AN3209 Datasheet, PDF (20/42 Pages) STMicroelectronics – Developing your M24LR64-R datalogger application for temperature acquisition

Component overview
AN3209
Read acquired temperature
To read the 2 bytes temperature register, the I²C master must send a Pointer Set
Configuration Register Write frame followed by a 2-byte read frame (see Figure 15).
This operation is managed by calling the I2C_SS_BufferRead(unit8_t* pBuffer,
unit16_t ReadAddr, unit8_t NumberByteToRead) function.
Figure 15. Typical pointer set followed by a READ for 2-byte register



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2.3.4
Temperature format
Table 8 shows the relationship between the output digital data and the external temperature
for 9 to 12-bit resolution. The left-most bit in the output data stream controls temperature
polarity information for each conversion. If the sign bit is '0', the temperature is positive and
of the sign bit is '1', the temperature is negative.
Table 8. Relationship between temperature and digital output
Temperature
(°C)
Sign
Number of bits used by
conversion resolution
9
10
11
12-bit resolution
11-bit resolution
10-bit resolution
0
9-bit resolution
0
0
+125
0
111
1101
0
0
0
+25.0625
0
001
1001
0
0
0
+10.125
0
000
1010
0
0
1
+0.5
0
000
0000
1
0
0
12
Always
zero
Digital
output
(Hex)
0000
0
0000
0
0000
0
0000
0
0000 7D00
1
0000 1910
0
0000 0A20
0
0000 0080
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Doc ID 17419 Rev 2