Teledyne SENT Decoder User Manual

Instruction Manual

SENT Decoder

SENT Decoder Instruction Manual

Unauthorized duplication of Teledyne LeCroy documentation materials other than for internal sales and distribution purposes is strictly prohibited. However, clients are encouraged to distribute and duplicate Teledyne LeCroy documentation for their own internal educational purposes.

SENT and Teledyne LeCroy are registered trademarks of Teledyne LeCroy, Inc. Windows is a registered trademark of Microsoft Corporation. Other product or brand names are trademarks or requested trademarks of their respective holders. Information in this publication supersedes all earlier versions. Specifications are subject to change without notice.

922664 Rev A

March 2013

Instruction Manual

922664 Rev A

TABLE OF CONTENTS

Introduction .................................................................................................................. 2

About This Manual .................................................................................................................. 2

SENT Overview ........................................................................................................................ 2

Serial Decode Technical Overview .......................................................................................... 3

General Approach .................................................................................................................... 4

Setting Up the Decoder .................................................................................................. 5

Verify Bit-Level Decode ........................................................................................................... 7

Enable/Disable Decoder .......................................................................................................... 7

Working with the Decoded Waveform ............................................................................ 8

Serial Decode Annotations ...................................................................................................... 8

Search Waveform .................................................................................................................... 9

Working with the Result Table ..................................................................................... 10

Customize Decode Result Table ............................................................................................ 10

Export Decode Result Table .................................................................................................. 11

Teledyne LeCroy Service Centers .................................................................................. 12

SENT Decoder

922664 Rev A

Introduction

About This Manual

Teledyne LeCroy offers different toolsets for decoding and debugging serial data streams. These toolsets may be purchased as optional software packages, or are provided standard with SDA and DDA model oscilloscopes.

This manual explains how to use the SENTtoolset.

Assumptions

This manual is presented with the assumption that:

 You have a basic understanding of the various serial data standard physical and protocol layer

specifications, and know how these standards are used in embedded controllers.

 You have a basic understanding of how to use an oscilloscope, and specifically the Teledyne

LeCroy oscilloscope on which the serial trigger and decode option is installed. Only features directly related to serial data decode are explained in this manual; please see the oscilloscope online Help file, Operator's Manual, or Getting Started Manual for other instructions.

 You have purchased and installed one of optional serial data decoders described in this manual.

Compatibility

Teledyne LeCroy is constantly expanding coverage of serial data standards and updating software. Some capabilities covered in this documentation may only be available with the latest version of our firmware. You can download the firmware update from teledynelecroy.com.

While some of the screen images in this manual may not exactly match what is seen on your oscilloscope display—or show an example taken from your protocol—be assured that the functionality is nearly identical, as much functionality is shared.

SENT Overview

SAE J2716 SENT (Single Edge Nibble Transmission) protocol is a point-to-point scheme for transmitting signal values from a sensor to a controller. It is intended to allow for high-resolution data transmission with a lower system cost than available serial data solution. Data are transmitted in units of 4 bits = 1 nibble for which the interval between two falling edges (single edge) of the modulated signal with a constant amplitude voltage is evaluated. A data frame contains 24 bits of data (each 3 nibbles for 2 channels, such as pressure and temperature), 4 bits = 1 nibble for error detection (CRC) and 4 bits = 1 nibble of status and communication, making a total of 8 nibbles. Optionally, data can be transferred in a 5-nibble frame, with 3 nibbles for a single measurement channel, 1 for CRC and 1 for the status/communication. (SENT Protocol, wikipedia.org, accessed 03-06-2013).

Instruction Manual

922664 Rev A

The Teledyne LeCroy SENT decoder option is a tool aimed at decoding SENT streams emitted by various sensors. This decoder supports both the 2008 and the 2010 SENT specification through user-selectable variables.

Serial Decode Technical Overview

The algorithms described here at a high level are used by all Teledyne LeCroy serial decoders sold for oscilloscopes. They differ slightly for serial data signals that have a clock embedded in data or a clock separate from data.

The first software algorithm examines the embedded clock for each message based on a default (or user specified) vertical level. Once the clock signal is extracted or known, the algorithm examines the corresponding data signal at a predetermined vertical level to determine whether a data bit is high or low. The default vertical level is usually set to 50% and is determined from a measurement of peak amplitude of the signals acquired by the oscilloscope. It can also be set to an (absolute) voltage level, if desired. The algorithm intelligently applies a hysteresis to the rising and falling edge of the serial data signal to minimize the chance of perturbations or ringing on the edge affecting the data bit decoding.

NOTE: Although the decoding algorithm is based on a clock extraction software algorithm using a vertical level, the results returned are the same as those from a traditional protocol analyzer using sampling point-based decode.

After determining individual data bit values, another algorithm performs a decoding of the serial data message after separation of the underlying data bits into logical groups (Header/ID, Data Length Codes, Data, CRC, Start Bits, Stop Bits, etc.) specific to the protocol.

Finally, another algorithm applies a color overlay with annotations to the decoded waveform to mark the transitions in the signal. Decoded message data is displayed in tabular form below the grid. Various compaction schemes are utilized to show the data during a long acquisition (many hundreds or thousands of serial data messages) or a short acquisition (one serial data message acquisition). In the case of the longest acquisition, only the most important information is highlighted. In the case of the shortest acquisition, all information is displayed (Header/ID, Data Length Codes, Data, CRC, Start Bits, Stop Bits, etc.) with additional highlighting of the complete message frame.

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