Delphi and the DS502 NEXUS Interface - dSPACE

Delphi and the DS502 NEXUS Interface 

Mark M c Farland and Rick Skertic 

Slide #1 

Delco Electronics Systems

Introduction 

Delphi has been using Rapid Algorithm Development (RAD) 

tools in its standard tool chain to develop new application for 

several years. Most of this work has been done using the 

Algorithm Bypass processes. The interface between the ECU 

and the Autobox or MicroAutobox has traditionally been done 

using a Dual Port Memory (DPM) board. Due to the fact that 

Delphi uses a wide spectrum of processors we have had to 

develop several DPMs each with its own test connector and 

mechanical configuration. 

With the event of the NEXUS debug port Delphi saw the 

opportunity to make this the universal tool interface for 

calibration, debug, and RAD. dSPACE and Delphi jointly 

worked to created the DS502 in order to use the NEXUS port 

for RAD applications. 

Slide #2 


DS502 Front View 

Slide #3 


DS502 Side View 

Slide #4 


DS502 Features 

! Standardized robust Nexus connector 

! Wide input operating range 4.8 to 32V 

! 26V jumpstart protection 

! Isolated power supply to prevent ground loops. 

! Passthrough connector for multiple tool connection 

! Interrupts can be generated through watchpoints or the EVTO 

pin. 

! Protection buffers to prevent power moding problems with the 

ECU 

Slide #5 


Configurable Development System (CDS), 

DS502 & Debugger 

Slide #6 


Development Tools 

! CDS 

– The CDS is a rapid prototyping hardware platform used by Delphi to meet 

customer demands for quick turns on proto-hardware. This unit utilizes a variety 

of drop-in processor cards to meet customer requirements. 

! DS502 

– The DS502 provides RAD support for multiple processors and therefore helps to 

preserve the tool chain while different solutions, to the customer requirements, 

are evaluated. 

! Debugger 

– NEXUS debuggers are supplied by Ashling, Lauterbach, and WindRiver. 

Slide #7 


Interrupt Latency 

! The DS502 supports the interrupt process using either 

watchpoint messages or the EVTO line. 

! Interrupt latency was measured at ~24uS. 

– This was measured using a simple model that increments a signal input and 

writes it back. 

Slide #8 


Data Exchange Rates 

! The Nexus port has non-intrusive access to the CPU’s bus, in 

most cases.This allows data to be exchanged without the ECU 

having to run special code. The NEXUS port can access this 

data as either discrete elements or as a block of data. The 

access of data in blocks is faster but the flexibility of the discrete 

element approach has its own advantages. 

! It should be noted that the data rate is directly tied to the 

operating frequency of the processor. In the Power PC the 

request going into the processor are clocked at 1/2 the CPU’s 

clock rate and the data coming out of the CPU is clocked at the 

CPU’s clock rate. 

! The data rate is also dependant on the number of pins used to 

transfer the information. The MPC565 NEXUS port support 1 or 

2 input pins and 1 or 8 output pins. 

Slide #9 


Discrete Element Data Exchange Rates 

! When using the NEXUS port to exchange individual pieces of 

data each read requires 6.8 uS and each write requires 21.7 uS 

on average. 

– Processor running at 40 MHz. 

! The process of performing the RAD process adds an overhead 

of 80.3 uS to the process. This includes interrupt latency and 

communications processes. 


! The actual time needed to perform the algorithm has to be 

added to the above numbers. 

! By accessing the data as discrete elements the developer has 

the highest degree of freedom in specifying the data to be 

exchanged. Because the data is written directly to the 

parameter locations in the ECU, there is little overhead in the 

ECU to support the process. 

Slide #10 


Discrete Block Data Exchange Rates 

! When using the NEXUS port to exchange blocks of data each 

read requires 0.608 uS and each write requires 3.3 uS on 

average. 


! The process of performing the RAD process adds an overhead 

of 80.3 uS to the process. This includes interrupt latency and 

communications processes. 


! The actual time needed to perform the algorithm has to be 

added to the above numbers. 

! By accessing the data as blocks the highest throughput rates 

can be achieved, but there is a higher impact to the ECU. The 

data either has to be blocked by the software engineer ahead of 

time or code has to be added to the ECU to distribute the data. 

– Blocking the data is inflexible and requires constant maintenance. 

– When generic hooks are implemented to distribute the data both processors 

cycles and ECU resources are used. 

Slide #11 


Robust Test Connector 

! The NEXUS committee officially approved the 51 pin test connector that 

Delphi proposed as the Nexus Connector type “C Robust” in the 1.5 version 

of the specification which will be made public before June 2002 

! This connector has the following features 

– Supports up to 2 data inputs and 8 data outputs. 

