LSM303DLMTR datasheet(19/38 Pages) STMICROELECTRONICS

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LSM303DLM

Digital interfaces

Doc ID 018725 Rev 1

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7.1.2

Linear acceleration digital interface

For linear acceleration, the default (factory) 7-bit slave address is 001100xb. The SDO/SA0

pad can be used to modify the least significant bit of the device address. If the SA0 pad is

connected to voltage supply, the LSB is ‘1’ (address 0011001b) otherwise, if the SA0 pad is

connected to ground, the LSB value is ‘0’ (address 0011000b). This solution permits

connecting and addressing two different accelerometers to the same I2C lines.

The slave address is completed with a read/write bit. If the bit is ‘1’ (read), a repeated

START (SR) condition must be issued after the two sub-address bytes; if the bit is ‘0’ (write),

the master transmits to the slave with the direction unchanged.

Table 12 explains how the

SAD+read/write bit pattern is composed, listing all the possible configurations.

In order to read multiple bytes, it is necessary to assert the most significant bit of the sub-

address field. In other words, SUB(7) must be equal to 1 while SUB(6-0) represents the

address of the first register to be read.

In the presented communication format, MAK is master acknowledge and NMAK is no

master acknowledge.

7.1.3

Magnetic field digital interface

For magnetic sensors the default (factory) 7-bit slave address is 0011110xb.

The slave address is completed with a read/write bit. If the bit is ‘1’ (read), a repeated

START (SR) condition must be issued after the two sub-address bytes; if the bit is ‘0’ (write),

the master transmits to the slave with the direction unchanged.

Table 14 explains how the

SAD is composed.

Table 12.

SAD and read/write patterns

Command

SAD[6:1]

SAD[0] = SA0

R/W

SAD+R/W

Read

001100

00110001 (31h)

Write

001100

00110000 (30h)

Read

001100

00110011 (33h)

Write

001100

00110010 (32h)

Table 13.

Transfer when master is receiving (reading) multiple bytes of data from slave

Master

ST SAD+W

SUB

SR SAD+R

MAK

NMAK SP

Slave

SAK

SAK DATA

DATA

Table 14.

SAD and read/write patterns

Command

SAD[6:0]

R/W

SAD+R/W

Read

0011110

00111101 (3Dh)

Write

0011110

00111100 (3Ch)

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