TLE4998S8D Grade1

SENT Output Definition (SAE J2716)

Technical Product Description

19

Revision 1.0, 2013-02-22

9

SENT Output Definition (SAE J2716)

The sensor supports a basic version of the Single Edge Nibble Transmission (SENT) protocol defined by SAE.

The main difference between the standard version and its implementation in the TLE4998 is the usage of an open

drain instead of a push-pull output.

9.1

Basic SENT Protocol Definition

•

The single edge is defined by a 9-μs low pulse on the output, followed by the high time defined in the protocol

(nominal values, may vary by tolerance of internal RC oscillator and the programming, see Chapter 9.2). All

values are multiples of a 3-μs unit time frame concept. A transfer consists of the following parts:A

synchronization period of 168 μs (in parallel, a new sample is calculated)

•

A synchronization period of 56 UT (in parallel, a new sample is calculated)

•

A status nibble of 38-81

μs

•

Three data nibbles of 36-81

μs (data packet 1 with a length of 103-243 μs)

•

Three data nibbles of 36-81

μs (data packet 2 with a length of 103-243 μs)

•

A CRC nibble of 38-81

μs

Figure 9-1

SENT Frame

The CRC checksum calculation includes the status nibble and the data nibbles. This leads to a minimum transfer

time of 456 μs, and a maximum transfer time of 816 μs per sample.

It is important to know that the sampling time (when values are taken for temperature compensation) here is

always defined as the beginning of the synchronization period; during this period, the resulting data is always

calculated from scratch.

As only one Hall value needs to be transferred within one sequence, the second data package is divided into two

parts (see Figure 9-2).

•

First, the remaining 4 LSBs of the Hall signals are transferred in the first data nibble. This means the receiver

may use the whole 16-bit data available in the sensor when reading and using all 4 nibbles transferred.

•

Second, the temperature is transferred as an 8-bit value. The value is transferred in unsigned integer format

and corresponds to -55°C to 200°C. For example, transferring the value 55 corresponds to 0°C. The

temperature is additional information and although it is not calibrated, may be used for a plausibility check, for

example.

compensate the

sample

transfer compensated sample

Sensor processing

Output pin (physical)

Transferred data (logical)

sync. period

Status

nibble

Data

nibble 1

high

Data

nibble 2

low

CRC

nibble

check

lowtime,

process

sensor

idle

sensor

idle

zero

nibble

falling edge/ low time of

master requires sensor

response