Host

Device

(1)

Device

(2)

Device

(N)

RX

TX

Interface Logic

Interface Logic

Interface Logic

RX

RX

RX

TX

TX

TX

10

TMP104

SBOS564B – NOVEMBER 2011 – REVISED DECEMBER 2018

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7.3.5 Global Clear Interrupt

The host can initiate a global clear interrupt command (P7-P0 = 10101001) to all TMP104s in the daisy-chain.

Upon receiving this command, the TMP104 disables future interrupts (D7 in the Configuration Register is set to

'0'). If a TMP104 has previously broken the bus connection and sent an interrupt (logic low on the bus), it now

stops holding the bus low. The device sends the baud rate calibration command and clear interrupt command to

the next TMP104 in the chain, and then reconnects the bus. In the case of multiple devices having active

interrupts, the clear interrupt command propagates through the daisy-chain, disables all interrupts, and

reconnects the bus across all devices.

7.3.6 Global Software Reset

The host can initiate a global software reset command (P7-P0 = 10110100) to all TMP104s in the daisy-chain.

Upon receiving this command, the TMP104 resets its internal registers except for the device ID, which is not

reset, and reconnects the bus. If the bus is broken before the initiation of this command, all TMP104s before the

broken bus point receive the command. If the host intends to initiate a global software reset across all TMP104s

in the chain, this command must be transmitted multiple times until it echoes back to the host.

7.3.7 Individual Read and Write

The host can initiate an individual read/write command to a particular TMP104 in the daisy-chain by sending the

read/write command. The read/write command consists of these parameters:

•

P7 = 0

•

P6-P3 = the device ID

•

P2-P1 = the data register pointer; see Table 4

•

P0 = indicates read/write control

P0 = 0 indicates an individual write command; the host must transfer one more byte of data for the register

indicated by bits P2-P1. The TMP104 in the daisy-chain that corresponds to the device ID noted by bits P6-P3

then updates the appropriate register. P0 = 1 indicates an individual read command; as shown in Figure 12, the

TMP104 in the daisy-chain that corresponds to the device ID pointed by bits P6-P3 then breaks the bus,

transmits the data from the register pointed by bits P2-P1, and reconnects the bus.

Figure 12. TMP104 Daisy-Chain: Bus Status During Individual Read Operation of Second Device

7.4 Register Maps

7.4.1 Temperature Register

The Temperature Register of the TMP104 is configured as an 8-bit, read-only register that stores the output of

the most recent conversion. A single byte must be read to obtain data, and is described in Table 5. The data

format for temperature is summarized in Table 6. One LSB equals 1°C.