TMF0064

COMMAND LEVELS

ROM

COMMANDS

MEMORY

COMMANDS

READ ROM

MATCH ROM

SEARCH ROM

SKIP ROM

RESUME

OVERDRIVE SKIP ROM

OVERDRIVE MATCH ROM

COMMANDS

WRITE SCRATCHPAD

READ SCRATCHPAD

COPY SCRATCHPAD

READ MEMORY

EXTENDED READ MEMORY

Figure 6-7. Command Structure for the TMF0064

6.5.2 Initialization

The host always begins the transaction with the TMF0064 (target) through an initialization process. The

initialization process consists of two pulse: RESET and PRESENCE. The host generates the RESET pulse,

while the TMF0064 responds with the PRESENCE pulse. The host resets the TMF0064 by driving the SDQ bus

low for at least 480μs. The PRESENCE pulse alerts the host that there are one or more TMF0064 devices on

the bus that are ready for operation.

6.5.3 ROM Commands

After the host detects the presence of one or more target devices on the SDQ bus, the host can send one

of the 8-bit ROM function commands that the TMF0064 supports depending on the use case scenario. This

section describes the scenarios where each of the ROM command can be issued. See Figure 6-7 for list of these

commands.

6.5.3.1 READ ROM Command [33h]

The READ ROM command sequence (as Figure 6-8 shows) starts with the host generating the RESET pulse of

at least 480μs. The device responds with a PRESENCE pulse. Next, the host continues by issuing the READ

ROM command, 33h, and then reads back the 56-bit Family code and serial number followed by the 8-bit CRC

using the READ signaling (see the READ and WRITE signals section) during the data frame. The host can issue

the READ ROM command only if there is a single TMF0064 device on the SDQ bus. If the host issues the

command when there are more than 1 target device on the SDQ bus, then data collision occurs since all the

target devices try to respond to the host. The host can identify the data collision by comparing the CRC from the

READ ROM sequence with the computed CRC which results in a mismatch.

0

1

1

0

0

0

1

1

CRC (1 BYTE)

Reset

and

Presence

Signals

Read ROM (33h)

Family Code and Identification

Number (7 BYTES)

Figure 6-8. READ ROM Sequence

6.5.3.2 MATCH ROM Command [55h]

When there are multiple targets on the bus, the host uses the Match ROM command, 55h, to select a specific

target device when the family code and identification number is known. The host issues the Match ROM

command followed by the family code, serial number, and CRC byte. The target device that matches the 64-bit

serial ID is selected and available to perform subsequent memory function commands. The MATCH ROM

command can also be used with a single TMF0064 on the bus.

www.ti.com

TMF0064

SLVSJQ6 – SEPTEMBER 2025

Copyright © 2025 Texas Instruments Incorporated

Submit Document Feedback

13

Product Folder Links: TMF0064