Hardware Challenges and Their Resolution in Advancing

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Authors:
Xiuming Zhu1, Song Han1, and Aloysius Mok1
1The Department of Computer Science, the University of Texas at Austin
Deji Chen2, and Mark Nixon2
Presenter:
2Emerson
Process Management
Yi-Hung Wei1

Wireless Personal Area Network(WPAN)
◦ IEEE 802.15.4
◦ ZigBee

Industrial Wireless Network
◦ Timing requirement, reliability, security concerns
◦ WirelessHART
 IEEE 802.15.4
 Hardware challenges
2003
2004
IEEE 802.15.4
2005
ZigBee
2006
2007
WirelessHART
2008
2009
FreeScale MC1322
Real-Time
◦ TDMA Technology
◦ Centralized Network Management
Reliability
◦ Channel Hopping and Channel Blacklisting
◦ Mesh Networking
Security
◦ Data Integrity on MAC Layer
◦ Data Confidentiality on the Network Layer
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
IEEE 9th International Conference on Industrial Informatics, INDIN'2011


Hardware Challenges
Development of WirelessHART
◦ Early Prototype
◦ Wi-HTest
◦ Current System

Future work
IEEE 9th International Conference on Industrial Informatics, INDIN'2011

TDMA data link
layer
 Timeslot: 10ms
 TsTxAckDelay: 1ms

Security mechanism
 MAC layer related
processing
 Authenticate the
incoming message
 Generate authentication
code
WirelessHART Slot Timing
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
Data Link Layer Minimum Requirement
Device
Tiny
Gateway
Large
Gateway
Neighbors
32
12
128
Superframes
16
12
12
Total # of
Links
Graphs
64
50
32
25
Network Layer Minimum Requirement
Device
Tiny
Gateway
Large
Gateway
Sessions
8
30
510
1 per Session
1 per Session
16
500
Correspondent
Device
Transport
2 per Session
30
510
128
Routes
8
15
128
Total # of
GraphNeighbor pairs
Packet Buffers
128
40
1000
Source-Routes
2
16
25
500
Timetables
16
N/A
N/A
Total size
6,112 bytes
5,716 bytes
11,6356
bytes
Total size
1,106 bytes
2,910 bytes
36,508 bytes
IEEE 9th International Conference on Industrial Informatics, INDIN'2011

WirelessHART network is a synchronized
network
◦ 10ppm drift rate of the MCU clock.
◦ The maximum tolerance for drift is 1ms
 Synchronize every 50secs between master and slave.
 If the chain from time source is longer, the time to
sync is shorter.
IEEE 9th International Conference on Industrial Informatics, INDIN'2011


Hardware Challenges
Development of WirelessHART
◦ Early Prototype
◦ Wi-HTest
◦ Current System

Future work
IEEE 9th International Conference on Industrial Informatics, INDIN'2011

802.15.4 chips available in early day
Manufact Chip
urer
Ember
EM250
FreeScale
Jennic
TIChipcon
MCU
16bit
24MHz
MC13214 8bit
40MHz
JN5121
32bit
16MHz
CC2430
8bit
32MHz
Max tx
Flash
RAM
5dBm
128k
5k
3dBm
60k
4k
0.4dBm
64k (ROM) 96k
0.6dBm
128k
8kb
* J. Song, S. Han, A. K. Mok, D. Chen, M. Lucas, M. Nixon, and W. Pratt, WirelessHART: Applying
Wireless Technology in Real-Time Industrial Process Control. Real-Time Technology and
Applications Symposium, 2008.
* J. Song, S. Han, X. Zhu, A. K. Mok, D. Chen, and M. Nixon, Demo of a Complete WirelessHART
Network, ACM SenSys 2008 Demo Session.
IEEE 9th International Conference on Industrial Informatics, INDIN'2011

Some observations
◦ MCU
 Only tested with 20ms, 40ms timeslots
◦ Software AES engine
Hardware
 MC1321 software AES engine AES
◦ Transmitter
 Maximum programmable transmit power is only 3dBm
◦ RAM
 4KB is too limited
IEEE 9th International Conference on Industrial Informatics, INDIN'2011


Hardware Challenges
Development of WirelessHART
◦ Early Prototype
◦ Wi-HTest
◦ Current System

Future work
IEEE 9th International Conference on Industrial Informatics, INDIN'2011


Motivation
◦ Assure the standard compliance of WirelessHART devices
◦ Thorough tests for each layer of WirelessHART stacks are
needed
◦ Help vendors avoid expensive product recalls and technical
support costs
Hardware architecture
◦ FreeScale MC1320
 Physical layer, data link layer
 ColdFireV1 MCU, 32-bit, 50.33MHz
 128KB FLASH
 16KB RAM
◦ PC Box
 Network layer
S. Han, J. Song, X. Zhu, A. K. Mok, D. Chen, M. Nixon, W. Pratt, and V. Gondhalekar, WiHTest: Compliance Test Suite for Diagnosing Devices in Real-Time WirelessHART Network.
Real-Time Technology and Applications Symposium, 2009.

Clock precision
◦ ±2.5ppm oscillator as the external clock input
◦ The drift is consistent in fixed environment
 It is possible to compensate it with software

Security computation
◦ CCM algorithm is still expensive
 Parallel decoding
◦ Pre-compute acknowledgement message

Flash Memory Usage
Compone
nt
Bootload
er
CDC-USB
driver
Encryptio
n engine
System
library
Operatin
g system
WirelessHAR
T stack
Total
3K
11K
20K
11K
7K
34K
86K
IEEE 9th International Conference on Industrial Informatics, INDIN'2011


Hardware Challenges
Development of WirelessHART
◦ Early Prototype
◦ Wi-HTest
◦ Current System

Future work
IEEE 9th International Conference on Industrial Informatics, INDIN'2011

Hardware
◦ FreeScale MC1322







32-bit 24MHz ARM7 MCU
22mA typical RX current draw
29mA typical TX current draw
Extensive sleep mode
MAC accelerator
Advanced AES hardware engine
Software
◦ Complete WirelessHART mesh networking
functionality
IEEE 9th International Conference on Industrial Informatics, INDIN'2011



10 devices and 1 AP in the
system
Devices publish data to GW with
different sampling rates (1sec –
8sec)
Retry happens but no packet
loss is detected
17


Hardware Challenges
Development of WirelessHART
◦ Early Prototype
◦ Wi-HTest
◦ Current System

Future work
IEEE 9th International Conference on Industrial Informatics, INDIN'2011

Memory
 96K Flash for
WirelessHART stack
 24K RAM for the data
section
 More space for
application layer

Clock
 High precision
 Maintains precision
when sleep

Power
 More sensitive receiver
 More deeper sleep
mode

Encryption
 Hardware AES engine or
fast MCU
 Open AES engine
IEEE 9th International Conference
on Industrial Informatics,
INDIN'2011

Chronicle our work and provide our
experience of the system design challenge of
WirelessHART
◦ Prototype
◦ Wi-Htest
◦ Complete WirelessHART mesh network

Provide hardware requirement for future
industrial wireless embedded network chip
IEEE 9th International Conference on Industrial Informatics, INDIN'2011
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IEEE 9th International Conference on Industrial Informatics, INDIN'2011
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