CAN LIN Flexray Automotive Seminar

Automotive Low Speed Serial Bus Analysis with Tektronix Oscilloscopes

Automotive Serial Bus Overview  I2C  SPI  CAN  FlexRay  USB (Infotainment: UserDevice Access)

 MOST 50 / 150 (Infotainment: Network)  Ethernet (BroadR-Reach® PHY , Broadcom)  MIPI (D-Phy, DSI / CSI)  HDMI / MHL

2

SPI

Trace Data Flow Through an Automotive Network  Trace serial data flow between nodes through a network – Simultaneously display messages at transmitter and receiver to verify continuity and propagation delays

 Trace serial data flow between network segments separated by a gateway – Simultaneously display messages from multiple buses, at different speeds, or even different bus standards LIN

Diagnostic

Engine Control Right Door

ESP

Gear Box

Left Door

CAN Gateway

CAN

Seat Control

Climate Control

CAN

Mobile Phone

Air Bag

ABS

Car Radio

Sensor

ABS Multi Media Module

Motor

LIN

3

CAN

Automotive Bus Technology - Application Areas 

Data Backbone for ADAS (Active Driver Assistance Systems)



Data Interchange with other specific automotive bus systems (CAN/Flexray)

Source: www.mostcooperation.com

4

Midrange Scope Portfolio

MSO/DPO2000

MSO/DPO3000

MSO/DPO4000B

MSO/DPO5000

DPO7000C

1 GHz – 350 MHz

2 GHz – 350 MHz

3.5 GHz – 500 MHz

1 GS/s

500 - 100 MHz 2.5 GS/s

5 – 2.5 GS/s

10 - 5 GS/s

40 - 5 GS/s

1M Samples Max

5 M Samples Max

20 M Samples Max

250 M Samples Max

500 M Samples Max

200 - 100 MHz

Embd. OS

Tektronix Confidential

MS WIN 7

Debugging Serial Buses with the MSO/DPO Series Automated Trigger, Decode and Search for Serial Buses

4000B Series

3000 Series

2000 Series

Bandwidth

1 GHz, 500 MHz, 350 MHz

500 MHz, 300 MHz, 100 MHz

200 MHz, 100 MHz

Channels

4 analog 16 digital (MSO Series)

2 or 4 analog 16 digital (MSO Series)

2 or 4 analog 16 digital (MSO Series)

Record Length

20 M points

5 M points

1 M points

Serial Bus Analysis

      

   

 I2C, SPI  CAN, LIN  RS-232/422/485/UART

# of Simultaneous Decoded Buses

4

I2C, SPI USB Ethernet CAN, LIN, FlexRay RS-232/422/485/UART I2S/LJ/RJ/TDM MIL-STD-1553

2

I2C, SPI CAN, LIN RS-232/422/485/UART I2S/LJ/RJ/TDM

2

Speed debug of serial buses with the MSO/DPO5000 Series

MSO/DPO5000 Series  350 MHz to 2 GHz  Up to 250 M record length  Comprehensive verification including compliance with jitter and eye validation  Physical layer testing for USB 2.0 and Ethernet 10/100/1000BASE-T  Serial bus decode, trigger and search support for: – I2C – SPI – UART/RS-232 – USB 2.0 – MOST 50 / 150

Automated Decode, Trigger, Search and Eye Diagram Analysis 7

In-Depth Analysis of Serial Buses with the DPO7000 Series Automated Decode, Trigger, Search and Eye Diagram Analysis

DPO7000 Series  500 MHz to 3.5 GHz  Up to 500 M record length  Physical layer testing for USB 2.0, Ethernet and MIPI  Serial data characterization with jitter and eye analysis  Supported serial buses: – I2C – SPI – CAN – LIN – FlexRay – UART/RS-232 – MOST 50 / 150

V6.4.0 Firmware for 5k, 7kC, 70kC/D WIN7 Scopes  Great new features – – – – – –

New bus standards support Improvements to Visual Trigger New “mark all trigger events” Search capability Improved Zoom and Cursor button operation Measurements on digital channels MATLAB and MS Visual Studio math plug-in functionality

 Performance improvements – Faster MSO/DPO5k operation – FastFrame and long record length speed increased

 Defect fixes for many customer-reported bugs  Larger HDD and SSD  New PS2 power bundle 

