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E a r t h

S p a c e

&

F u t u r e

Kayser-Threde GmbH

V o n d e r E r d e i n s A l l .

U n d z u r ü c k .

Intelligente Lösungen für

Industrie und Wissenschaft.

F r o m E a r t h t o S p a c e .

A n d b a c k .

Intelligent solutions for

industry and science.

Sensor BusWorkshop at ESTEC

Kayser-Threde Contribution

Heinz-Volker Heyer [email protected]

October 7th & 8th, 2003

SCIENTIFIC PAYLOADS

04/15/232 Sensor Bus Workshop at ESTEC, October 7th & 8th BUSINESS UNIT SCIENTIFIC PAYLOADS

Kayser-Threde Experience with Sensor Busses

Illustrated by the following three examples:

Automotive Crash Test System

MINIDAU®

Automotive Crash Test System

MINIDAU®

one-wire bus I2C Bus

Digital Transducer Interface DTI

Digital Transducer Interface DTI

I2C Bus

Automotive Crash Test System MICRODAU®

Automotive Crash Test System MICRODAU®

USB Bus SPI for ADC / DAC / MUX communication


Crash Test Overview


One-Wire Bus (Maxim-Dallas) with MINIDAU®

One-wire bus application in MINIDAU®:

Configuration control of sub-modules (boards, I/Fs etc.)

Low level measurement of temperatures etc.

Identification of connected sensors, cables, and other

equipments.

Benefits of such an internal sensor bus:

Unique identification of all components, modules

Knowledge of the systems basic features (set-ups, temperature, log sheet, etc.)

Knowledge of connected elements for auto configurations, basis for plug and play (Smart sensors IEEE-P1451.4, TEDS Transducer

Electronic Data Sheet).


Bus overview:

Bus with one signal line and return (power transfer included, very low power)

Bi-directional Only one master possible Available in nearly any network topology Unique identification number 48-Bit with 8-bit family code Nodes are only limited by load and transmission speed Simple implementation of master Hot swap capability Automatic identification of connected elements via polling Prioritization for critical signals Data rates 14 kbits/s and 140 kbits/s (1 Mbit/s in preparation) Failure detection via CRC8/16 Many functions and components available as standards

(ADC, Switch, ID, Flash, Temp. etc.)

One-Wire Bus (Maxim-Dallas)


One-Wire Bus (Maxim-Dallas)

One-Wire Bus Configurations

Master

Master

Master

one-wire sensor

one-wire switch

sensor line

Master Master


1-Wire® Devices

4-Channel A to D converter 1

Digital potentiometers 1

Memory: EPROM, SRAM, EEPROM, ROM, NVRAM 16

Memory + GPIO 3

Memory + counters 1

Timekeeping & real-time clocks 3

Temperature sensors and temperature switches 8

Battery protectors, selectors, and monitors 9

1-Wire® interface products 12

USB to one-wire converter

Identification solution


I2C (SM) Bus

I2C (SM) Bus application in MINIDAU®:

Internal data acquisition bus (controller with modules)

System bus for I/O control.

Benefits of such internal sensor bus:

Low pin count on backplane, easy synchronization

Existing tools for testing (adapter for PC)

Independent testing of modules

Easy implementation in FPGAs.


I2C Bus

Bus overview:

Bus with two signal lines and return

Bi-directional

Multi-master possible

Data rates 100 kbits/s, 400 kbits/s and 3.4 Mbits/s high speed mode)

Many functions and components available

Simple implementation of master and slave

7-bit (112 members) or 10-bit (1024 members)

Available as license free SM-Bus.


Digital Transducer Interface

Bus overview:

Bus with two signal lines (I2C based) and a power line with common return

Power: 5V +2%/-0% 200mA

Bi-directional

Coherent data sampling within the complete system

Multidrop capability - up to 14 sensors per bus (limited by cable length and power need)

Data rates 100 kbits/s and 400kbits/s high speed mode)

Only a few functions and components available commercially

Sensor bus of Endevco, VW, and Hentschel for crash tests

I2C depending features

Support TEDS.


USB Bus with MICRODAU®

USB Bus application in MICRODAU®:

Synchronization of all MICRODAUs®

Measurement of data 3 x 16 Bit (20 Ks/s each) and 1 x temperatures etc.

Identification of connected MICRODAUs®

Cluster network with hubs

Benefits of such a sensor bus:

Inextensive wiring (tree topology)

Unique identification of MICRODAUs®

Easy use with each PC computer (plug and play, hot swap etc.)

Synchronization via bus features

Knowledge of connected elements for auto configurations, basis for plug and play (Smart sensors IEEE-P1451.4,

TEDS Transducer Electronic Data Sheet


USB Overview

USB Universal Serial Bus

Speed USB 1.1 1.5Mb/s or 12Mb/s

USB 2.0 480Mb/s

4-wire cable interface 2 x data 2 x power (5 V @ 500 mA per device max.)

Coherent data sampling within the complete system

Up to 127 devices per USB port (bandwidth limitation will reduce this number in practice)

Cable length about 5 m

Easy building of cluster nets with hub incl. power supply


MICRODAU® USB Topology within a Dummy


USB Bus in Crash Link

USB topology sensor modules and hub and wireless connections

Hub

µDAU

µDAU

µDAU

Hub

5V/24V

µDAU

µDAU

µDAU

Hub

5V/24V

Controller

USB 1.1 or 2.0

USB 1.1 or 2.0

USB 1.1 or 2.0


System Performance Overview of MICRODAU®

Bridge excitation : 2.5 V DC

Channels : 3 / 30

Gain steps : 1..1200

ADC resolution : 16-bit

Sampling rate : up to 20 kHz synchronously / channel

Memory : 2 Msamples per channel

(100 sec @ 20kHz sampling rate)

Auto zero : each channel

Shunt check : e.g. 150 kOhm



TEDS (Transducer Electronic Data Sheet) : Yes

Flash memory (non-volatile) : Yes

Bridge completion : Full bridge

Filter : Adaptive anti-aliasing

Data handling : USB-Bus 1.1

Volume per channel : < 4 cm³

Shock : 500 g peak @ 3ms

Vibration : 5.4 g 30 min



Signal conditioning, memory and A/D conversion close to the transducer

High speed data link (4 wires)

256 channels per system

Built-In battery

Seamless integration into existing MINIDAU® products via CrashLink® hub

Support for most dummies (including WorldSID)

In-dummy data acquisition and stand-alone system

Data acquisition front-ends with three channels


MICRODAU® Outline and Topology

Hub architecture

MICRODAU®

MICRODAU® Components


Conclusion

There is a hierarchy of busses needed in a complex system, e.g.:

one-wire bus for low level measurement and configuration, identification

(very simple)

a more powerful standard serial bus such as I2C or USB (USB preferred) which

manages the necessary data rate (should preferably include also power supply).

Use of commercially widely available bus standards (hardware and software).

Combination with wireless data acquisition systems (upgradable) is desirable.

From the KT experiences such architectures could be recommended for future

spacecrafts and payloads, since they offer sophisticated cabling concepts together with

low weight, tiny size, and low power consumption.


Thank you very much

for your attention

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