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Preliminary Datasheet
SMB365
Three-axis accelerometer
Bosch Sensortec
3.2
SPI Protocol
The used protocol corresponds to the standard SPI mode 3.
SPI Memory Write cycle description
CSB
SCK
MOSI
MISO
R/W
A5
A4A3A2
A1
A0
XX
XXXXX
A6 .. A0 :
7 Address bits
D7 .. D0 :
8 Data bits
SPI Memory Read cycle description (divided in two SPI cycles due to EEPROM read access time)
CSB
SCK
MOSI
MISO
R/W
A5A4A3A2A1
A0
HiZ
A6 .. A0 :
7 Address bits
D7 .. D0 :
8 Data bits
D7
D6
D5
D4
D3
D2
X
SCK frequency : 8 MHz max.
X
SPI Acceleration/Temperature Read cycle description
CSB
SCK
MOSI
MISO
HiZ
D1
D0
A6
A6
HiZ
R/W
A5A4
A3A2
A1
A0
A6
D7
D6
D5
D7
D6
D5
D4
D3
D2
D1
R/W
A5A4A3A2A1
A0
HiZ
A6 .. A0 :
7 Address bits
D7 .. D0 :
8 Data bits
X
D0
A6
EM/WIL 08/10/03
HiZ
X
D4
D3
D2
D1
D0
HiZ
Due to the standard 16-bit protocol, the digital codes for the acceleration values must be read by two
successive SPI cycles. The user has to read the 7 MSB first and then the 3 LSB. It is also possible to
read only the 7 MSB.
The 3 LSB are protected in such a way that during the read-out of the 7 MSB the LSB are not changed or
updated. The update of the LSB does not take place before the MSB are read again. Therefore it cannot
happen that a mixed acceleration value is read.
Rev. 1.2
Page 6
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