BMA255 datasheet(98/119 Pages) BOSCH

98 / 119 page

BMA255

Data sheet

Page 98

BST-BMA255-DS004-05 | Revision 1.2 | August 2014

Bosch Sensortec

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.

The following figure shows the definition of the SPI timings given in the following figure:

tSDI_hold

tSCKH

tCSB_hold

tCSB_setup

tSDI_setup

tSCKL

tSDO_OD

CSB

SCK

SDI

SDO

Figure 13: SPI timing diagram

The SPI interface of the BMA255 is compatible with two modes, ´00´ and ´11´. The automatic

selection between [CPOL = ´0´ and CPHA = ´0´] and [CPOL = ´1´ and CPHA = ´1´] is controlled

based on the value of SCK after a falling edge of CSB.

Two configurations of the SPI interface are supported by the BMA255: 4-wire and 3-wire. The

same protocol is used by both configurations. The device operates in 4-wire configuration by

default. It can be switched to 3-wire configuration by writing ´1´ to (0x34) spi3. Pin SDI is used

as the common data pin in 3-wire configuration.

For single byte read as well as write operations, 16-bit protocols are used. The BMA255 also

supports multiple-byte read operations.

In SPI 4-wire configuration CSB (chip select low active), SCK (serial clock), SDI (serial data

input), and SDO (serial data output) pins are used. The communication starts when the CSB is

pulled low by the SPI master and stops when CSB is pulled high. SCK is also controlled by SPI

master. SDI and SDO are driven at the falling edge of SCK and should be captured at the rising

edge of SCK.

BMA255 Datasheet(PDF) 98 Page - Bosch Sensortec GmbH