TMP468 datasheet(17/49 Pages) TI2

17 / 49 page

TMP468

www.ti.com

SBOS762B – NOVEMBER 2016 – REVISED JUNE 2017

Product Folder Links: TMP468

Submit Documentation Feedback

Programming (continued)

7.5.1.3 Serial Bus Address

To communicate with the TMP468 device, the master must first address slave devices using a slave address

byte. The slave address byte consists of seven address bits and a direction bit indicating the intent of executing a

read or write operation. The TMP468 device allows up to four devices to be addressed on a single bus. The

assigned device address depends on the ADD pin connection as described in Table 2.

Table 2. TMP468 Slave Address Options

ADD PIN CONNECTION

SLAVE ADDRESS

BINARY

HEX

GND

1001000

V+

1001001

SDA

1001010

SCL

1001011

7.5.1.4 Read and Write Operations

Accessing a particular register on the TMP468 device is accomplished by writing the appropriate value to the

pointer register. The value for the pointer register is the first byte transferred after the slave address byte with the

R/W bit low. Every write operation to the TMP468 device requires a value for the pointer register (see Figure 16).

The TMP468 registers can be accessed with block or single register reads. Block reads are only supported for

pointer values 80h to 88h. Registers at 80h through 88h mirror the Remote and Local Temperature registers (00h

to 08h). Pointer values 00h to 08h are for single register reads.

7.5.1.4.1

Single Register Reads

When reading from the TMP468 device, the last value stored in the pointer register by a write operation is used

to determine which register is read by a read operation. To change which register is read for a read operation, a

new value must be written to the pointer register. This transaction is accomplished by issuing a slave address

byte with the R/W bit low, followed by the pointer register byte; no additional data are required. The master can

then generate a start condition and send the slave address byte with the R/W bit high to initiate the read

command; see Figure 17 through Figure 19 for details of this sequence.

If repeated reads from the same register are desired, continually sending the pointer register bytes is not

necessary because the TMP468 device retains the pointer register value until the value is changed by the next

write operation. The register bytes are sent by the MSB first, followed by the LSB. If only one byte is read (MSB),

a consecutive read of TMP468 device results in the MSB being transmitted first. The LSB can only be accessed

through two-byte reads.

The master terminates a read operation by issuing a not-acknowledge (NACK) command at the end of the last

byte to be read or transmitting a stop condition. For a single-byte operation, the master must leave the SDA line

high during the acknowledge time of the first byte that is read from the slave.

The TMP468 register structure has a word (two-byte) length, so every write transaction must have an even

number of bytes (MSB and LSB) following the pointer register value (see Figure 16). Data transfers occur during

the ACK at the end of the second byte or LSB. If the transaction does not finish, signaled by the ACK at the end

of the second byte, then the data is ignored and not loaded into the TMP468 register. Read transactions do not

have the same restrictions and may be terminated at the end of the last MSB.

7.5.1.4.2

Block Register Reads

The TMP468 supports block mode reads at address 80h through 88h for temperature results alone. Setting the

pointer register to 80h signals to the TMP468 device that a block of more than two bytes must be transmitted

before a stop is issued. In this mode, the TMP468 device auto increments the internal pointer. After the 18 bytes

of temperature data are transmitted, the internal pointer resets to 80h. If the transmission is terminated before

TMP468 Datasheet(PDF) 17 Page - Texas Instruments

TMP468 Datasheet(HTML) 17 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49

Datasheet Download

Link URL