ATSHA204A datasheet(11/93 Pages) MICROCHIP

11 / 93 page

Bit 0:

0 = Single-Wire Interface Mode.

1= I2C interface Mode.

2.1.2.2

I2C_Address

I2C Mode I2C_Enable<0> = 1

Bits 7 – 1:

I2C device address

Bit 3:

TTL Enable (Dual purpose bit)

Part of I2C Address and set’s the threshold level.

0= Input level uses a fixed reference.

1 = Input level uses the VCC as reference.

Bit 0:

Ignored.

Single-Wire Mode I2C_Enable<0> = 0

Bits 7–4:

Ignored.

Bit 3:

TTL Enable

0= Input level uses a fixed reference.

1 = Input level uses the VCC as reference.

Bits 2–0:

Ignored.

2.1.2.3

CheckMacConfig

This byte applies only to the CheckMac, Read and Write commands:

•

Read and Write: CheckMacConfig<0> controls Slots 0 and 1, CheckMacConfig<1> controls Slots

2 and 3 and so on. Any encrypted Read or Write command fails if the value in

TempKey.SourceFlag does not match the corresponding bit in this byte. This byte is ignored for

clear text reads and writes.

•

CheckMac: CheckMacConfig<0> controls slot 1, CheckMacConfig<1> controls Slot 3 and so on.

The copy function can only be enabled if the CheckMacSource value corresponding to the target

slot matches the value of Mode bit 2 of the CheckMac command. The command fails if Mode bit 2

does not match TempKey.SourceFlag, so this is equivalent to requiring the corresponding bit in this

byte to match TempKey.SourceFlag.

2.1.2.4

OTP Mode

0xAA (Read-only mode) = When OTP zone is locked, writes are disabled and reads of all words are

permitted.

0x55 (Consumption mode) = Writes to the OTP zone when the OTP zone is locked causes the bits to

transition only from a one to a zero. Reads of all words are permitted.

0x00 (Legacy mode) = When OTP zone is locked, writes are disabled, reads of Words 0 and 1 and 32-

byte reads are disabled.

All other modes are reserved.

ATSHA204A

Device Organization

DS40002025A-page 11

ATSHA204A Datasheet(PDF) 11 Page - Microchip Technology

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