BMA020 datasheet(34/50 Pages) BOSCH

34 / 50 page

Data sheet

BMA020

Digital, triaxial acceleration sensor

Bosch Sensortec

Rev. 1.2

Page 34

30 May 2008

as copying and passing on to 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.

4.2.1 I²C protocol:

The BMA020 I²C slave address is coded on 7 bits (0111000b=38h) fixed by a metal option.

Thus I²C write address is 01110000b (=70h), read address is 01110001b (=71h).

After a start condition, the slave address + RW bit must be send. If the slave address does not

match with BMA020 there is no acknowledgement and the following data transfer will not affect

the chip. If the slave address corresponds to BMA020 it will acknowledge (pull SDA down

during 9th clock pulse) and data transfer is enabled. The 8th 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 and

one dummy bit.

When BMA020 is accessed in write mode, sequences of 2 bytes (= 1 control byte to define

which address will be written and 1 data byte) must be sent:

Figure 15: I²C multiple write protocol

Start

RW ACK

ACK

011

100

000

100

…

ACK

ACK Stop

…

000

111

Slave Adress

Control byte

Data byte

Control byte

Data byte

BMA020 Datasheet(PDF) 34 Page - Bosch Sensortec GmbH