Host

Device

(1)

Device

(2)

Device

(N)

RX

TX

Interface Logic

Interface Logic

Interface Logic

RX

RX

RX

TX

TX

TX

Host

Device

(1)

Device

(2)

Device

(N)

RX

TX

Interface Logic

Interface Logic

Interface Logic

RX

RX

RX

TX

TX

TX

Host

Device

(1)

Device

(2)

Device

(N)

RX

TX

Interface Logic

Interface Logic

Interface Logic

RX

RX

RX

TX

TX

TX

TMP104

SBOS564A

– NOVEMBER 2011 – REVISED NOVEMBER 2011

www.ti.com

GLOBAL INITIALIZATION AND ADDRESS ASSIGNMENT SEQUENCE

At device power-up, every TMP104 in the daisy-chain is connected in transparent mode, as shown in Figure 7.

The host must send the initialization command (P7-P0 = 10001100) in order for the bus to program its internal

address depending on the number of devices on the bus.

Figure 7. TMP104 Daisy-Chain: Bus Status at Start of Global Initialization

Each TMP104 in the chain interprets the initialization command byte and disconnects the chain, as shown in

Figure 8. The host must then send the address assignment command, consisting of P7-P4 = 1001 and P3-P0 =

0000, where P3-P0 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 9. This address is then sent to the next device in the chain. Once all devices on the chain have received

the respective addresses, the host receives the last programmed address on the chain + 1. The host can use

this information to determine the total number of devices in the chain and the respective address of each device.

After the initialization sequence, every device can be addressed individually or through global commands. This

global initialization sequence is a requirement and must be performed before any other communication.

Figure 8. TMP104 Daisy-Chain: Bus Status at Start of Address Assignment

Figure 9. TMP104 Daisy-Chain: Bus Status After First Device Address Assignment

8

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© 2011, Texas Instruments Incorporated

Product Folder Link(s): TMP104