3

I²C interface protocol

3.1

Compliance and features

The ST33TPHF2XI2C TPM device is compliant with [PTP 2.0 r1.04], with the following options:

•

Bus speed must be in the range of 10 kbits to 400 kbits.

•

10-bit slave addressing is not supported.

•

Slave address reconfiguration is supported in the range of 0x08 to 0x77.

•

Clock stretching is not used.

•

1.8 V and 3.3 V are supported.

•

Five localities are supported.

•

The minimum guard time is 20 µs.

•

Supported interrupts are “Locality Change” and “Data Available”.

•

The burst count is dynamic, with a maximum burst of 1936 bytes.

•

Data checksum is supported.

3.2

Register space addresses

The I²C TPM registers are used to map the FIFO TPM 2.0 interface to TPM 2.0 implementations where I²C is the

host interface. The table below lists those registers.

Table 2. I²C TPM register overview

TPM-specific registers

Address

Name

Length

Description

Master access

0x00

TPM_LOC_SEL

1

Selection of the locality of the current access.

Read/Write

0x01-0x03 Reserved

N/A

Read operations return 0xFF.

N/A

0x04

TPM_ACCESS

1

Used to gain ownership of the TPM for this

particular locality.

Read/Write

0x05-0x07 Reserved

N/A

Read operations return 0xFF.

N/A

0x08-0XB

TPM_INT_ ENABLE

4

Enables specific interrupts and has the global

enable feature.

Read/Write

0x0C-0x0F Reserved

N/A

Read operations return 0xFF.

N/A

0x10-0x13 TPM_INT_ STATUS

4

Shows which interrupt has occurred.

Read/Write

0x14-0x17 TPM_INT_ CAPABILITY

4

Provides information about the interrupts

supported by this particular TPM device.

Read-only

0x18-0x1B TPM_STS

4

Contains general status details.

Read/Write

0x1C-0x1F Reserved

N/A

Read operations return 0xFF.

N/A

0x20

TPM_HASH_END

1

This signals the end of the hash operation.

Only available when locality 4 is selected.

Write-only

0x21-0x23 Reserved

N/A

Read operations return 0xFF.

N/A

0x24

TPM_DATA_FIFO

TPM_STS

(burst-count)

Buffer to exchange the data for commands and

responses with the host. For locality 4, this is

also aliased to TPM_HASH_DATA.

Read/Write

0x25-0x27 Reserved

N/A

Read operations return 0xFF.

N/A

0x28

TPM_HASH_START

1

This signals the start of the hash operation.

Only available when locality 4 is selected(1).

Write-only

0x29-0x2F Reserved

N/A

Read operations return 0xFF.

N/A

0x30-0x33

TPM_I2C_ INTERFACE_

CAPABILITY

4

I²C Interface Capability register.

Read-only

ST33TPHF2XI2C

I²C interface protocol

DS14167 - Rev 1

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