Specifications

BMA180
Preliminary data sheet
Bosch Sensortec
Rev. 1.0 Page 61 / - proprietary information - 06 March 2009
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Specifications within this document are preliminary and subject to change without notice. Document is not intended for publication.
8.3.4 Acknowledge
After a start condition, data bits are transferred to BMA180. Each byte is followed by an
acknowledge bit: the transmitter let the SDI line high (no pull down) and generates a high SCK
pulse; if transfer concerns the BMA180 slave receiver and has performed correctly, it generates
a low SDI level (pull down activated). After acknowledge, BMA180 let SDI line free, enabling the
transmitter to continue transfer or to generate a stop condition.
SDI
By transmitter
SCK
Start condition
S
SDI
By receiver
9 8 2 1
Acknowledge
Not Acknowledge
Clock pulse for
acknowledgement
Figure 14: acknowledgement on SDI line
8.3.5 I
2
C protocol
After a start condition, the slave address + RW bit must be send. If the slave address does not
match with BMA180 one, there is no acknowledgement and the following data transfer will not
affect the chip. If the slave address corresponds to BMA180 one, it will acknowledge (pull SDI
down during 9
th
clock pulse) and data transfer is enabled. The 8
th
bit RW sets the chip in read or
write mode, RW=1 for reading, RW=0 for writing.
After slave address and RW bit, the master sends 1 control byte:
- the 7-bit register address
- 1 dummy bit
When IC is accessed in write mode, sequences of 2 bytes (= 1 control byte to define which
address will be written and 1 data byte to fill it) must be sent:
The following transactions are supported:
Single byte read, Single byte write, Multiple byte read, Multiple byte write.
Transactions are described in the following figures.