TMP139AIYAHT datasheet(15/58 Pages) TI

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S or Sr

HID2

HID1

HID0

R/W=0

RA = Register Address [7:0]

ACK/NACK

Data(RA)

Data(RA+1)

ACK/NACK

ACK

...

ACK

HID2

HID1

HID0

R/W=1

Data(RA+N)

Sr or P

NACK

Figure 7-7. I2C Read Operation

7.4.3.3 Host I2C Read Operation in Default Read Address Pointer Mode

The TMP139 provides a default read address pointer mode as shown in Figure 7-8 to read a specific register on

the I2C bus. Since the number of bytes to be sent by the host are two less than a standard I2C read operation,

this mode provides for a more efficient polling mechanism. The MR18 register, bit DEF_RD_ADDR_POINT_EN

is used to enable the mode and bits DEF_RD_ADDR_POINT_Start are used to set the default read address

pointer to a specific register in the register map. When enabled, the TMP139 shall set the internal read address

pointer to the specific register when there is a Stop condition on the bus.

Data(DEF_ADDR_POINTER)

Data(DEF_ADDR_POINTER+1)

ACK/NACK

ACK

...

ACK

S or Sr

HID2

HID1

HID0

R/W=1

Data(DEF_ADDR_POINTER+N)

Sr or P

NACK

Figure 7-8. I2C Default Read Address Pointer Mode

There can be two specific cases in this mode of operation. In the first case as shown in Figure 7-9, there is a

normal I2C read preceding the default read mode. If a Stop precedes the Start, then the internal read address

pointer shall be set to the default address pointer and subsequent data reads shall result in the data bytes sent

by the TMP139 corresponding to the default read address pointer. If a Repeated Start is issued instead of a

Stop, then the TMP139 shall send data based on the default read address pointer.

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TMP139

SNIS217 – DECEMBER 2020

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