User Manual

Data sheet
BMP085
Page 19
BST-BMP085-DS000-06 | Revision 1.3 | August 2011 Bosch Sensortec
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third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
4.5 Read A/D conversion result or E²PROM data
To read out the temperature data word UT (16 bit), the pressure data word UP (16 to 19 bit) and
the E
2
PROM data proceed as follows:
After the start condition the master sends the module address write command and register
address. The register address selects the read register:
E
2
PROM data registers 0xAA to 0xBF
Temperature or pressure value UT or UP 0xF6 (MSB), 0xF7 (LSB), optionally 0xF8 (XLSB)
Then the master sends a restart condition followed by the module address read that will be
acknowledged by the BMP085 (ACKS). The BMP085 sends first the 8 MSB, acknowledged by
the master (ACKM), then the 8 LSB. The master sends a "not acknowledge" (NACKM) and
finally a stop condition.
Optionally for ultra high resolution, the XLSB register with address 0xF8 can be read to extend
the 16 bit word to up to 19 bits; refer to the application programming interface (API) software
rev. 1.1 (“BMP085_SMD500_API”, available from Bosch Sensortec).
S
ACKS
Module address
write 0xEE
ACKS
Register address
e.g. 0xF6
MSB e.g.
ADC result 0x5C
ACKS
Module address
read 0xEF
Restar
t
ACKM
LSB e.g.
ADC result 0x96
NACKM
SCL
SDA
P
Figure 7: Timing diagram read 16 bit A/D conversion result