Available end of June 2012 – Available for all demo units now - update yours today! – New one-step complete update with “deployment package”

New Standards Support  CAN/LIN/FlexRay (trigger/decode/search)  MIL-STD-1553B (trigger/decode/search)  PCI Express gen 1/2/3 (trigger (70k)/decode/search)

 SPI 2-wire (trigger/decode/search)  8b/10b added to MSO/DPO5k and DPO7kC (decode/search)  MIPI D-PHY added to MSO/DPO5k (decode/search)

 Electrical Compliance Measurements – MOST 50 and 150 electrical compliance – Thunderbolt

LSS Trigger/Decode/Search  CAN/LIN/FlexRay: SR-AUTO  MIL-STD-1553: SR-AERO  2-Wire SPI added to SR-EMBD

CAN Bus: SR-AUTO

MIL-STD-1553: SR-AERO 2-Wire SPI: SR-EMBD

How do I probe serial digital buses?  Digital buses are not digital  Digital signals do not necessarily have only two discrete levels

 Digital probes are not digital  Everything you know about analog probing still applies – Minimize DC and AC loading

– Voltage measurements are always differential – Minimize lead inductance

Bus and Waveforms display of I2C signal

 The real signal must be delivered to the oscilloscope’s hardware or software comparator, where it can be compared to the digital threshold value(s) 12

What do the probing and acquisition architectures look like

P6616 passive probe

Digital input circuit (logic analyzer ASIC) front-panel connector

0.2pF 3pF

13

coax 100k

acquisition circuit

+

Acquisition System

Digital Acquisition System

MSO/DPO4000B / 5000 Series and P6616 Digital Probe Specification Maximum Sample Rate Maximum Input Toggle Rate DC Input Voltage Range Maximum Input Voltage Swing Input Impedance Input Capacitance Threshold Range Minimum Input Swing Minimum Detectable Pulse

MSO4000

MSO4000B

MSO5000

500MS/s 16.5GS/s with MagniVu

500MS/s 16.5GS/s with MagniVu

500MS/s 16.5GS/s with MagniVu

350 MHz

500 MHz

500 MHz

± 15 V

± 42 Vpeak

± 42 Vpeak

6 Vp-p centered on threshold

30 Vp-p ≤200MHz 10 Vp-p >200 MHz

30 Vp-p ≤200MHz 10 Vp-p >200 MHz

20 kOhm

100 kOhm

100 kOhm

3 pF

3 pF

3 pF

-2 V to +5 V

± 40 V

± 40 V

500 mVp-p

400 mVp-p

400 mVp-p

1.5 ns

1 ns

1 ns

P6616 16-channel digital probe matched to the digital acquisition system

high end digital specification 14

I2C (Inter-Integrated Circuit)  Used for chip-to-chip communication between microcontrollers and A/Ds, D/As, FPGAs, sensors, etc.  Uses two single-ended, bi-directional signals: clock and data (Half Duplex)  Any I2C device can be attached to the bus  Data rates: – Standard Mode (100 kbps) – Fast Mode (400 kbps) – High Speed Mode (3.4 Mbps)

15

I2C (Physical Part) +V Pull-up resistors

SDA SCL Master

16

Device 3

Device 4

Input Source Selection (example: I2C)  CH1 – CH4

 D0 – D15 (MSO)  View different busses simultaneously  Channel Labeling

17

I2C Message Structure

 Start: Indicates the device is taking control of the bus and a message will follow

 Address: 7-bit or 10-bit number representing the device address to read or write  Data: Integer number of bytes read from or written to the device  Acknowledge: 1-bit from the slave device acknowledging the master’s actions  Stop: Indicating the message is complete and the master has released the bus

18

Serial Debug

Manually Decoding Serial Bits  Engineers must manually count each bit and determine if it is a 1 or a 0

1010000 1

19

00010100

00100110

Serial Debug

Manually Decoding Serial Bits  Engineers must then convert the data to an understandable format

First three bits are most significant digit of a 7-bit address Next four bits are least significant digit of a 7-bit address Read or Write Most significant digit of 8-bit byte Least significant digit of 8-bit byte

1010000 1

00010100

00010110

= Read data 14 and 16 from Address 50 1 4 1 6 5 0 R

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Serial Debug

Serial Triggering and Decode  I2C Decoding is done by oscilloscope for the engineer

There must be a better way…

21

I2C Message Flow Control  Acknowledge/No Acknowledge – Indicates success or failure of a data transmission or the continuation of a transfer – Generated by holding the SDA low on the 9th clock pulse

SDA

ACK SCL

1

2

3

...

