As shown in Figure 7-8, the host must send the initialization command (C[7:0] = 10001100) for the bus to

program its internal address, depending on the number of devices on the bus.

GLBL

IN3/ID3

IN2/ID2

IN1/ID1

IN0/ID0

P1

P0

R/W

1

0

0

0

1

0

0

1

S

P

0

1

0

1

0

1

0

1

S

P

Calibration Byte (55h)

Command Byte

Address Assignment Command (90h)

0

1

0

0

1

1

0

0

S

P

Device 1 (TX) Device 2 (RX)

Host TX

Device-1

TX

Device-2

TX

Host TX

Device-1

TX

Device-2

TX

0

1

0

0

1

0

0

0

S

P

0

1

0

0

1

0

1

0

S

P

Device 2 (TX) Device 3 (RX)

Host TX

Device-1

TX

Device-2

TX

1

0

0

0

1

0

0

1

S

P

0

1

0

1

0

1

0

1

S

P

1

0

0

0

1

0

0

1

S

P

0

1

0

1

0

1

0

1

S

P

Devices

in Pass

Through

Figure 7-8. Global Initialization and Address Assignment Command Flow

Each TMP144 in the chain interprets the initialization command byte and disconnects the chain, as shown in

Figure 7-9.

Host

Device

(1)

Device

(2)

Device

(N)

RX

TX

Interface Logic

Interface Logic

Interface Logic

RX

RX

RX

TX

TX

TX

Figure 7-9. TMP144 Daisy-Chain: Bus Status at Start of Address Assignment

The host must then send the address assignment command, consisting of C[7:4] = 1001 and C[3:0] = 0000,

where C[3:0] represents the address of the first device in the chain. This word is stored internally as its device

ID. The first device increments the unit in the device address and then reconnects the bus, as shown in Figure

7-10. This address is then sent to the next device in the chain.

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TMP144

SBOS891A – OCTOBER 2018 – REVISED FEBRUARY 2021

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