midterm review 2006-04-11 1 mbs 2006 mp electronics, basic concept two modules: probe module ...
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MP Electronics, Basic Concept
Two modules:
Probe module
Surface module
The surface module is replaced by the Interface Module and COTS components
Detailed data processing is performed by the surface module (GSE)
Controller inside probe module performs measurement and heater control tasks
Power supply and communication via the tether
Power provided by standard laboratory power supply
Standard interface for communication: USB
In terface M odule
Probe M odule
Laboratory Power Supply
Tether
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MP Electronics Module (1)
Dedicated electronics department inside the probe
Cylindrical tube with top and bottom cover
Three braces at 120° position provide the fixation of the PCB's
Braces are used to fix the electronics compartment inside the probe
Fixed connector at top cover provides the interface to the tether
Pig-tails (TBC) located at the bottom cover provide the interface to the heaters and sensors
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MP Electronics Module (2)
Power conditioner
Controller
Communication
Signal conditioning
Heater Control
M elt in g Pro b e Electro n ics
DC-DC5 Volts
ControllerCommunication
Heater Control
Signal Conditioning
D +
D -
Hea
ter
1
Hea
ter
5
Tether
Pt1
00 1
Pt1
00 9
P H S ensor
Two A xisTilt S ensor
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MP Electronics Module (3)
Circuit diagrams not fully completed Electronics will be spread to 5...6 PCB's (55mm diameter) Connection to tether and external heaters and sensors via MDM
connector PCB interconnection via spring contacts and gold plated pads
M elt in g Pro b e Electro n ics
Power Module
Communication Module
Heater Control Module
Controller Module
Pt100 S ignal Conditioner
Sensor ModulePH, Tilt, 28V, 5V
2 2
T ether
5V
28V
28V Return
5V Return
2
2
5
5x 2
10
9x3 + 1
Heater 1
Heater 5
Pt100_1
Pt100_9
4
3
2
PH3
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Power Conditioner
Supply via the tether with 28V (laboratory power supply)
Use of two redundant pairs (AWG ?)
High power Schottky diodes at +28V input
Heaters directly supplied from 28V
DC/DC converter 28V / 5V to supply electronics
Linear regulator to generate supply voltage for Ph sensor
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Controller
Prototype is based on PIC18F4550
Frequency: up to 40MHz, inbuilt 8MHz clock
Program memory: 32KByte
Data memory: 16kByte
ADC: 10 bit, 13 channels, 5V range
On-chip USB interface
44-pin TQFP plastic package
Operational temperature range: -40°C...+85°C
Storage temperature range: -65°C...+150°C
Wide supply voltage range
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Communication
The communication channel uses the same signal lines as the power supply
Binary frequency shift key modulation for signal transmission will be used
Use of two carrier frequencies to support full-duplex mode
The communication will be based on the USB protocol
Frequencies not yet selected
Detailed design not yet finished
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Heater Control
Large variation of impedance due to environmental condition Individual current limiter for each heating segment Power management to minimize EMC radiation and losses
Heating segments switched sequentially
Concept for power sharing in low power mode under investigation
Control loop activated every 10ms (TBC) Dedicated bang-bang controller with adjustable nominal
temperature for each segment Highest priority is given to front segment, while rear segment
has lowest priority Electronics calculates duty-cycle for each heater segment
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Temperature Measurement
Measurement shall support a temperature range between -200°C and +100°C
Five Pt100 are dedicated to the heater segments, four additional sensors are available for individual measurements
Pt100's are supplied with constant current of 1mA
Four wire interface is important since impedance of Pt100 varies from approx. 20Ω to 140Ω