8

9

1

2

3

...

8

9

SDA

NACK SCL

22

I2C Solution on Tektronix Oscilloscope

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SPI (System Peripheral Interface)  Used primarily to communicate between microcontrollers and their immediate peripheral devices  Typical configuration has four signals: SCLK, MOSI, MISO, SS – Data is simultaneously transmitted and received – SS line used to specify slave device – Each unique device on bus has its own SS signal from master

 Multiple bus configurations are allowed – Network can use 2-, 3-, or 4-wire bus topology

 Data rates up to 50 Mbps SS – enables slave device to accept data

SS

MOSI – data from the master to a slave

MOSI (n bits) MSB

MISO – data from a slave to the master SCLK – serial clock driven by Master

24

LSB MISO (n bits)

MSB

LSB SCLK

SPI (System Peripheral Interface) Single Master Multiple Slaves

Single Master hardwired to Single Slave

SPI Bus Hardware Configurations

25

Serial Debug

Serial Triggering and Decode 

There is more than just decoding – – – –

Trigger on packet content Search and mark packet content View data in an Event Table format View two buses simultaneously

SPI

I2 C RS-232

FlexRay 26

CAN

LIN

CAN (Controller Area Network)  Used for system-to-system communication in Automotive, Industrial Automation, and Medical Equipment  Serial asynchronous, multi-master, layered communication network – Sophisticated error detection and error handling mechanisms – Flexible signaling support for low-cost implementation – Messages are broadcast to all nodes on the network

 Physical bus is single-wire or dual-wire, and fault tolerant  Data rates from 5 kbps to 1 Mbps CAN Bus Bit Rate Table

CAN High Speed Differential Bus Signal

dominant

Tx CAN Controller

Rx CAN_H

Rx

CAN_L

Tx

Electronic Control Unit

CAN-H

3.5V 2.5V

1

0

1

1.5V

CAN Physical Layer

CAN-L recessive

27

Min. CAN Pulse Width

CAN Bit Rate

recessive

1 Mbps

1 s

800 Kbps

1.25 s

500 Kbps

2 s

250 Kbps

4 s

125 Kbps

8 s

83.3 Kbps

12 s

62.5 Kbps

16 s

50 Kbps

20 s

33.3 Kbps

30 s

20 Kbps

50 s

10 Kbps

100 s

CAN is a differential BUS CAN High Speed Differential Bus Signal

Tx CAN Controller

Rx CAN_H

Rx

CAN_L

CAN Physical Layer

Tx

dominant Electronic Control Unit

CAN-H

3.5V 1

2.5V

0

1

1.5V CAN-L recessive

Tx

+ +

- -

path

+

+

-

-

Rcv

recessive

In-Depth Analysis of Network Performance 40 meters Node 10

120Ὠ

CAN Network

Node 2

120Ὠ

Node 1

Near End

Far End

 Locate and analyze signal integrity problems with eye diagrams

 Characterize different oscillator tolerances and propagation delays between nodes for synchronizing the network  Monitor bus utilization to ensure efficient use of the network 29

Eye diagram measurements Fast Data Rates, More HF Loss Clean, open, logical 1 & 0 at launch from transmitter

Tx

+ +

Logical 1 & 0 can be hard to distinguish at end of long interconnects; (this is often called a “closed eye”)

+ +

path

- -

-

Rcv

-

Fast, sharp, edges at transmitter launch Smeared edges at end of long interconnect.

