Midterm Review MBS 2006 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

Midterm Review MBS 2006 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

Midterm Review MBS 2006 MP Electronics Module (2)  Power conditioner  Controller  Communication  Signal conditioning  Heater Control

Midterm Review MBS 2006 MP Electronics Module (3)  Circuit diagrams not fully completed  Electronics will be spread to PCB's (55mm diameter)  Connection to tether and external heaters and sensors via MDM connector  PCB interconnection via spring contacts and gold plated pads

Midterm Review MBS 2006 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

Midterm Review MBS 2006 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 °C  Wide supply voltage range

Midterm Review MBS 2006 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

Midterm Review MBS 2006 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

Midterm Review MBS 2006 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

Midterm Review MBS 2006 Analogue & Digital Measurements

Midterm Review MBS 2006 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

Midterm Review MBS 2006 Data-Set  Acknowledge / Not acknowledge NACK will include simple failure code  Temperature data The temperature value for all five heater segments  All measurement data A complete of measured data, temperatures, tilt angles and Ph value  Nominal temperature values Read-back of the reference values for the heater control loops  Duty cycle Active time of a heater during 1sec time period Resolution 1% (TBC)

Midterm Review MBS 2006 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

Midterm Review MBS 2006 Software Interfaces

Midterm Review MBS 2006 Software, Decomposition Level 0