sending a write sequence to word address 0x00 (Reset), followed by a Stop condition.

If the device does not respond to the device address with an ACK, then it may be asleep. In this case, the

system must send a complete Wake token and wait tWHI after the rising edge. The system may then send

another read sequence, and if synchronization is complete, the device will ACK the device address.

If the device still does not respond to the device address with an ACK, then it may be busy executing a

command. The system must wait the longest tEXEC (max) and then send the read sequence, which will be

acknowledged by the device.

7.3

Sleep Sequence

Upon completion of the use of the ATECC608A-TNGLoRaWAN by the system, the system should issue a sleep

sequence to put the device into Low-Power mode. This sequence consists of the proper device address followed by

the value of 0x01 as the word address followed by a Stop condition. This transition to the Low-Power state causes a

complete reset of the device’s internal command engine and input/output buffer. It can be sent to the device at any

time when it is awake and not busy.

7.4

Idle Sequence

If the total sequence of required commands exceeds tWATCHDOG, then the device will automatically go to sleep and

lose any information stored in the volatile registers. This action can be prevented by putting the device into Idle mode

prior to completion of the watchdog interval. When the device receives the Wake token, it will then restart the

Watchdog Timer and execution can be continued.

ATECC608A-TNGLoRaWAN

I2C Interface

Complete Datasheet

DS40002154B-page 62

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