Datasheet

AT30TSE752A/754A/758A [DATASHEET]
Atmel-8854G-DTS-AT30TSE752A-754A-758A-Datasheet_102014
16
For Write operations to the AT30TSE752A/754A/758A, the Pointer Register value must be refreshed each time a Write
to the device is to be performed, even if the same data register is going to be written to a second time in a row.
Example: If the Pointer Register is set to point to the Configuration Register, once the subsequent Write operation to
the Configuration Register has completed, the user cannot write again into the Configuration Register
without first setting the Pointer Register value again. As long as a Write operation is to be performed, the
device will assume that the Pointer Register value is the first data byte received after the address byte.
Since only seven data registers are available for access, only the five LSBs (P4-P0) of the Pointer Register are used; the
remaining three bits (P7-P5) of the Pointer Register should always be set to zero to allow for future migration paths to
other temperature sensor devices that have more than seven data registers. In addition, the device incorporates
additional commands that are decoded in lieu of the Pointer Register byte; therefore, if bits P7-P5 are not set as zero
when setting the value of the Pointer Register byte, the device may interpret the data as one of the additional commands.
Table 6-2 shows the bit assignments of the Pointer Register and the associated pointer addresses of the data registers
available. Attempts to write any values other than those listed in Table 6-2 into the Pointer Register will be ignored by the
device, and the contents of the Pointer Register will not be changed. The device will respond back to the Master with a
NACK to indicate that the device received an invalid Pointer Register byte.
Table 6-2. Pointer Register and Address Assignments
To set the value of the Pointer Register, the Master must first initiate a Start condition followed by the
AT30TSE752A/754A/758A device address byte (1001AAA0 where “AAA” corresponds to the hard-wired A
2-0
address
pins). After the AT30TSE752A/754A/758A has received the proper address byte, the device will send an ACK to the
Master. The Master must then send the appropriate data byte to the AT30TSE752A/754A/758A to set the value of the
Pointer Register.
After device power-up or reset, the Pointer Register defaults to 00h which is the Temperature Register location;
therefore, the Temperature Register can be read from immediately after device power-up or reset without having to set
the Pointer Register. If the device is configured to power-up in the Shutdown mode, then the device will make a single
temperature measurement immediately after power-up so that valid temperature data can be output from the
Temperature Register.
Figure 6-1. Write Pointer Register
Pointer Register Value
Associated
Address
Register SelectedP7 P6 P5 P4 P3 P2 P1 P0
0 0 0 0 0 0 0 0 00h Temperature Register
0 0 0 0 0 0 0 1 01h Configuration Register
0 0 0 0 0 0 1 0 02h T
LOW
Limit Register
0 0 0 0 0 0 1 1 03h T
HIGH
Limit Register
0 0 0 1 0 0 0 1 11h Nonvolatile Configuration Register
0 0 0 1 0 0 1 0 12h Nonvolatile T
LOW
Limit Register
0 0 0 1 0 0 1 1 13h Nonvolatile T
HIGH
Limit Register
SCK
SDA
Address Byte Pointer Register Byte
Start
by
Master
ACK
from
Slave
MSB MSB
ACK
from
Slave
Stop
by
Master
1 0 0 1 A A A 0 0 P7 P6 P5 P4 P3 P2 P1 P0 0
1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9