– Supports 150 MHz. operation. 

– Mechanically sound for the in-vehicle environment. 

– Small mechanical footprint. 

– This 51 pin interface is robust enough to meet the needs of the in-vehicle environment. 

» Temperature 

» Vibration 

» Mating 

– Same connector can be used for both Nexus and OCDS. 

– A significant number of grounds are present for de-coupling. 

Slide #12 


Delphi’s Bypass-Technique 

Processor Resource Impact 

! FLASH Image 

– Communications Code 

» ~512 bytes 

– Algorithm Hooks 

» ~20 bytes pre algorithm 

! RAM Image 

– Stack 

» ~40 bytes per interrupt that is active 

– Communications Area Discrete Access 

» ~64 bytes 

Slide #13 


Delphi’s Bypass-Technique 

Processor Resource Impact 

! RAM Image (continued) 

– Communications Area Block Access 

» The size of the area is directly dependent on the amount of data that is to be 

exchanged and how intrusive the process is into the development process. 

! Least Intrusive 

– 255 bytes 18 Parameters exchanged 



! Most Intrusive 



– 1024 bytes 450Parameters exchanged 

Slide #14 


DS502 Features 

! The DS502 supports a passthrough connector for the NEXUS bus allowing 

other tools access to the bus. 

Slide #15 


Tools 

! Delphi has been using a configuration tool that allows the user 

to graphically associate model parameters to ECU parameters. 

– Configuration control 

– Automatically re-associates model parameters with ECU parameter with each 

compile. 

– Creates theDS502 setup file for the user. 

– ASAP II compatible 

Slide #16 


RAD Configuration Tool 

Slide #17 


DS 502 Demo 

! This Demonstration is being done with the MPC565. 

! The process is monitored by the Delphi Calibration Tool, the 

Instrumentation Tool Set (ITS) using a CAN Calibration Protocol 

(CCP) link. 

! This demo will show the following features. 

– Soft Start / Stop 

– Bypass 

– Tap 

– Replace 

– On the fly algorithm switching 

Slide #18 


ControlDesk 

Slide #19 


Advantages 

! The 51 pin NEXUS connector can be used both as the universal 

tool interface and as the interface to production units. 

– Reprogramming 

– Data Acquisition 

– System Diagnostics 

– RAD Work 

» When this interface is available on a production ECU, RAD work can be 

started immediately for the software of carryover programs. 

! Cost effective solution for application that run 6.25 mS or 

greater cycle times using the following criteria. 

– %5 throughput hit for the process. 

– Exchanging 50 parameters between the ECU and the RPS. 

! The DS502 can be used across several processor families so 

the same tool chain can be used on many different projects. 

– Motorola SPS Power PC 

– Infineon Tricore 

Slide #20 


Advantages 

! Because the NEXUS port allows the RAD System to directly 

access any location in the ECU memory map, the data that is to 

be processed can be very flexible. The user can redefine what 

ECU RAM data is to be used by the processor at any time. The 

skilled users can also access the peripherals that are available 

to the ECU. 

! Because the ECU doesn’t have to handle the moving of the 

data, the hooks that the ECU runs are streamlined. 

– Lower impact to available FLASH 

– Less software maintenance 

! This process can be used on “off the shelf” development 

boards. 

– This means that the RAD process can be started earlier in the development 

phase. 

Slide #21 


Disadvantages 

! The NEXUS port will steal cycles in some cases that can effect 

the timing of some code. 

! Slower data acquisition rates don’t support some applications. 

! The access cycles used by the MPC565 NEXUS port show up 

on the logic analyzer and have to be manually processed by the 

user. 

– This issue has been brought to Motorola’s attention 

! All tools can’t access the the NEXUS port at the same time. A 

port arbitration protocol needs to be implemented. 

– Currently being addressed by the IEEE ISTO-Nexus5001 Forum, Software Subcommittee 

Slide #22 


! The DS502 allows one tool to be used across multiple 

processor families.This streamlines the cost of the tools 

themselves,but also cuts cost by removing learning curve 

issues. 

Conclusions 

! The NEXUS interface also allows for more generic, less 

intrusive hooks. This allows hooks to be ported from program to 

program with less maintenance. 

! The NEXUS interface is more that fast enough to handle 80% of 

all RAD work being done on automotive engine controllers. This 

allows for a common interface to be used over may programs 

simplifying the tool availability issues. 

Slide #23

Delphi and the DS502 NEXUS Interface - dSPACE

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