Reference Maxim Note HFDN-27.0 (Rev. 0, 09/03)

CAN Data and Remote Frame Overview

 SOF: begins with a start of frame (SOF) bit  Arbitration: Identifier (address) and Remote Transmission Request (RTR) bit  Control: 6 bits including Identifier Extension (IDE) bit and Data Length Code (DLC)  Data: zero to eight bytes of data  CRC: 15-bit cyclic redundancy check code and a recessive delimiter bit

 ACK: acknowledge field is two bits long  EOF: 7 recessive bits indicate the end of frame (EOF)  INT: intermission field of three recessive bits indicates the bus is free 31

Characterize System Timing  Characterize timing between bus messages and system operation – Requires waveform displays time-correlated with decoded messages

 Characterize timing differences which occur when adding a new network node to an existing network  Automotive application example: – Measure worst-case time from crash sensor output to airbag activation – Measure variations in timing of airbag activation with varying levels of CAN bus traffic

32

CAN Bus

33

DPO7000 CAN Trigger

CAN Bus

DPO7000 CAN Analysis Application Select Function : • Decoding • Timing Analysis

34

CAN Bus

DPO7000 CAN Analysis Application Configure : • Trig.-Source • Bus-Source

35

CAN Bus

DPO7000 CAN Analysis Application Trig.-Configure : • Field Type • Field Value

36

CAN Bus

DPO7000 CAN Analysis Application Decoding Results : • Field Value • Timing Result

37

CAN Bus

DPO7000 CAN Analysis Application Decoding Results : • Correlation to Acq.-Mem

38

Characterizing Oscillator Tolerance and Propagation Delay  Oscillator tolerance of a CAN node – Specify the specific ID for trigger condition – Result will include ACK and without ACK bit – With ACK bit, shows the impact of receiving CAN node oscillator tolerance on transmitting node

 Propagation Delay – Connect two channels to any two CAN nodes – Result is directly available

39

Monitoring CAN Traffic for Bus Utilization  Measure at specific ID, error frame or overload frame  Specifies percentage of time traffic present in the CAN bus  Type of traffic can be analyzed – Frame count

Tektronix DPO7000 Series with TDSVNM option 40

CAN Trigger Overview

41

FlexRay 2.1 (3.0)  FlexRay is a automotive bus still being developed by a group of leading automotive companies and suppliers known as the FlexRay Consortium  The physical bus can be unshielded twisted pair, or shielded twisted pair to improve EMC performance  FlexRay is a differential serial bus configured in three recurring segments: Header, Payload, and Trailer  Each frame contains a static and dynamic segment, and bus idle time concludes each frame  Transmitted data rates up to 10 Mbps Automotive  Manufacturers are finding that existing automotive serial standards

such as CAN and LIN do not have the speed, reliability, or redundancy required to address X-by-wire applications such as brake-by-wire or steer-by-wire. 42

FlexRay Frame Structure



Header Segment –



Payload Segment –



Contains data transferred by the frame. Maximum payload length is 127 words (254 bytes)

Trailer Segment –

43

Contains Indicator Bits, Frame ID, Payload Length (in words), Header CRC, and Cycle Count

Contains a single 24 bit field [three 8 bit CRC registers] for header and payload protection

FlexRay Terms and Abbreviations FlexRay Bus Decode Terms TSS (Transmission Start Sequence): initiate network connection setup. FSS (Frame Start Sequence): immediately follows TSS Indicator Bits: provides Header Segment preamble information. Frame Id (Frame Identifier): defines to which slot frame is transmitted. Payload Length: indicates data size being transferred in the frame. Header CRC: contains CRC computed from portion of Header Segment. Cycle Count: holds value that increments for each comm. cycle start. Data (Payload): contains data transferred by frame (254 bytes max.). Trailer CRC: protects against improper header and payload modification. FES (End of Frame): immediately follows the Trailer CRC DTS (Dynamic Trailing Sequence): indicates a dynamic frame. CID (Channel Idle Detection): indicates end of comm. (Idle: BP=BM) Data_0: negative differential voltage between BP and BM. Data_1: positive differential voltage between BP and BM. Idle_LP (LowPower): biased to ground. No current to BP or BM. Idle: biased to a voltage. No current to BP or BM. BP (Bus Plus) and BM (Bus Minus) lines used to balance the differential communications network.

44

FlexRay Bus

FlexRay Analysis Application Configure : • Data Source • Probing • Trigger

45

FlexRay Bus

FlexRay Analysis Application Results : • Decoding • CRC Analysis • Correlation to Acq.-Mem

46

FlexRay Bus

FlexRay Analysis Application Results : • Timing Meas. • Sync. Meas. • Eye/Mask Test • TIE • Zoom

47

FlexRay Bus

FlexRay Analysis Application • Real Signals • MASK violation • could be ID related

48