Common GND line to save connector pins (three wire interface)
Resolution approx. 0.5°C/digit
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Analogue & Digital Measurements
C h a n n e l S ig n a l R a n g e Vo lta g e R e m a rk
AC H 0 1 P t 1 0 0 H e a te r 1 -2 0 0 ...+1 0 0 °C 0 .1 ... 4 .9 V U se d fo r co n tro l lo o p
AC H 0 2 P t 1 0 0 H e a te r 2 -2 0 0 ...+1 0 0 °C 0 .1 ... 4 .9 V U se d fo r co n tro l lo o p
AC H 0 3 P t 1 0 0 H e a te r 3 -2 0 0 ...+1 0 0 °C 0 .1 ... 4 .9 V U se d fo r co n tro l lo o p
AC H 0 4 P t 1 0 0 H e a te r 4 -2 0 0 ...+1 0 0 °C 0 .1 ... 4 .9 V U se d fo r co n tro l lo o p
AC H 0 5 P t 1 0 0 H e a te r 5 -2 0 0 ...+1 0 0 °C 0 .1 ... 4 .9 V U se d fo r co n tro l lo o p
AC H 0 6 P t1 0 0 -2 0 0 ...+1 0 0 °C 0 .1 ... 4 .9 V
AC H 0 7 P t1 0 0 -2 0 0 ...+1 0 0 °C 0 .1 ... 4 .9 V
AC H 0 8 P t1 0 0 -2 0 0 ...+1 0 0 °C 0 .1 ... 4 .9 V
AC H 0 9 P t1 0 0 -2 0 0 ...+1 0 0 °C 0 .1 ... 4 .9 V
AC H 1 0 P t1 0 0 E le ctro nics -2 0 0 ...+1 0 0 °C 0 .1 ... 4 .9 V
AC H 1 1 PH se n so r
AC H 1 2 2 8 Vo lts
AC H 1 3 +5 Vo lts
C h a n n e l S ig n a l R a n g e C o u n te r R e m a rk
D C H 01 T ilt sensor X T1 0...1 0m s D uty cyc le
D C H 02 T ilt sensor X T2 0...1 0m s Total period
D C H 03 T ilt sensor Y T1 0...1 0m s D uty cyc le
D C H 04 T ilt sensor Y T2 0...1 0m s Total period
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Communication Protocol
Data are sent only on request
A response is send for each command, either simple ACK/NACK or data-set
Commands:
Set the nominal value for the control loop
Requests the temperature values
Requests all measurement values
Requests the nominal temperatures for the control loops
Request duty cycle
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 H eader C om m and
Length C om m and Identifie r
Param eter 1 Param eter 2 Param eter 3
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Data-Set
Acknowledge / Not acknowledgeNACK will include simple failure code
Temperature dataThe temperature value for all five heater segments
All measurement dataA complete of measured data, temperatures, tilt angles and Ph value
Nominal temperature valuesRead-back of the reference values for the heater control loops
Duty cycleActive time of a heater during 1sec time periodResolution 1% (TBC)Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte
2N +6
xx PacketLength = 6+2N
C m d-ID + AC K
N O_Error
Spare Spare Value 1 H igh byte
... Va lue N Low byte
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6
H eader 06 C m d-ID + AC K Error code or N O_Error
Spare Spare
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Software Design
Design based on Ward-Mellor method
Implementation with the MPE Lab IDE
Coding in C based on the Microchip C18 compiler
USB driver provided by Microchip
Measurement of analogue signals (Pt100 & Ph) by use of inbuilt ADC
Measurement of digital signals (tilt sensor) by use of capture/compare registers
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Software Interfaces
In te rn a l H W In te rru p ts
P ro g ra m m Fla sh-PR OM
0M elting P robe SW
U SB In te rru p ts
U SBSta tu s & C o n tro l R e g iste rs
U SB R AM
ADC Interface
USB-Interface
PIC 1 8FxxxS ta tu s & C o n tro l R e g iste rs
In te rn a l H WC o n tro l R e g iste rs
internal HardwareT im er, H LVD , ...
CCP/PWM Interface
Po rt x
I/O Ports
AD C In te rru p ts
AD CSta tu s & C o n tro l R e g iste rs
AD C R e su lt R e g iste r
9 x Pt100, 1 x PH sensor, 1x 28V, 1X 5V
C C P/PW M In te rru p ts
C C P/PW MSta tu s & C o n tro l R e g iste rs
Tim e r R e su lt R e g iste r
2 x T ilt sensor
5 x H eater On / Off
C CP / PW M
Inter rupts
PIC 18F xxxC ontro l & Status
In te rn a l R AM
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Software, Decomposition Level 0
2Communicate
via USB
4Measure
3Control Heaters
1ControlSystem
AD CInterruptsA DCCo ntr ol & Sta tusAD CR es ult
I/O Por t
C CP / PWM
Inter rupts
CCP / PW M
C on tro l & S tatu s
PW M
Result
USB
In terr up ts
U SBC ontro l & Status
U S BDa ta
in te rnal HW
IR Q s
F lash-PR OM data
Internal HW
C ontrol & S ta tus
P IC 18Fx xx
C ontro l & S tatus
In ternalRAM
M easured D ata
C om m anded D ata