TMP1827 datasheet(29/68 Pages) TI

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Host Sends Reset

Pulse

TMP18xx switches

to Standard Speed.

OD_EN=0

Is Reset pulse

width for Standard

Speed?

TMP18xx Responds

in Overdrive Speed

Host Sends Address

Command

33h (READADDR)?

55h (MATCHADDR)?

F0h (SEARCHADDR)?

CCh (SKIPADDR)?

Yes

TMP18xx Sends 8 Bytes of

Address, LSb to MSb

Host Sends 8 Bytes of

Address, LSb to MSb

Does TMP18xx

Address Match?

Address Search Algorithm

Host Sends Func on

Yes

ECh (ALERTSEARCH)?

TMP18xx with

Alert Flag Set?

Yes

TMP18xx Sends FLAG

Yes

Host Sends FLAG

69h

(OVD_MATCHADDR)?

Host Sends 8 Bytes of

Address, LSb to MSb

Does TMP18xx

Address Match?

Yes

OD_EN=1

OD_EN=0

3Ch

(OVD_SKIPADDR)?

Yes

OD_EN=0

0Fh (FLEXADDR)?

Host Sends 1 Byte of

Short Address, LSb to MSb

Yes

Does TMP18xx Short

Address Match?

Yes

Is device in

Standard Speed?

Yes

Figure 8-20. Address Phase Flowchart

8.4.3.2.1 READADDR (33h)

The command can be used by the host to read the 64-bit address of the device. This command must only be

used when there is one device on the bus, as this command will cause a collision if multiple devices are present

on the bus.

8.4.3.2.2 MATCHADDR (55h)

The command is used by the host and is followed by a 64-bit address that is used to select a single device on

the bus. The address for each device is unique, therefore only one device can be selected by the command

while all other devices continue to wait for a bus reset.

8.4.3.2.3 SEARCHADDR (F0h)

The command is used by the host to identify the 64-bit address of each of the devices on the bus after the

system is powered up (see Figure 8-21). Additionally, this command may be run by the host to discover any

new devices that may be added to the system later. When there is a single device bus, the host can skip the

command and instead use the SKIPADDR command to access the device.

As shown in right side flow of Figure 8-21, when the fast arbitration mode is enabled by setting ARB_MODE

bits as '11b' in the device configuration-2 register, the devices check the bus for the transmitted bit. If the device

reads a bit value other than what they had transmitted, they no longer respond to the command until the next

bus reset. A device that wins the bus continues until the 64th bit, after which it does not respond to the next

SEARCHADDR command until the arbitration mode is reenabled. The arbitration function allows the host a fast

discovery of the devices without having to go through the complicated, memory intensive and longer discovery

method using traditional SEARCHADDR command. At the same time, if the host has an issue on the bus, then

it can simply perform a broadcast write to disable and enable the arbitration mode to restart the fast arbitration

mode.

The device also features an optimized arbitration mode which is enabled by setting ARB_MODE bits as '10b'.

The devices check the transmitted bit, and if the devices detect a logic '0' when they send a logic '1', they do

not participate in the SEARCHADDR command until the next SEARCHADDR command is sent. The device that

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TMP1827

SBOSA15 – SEPTEMBER 2022

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