L9300 datasheet(31/178 Pages) STMICROELECTRONICS

31 / 178 page

Figure 15. WSI control blocks

GADG1107170932PS

Remote sensor configuration can be addressed via the Remote Sensor Configuration Registers (WSIRSCRx).

The Remote Sensor Control Register (WSICTRL) allows for digital algorithm and DOUTx output buffer of each

channel to be switched on and off; sensor supply interface is indeed automatically enabled during the power-up

sequence of the device.

Each TRKn interface is kept independent from each other with dedicated logic and protected against faults on

TRKn pins (short to battery or to ground).

In the VDA sensor communication, data bit D0 in the WSIRSDRx register might be used by the sensor as a fault

bit. Therefore, this bit is latched as D0_L in order to detect whether a fault has occurred: the data bits are instead

updated every speed pulse so intermittent fault conditions could be lost. This bit is cleared-upon-read.

If the device detects an error on the sensor interface, the FLTBIT in WSIRSDRx will be set to ‘1’ and the following

bits will be used to report the detected errors. Otherwise, the register will contain only data information. Detailed

information on data and fault reporting are explained in the following sections.

Active wheel speed sensor

The remote sensor interface senses circuit conditions and decodes active wheel speed sensor signals with

various pulse widths and output currents. The following sensor types are supported and selected through the

Remote Sensor Configuration Register (WSIRSCR).

•

Standard active 2-level wheel speed sensors (7/14mA similar to ATS682LSHTN)

•

Three-level (7/14/28 mA similar to KMI22) VDA compliant sensor with direction and air gap information

(“Requirement Specification for Standardized Interface for Wheel Speed Sensor with Additional

Information”, Version 2.0)

•

PWM encoded 2-level sensors with 2 edges per tooth (similar to TLE4942/BOSCH DF11)

•

PWM encoded 2-level sensors with 1 edge per tooth (similar to ATS651LSH/BOSCH DF11)

Received wheel speed frames from all the above sensors are decoded into signals suitable for the microcontroller

through the four independent DOUTx output pins.

L9300

Power supply

DS12258 - Rev 5

page 31/178

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