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TRANSCRIPT
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Questionaire DPS AEE14
WS2015/16
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Contents 1 PCB Board Manufacturing (Drofenik) ............................................................................................... 4
1.1 Name five different types of Rigid Printed Circuit Boards! ................................................... 4
1.2 Draw a schematic illustration of a cross-section of a double sided PCB and a 6-layer
Multilayer PCB. .................................................................................................................................... 4
1.3 Describe the process flow of a 4-layer printed circuit board from inner layer processing to
electrical test. ....................................................................................................................................... 5
1.4 Describe the principle difference between following Microvia-formation processes:
UV/CO2 vs Conformal mask vs Laser direct ..................................................................................... 11
1.5 Describe the function purpose of a Printed Circuit Board. ................................................. 12
2 PCB Board Design (Weis) ................................................................................................. 12
2.1 Show a design process starting at the idea until the finished PCB ................................... 12
2.2 Draw a sketch of a 6layer PCB and insert all possible via constructions .......................... 14
2.3 What are the design rules necessary for? Who should be asked for a ruleset and when do
you have to set it up in your design suite? ........................................................................................ 14
2.4 How can a power plane be connected? Name advantages and disadvantages of the
different connect styles. ..................................................................................................................... 15
2.5 What is embedding? Draw a sketch. Which constructions are possible? ......................... 15
3 AUTOSAR (De Meulenaer) ................................................................................................ 17
3.1 Draw the AUTOSAR layered software architecture, and explain briefly the functionality of
each of the layers. ............................................................................................................................. 17
3.2 What is a client-server interface and what is a sender-receiver interface? Discuss their
properties and differences in the context of AUTOSAR. ................................................................... 18
3.3 Give a brief overview of the AUTOSAR software development process. Also explain the
relationship between the AUTOSAR development process and the Vmodel. .................................. 19
3.4 What is "relocatability of software components"? Explain the concept and give an
example. 21
3.5 AUTOSAR software components are relocatable, i.e. they can be put on another ECU
without impact on the application design. Which AUTOSAR architecture concepts guarantee this
relocatability? Explain your answer. .................................................................................................. 22
3.6 What is the difference between an OSEK basic task and an OSEK extended task? Make a
drawing and explain. .......................................................................................................................... 23
3.7 What is 'pre-emption of a task'? Explain and give an example.......................................... 24
3.8 What is the VFB, and what is the RTE? Describe them briefly, and discuss their analogies
and differences. ................................................................................................................................. 25
3.9 What is a "runnable"? What kinds of runnables do you know? Explain them. .................. 26
3.10 What AUTOSAR mechanism converts runnables into a tasks? Discuss the possible
technical options. ............................................................................................................................... 27
3.11 Which kinds of messages are defined in OSEK (and therefore also in AUTOSAR)? And
how do they match to properties of message queues? Explain. ....................................................... 28
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3.12 E.Platform-independent software is less platform-independent as one might expect. Give
two examples that prove this statement in the context of automotive embedded software. ............. 29
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1 PCB Board Manufacturing (Drofenik)
1.1 Name five different types of Rigid Printed Circuit Boards!
Rigid Boards – Standard:
Single Sided (Print & Etch)
o Standard
o Crossover
Double Sided
o Non plated through
o Plated Through Hole (PTH)
Multilayer (up to more than 60 layers)
o Standard
o Blind via and PTH
o 1-N-1 Blind & buried via & PTH
o 1-N-1 Blind & buried via
o 2-N-2 stacked & buried via
Anylayer
HDI – High Density Interconnection
Substrates
Rigid Boards – Special:
Silver cross-over
Copper Inlay
HDI - FV; ALIVH; 2,5D; Bare Die HDI
1.2 Draw a schematic illustration of a cross-section of a double sided PCB
and a 6-layer Multilayer PCB.
Double sided PCB
Non plated through
Plated Through Hole (PTH)
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6-layer Multilayer PCB
Standard
Blind via and PTH
1.3 Describe the process flow of a 4-layer printed circuit board from inner
layer processing to electrical test.
Photo Process (inner layer)
o Precleaning: Removes oxidation and residues from surface and creates micro
roughness
o Lamination: Laminates a photosensitive dryfilm on the panel
o Exposing: Exposes the PCB layout on the photosensitive resist by using a photo
tool and UV light.
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o Developing: All resist areas which were not exposed to UV light will be washed off
→ we get exposed copper areas and areas where we still have resist on the board
o Etching: All areas with exposed copper will be etched away
o Stripping: The resist which was exposed to UV light is still on the board and will be
stripped off in this step → we get the finished PCB layout
AOI (Automatic Optical Inspection)
The layout on the board is scanned. During verification we compare the scanned image
with the customer original layout. Thereby the camera points out all positions where we
have a mismatch automatically. The operator verifies if it is a defect or just some dust or
stain.
o Scanning front: Scanning of actual layout of the panel
o Scanning back: Scanning of actual layout of the panel
o Verification: Compare scanned image with original data and point out all
mismatches
Relamination
o Alpha Prep: Creates more rough surface and provides an organic layer on the PCB
which works as a kind of “glue”
o Lay-up: We take all layers of the PCB and build a stack according to the build-up.
o Relamination (Press): We take the stack prepared by lay-up and press it together
under a certain pressure and temperature.
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o IBL: Cuts of the excess cooper on the edge of the board, thickness check of each
board and lotnumber stamping.
Mechanical drilling
o X_Ray Drilling: “X-Rays” panel and drills tolling holes for mechanical drilling. The
scaling value is calculated in this step.
o Mechanical drilling: Mechanical drilled holes from top to bottom (through all layers -
hole diameter from 0.2 to 4mm.
o Deburring: Removes the burr around the drill hole.
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Laser drilling, direct cooper
o Black oxide: To get a rough and black surface for the laser
o Laser Drilling: A CO2 or combined CO2/UV laser drills the holes through cooper
and dielectric.
o Black Oxide Removal: Removes the remaining black oxide.
Cooper plating
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o Deasmearing: Cleans the holes and swells the resin to get more surface roughness
o Chem Cooper: A thin layer (0.5μm) of copper is plated in the holes by chemical
reaction to get a conductive surface.
o Galvanic Plating: A layer of min. 25μm cooper is plated in the holes and on the
surface by applying current onto the board.
Photo Process (outer layer)
Another photo process is needed to get cooper structures on the outer layer s of the PCB.
The process steps are the same as in the first phot process.
AOI (Automatic Optical Inspection)
Another AOI is done.
Solder mask
In this step a solder mask is added to the PCB. That is the green color which most boards
are colored with, it can also be another color.
o Precleaning: Cleans the surface from oxidation and creates a rough surface.
o Coating: Whole panel is coated with solder mask ink in curtain coating or screen
printing.
o Exposing: All areas which should be covered with solder mask are exposed to UV
light by using a photo tool.
o Developing: All areas which were not exposed to UV light are washed off.
o Curing: Final hardening of the solder mask in the oven.
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Routing
In this process step the production format of the PCB gets split up to a smaller customer
delivery format.
o Scoring: If required we add a “V-Cut” on the board.
o Routing: Separates the delivery units from our internal production format and
creates the outline of the card.
o HPR: Removes the routing dust from the board by high pressure rinsing
E-Test / Final Inspection
o E-Test: All connections on the boards are tested for open and short.
o Surface Finish: Covers all exposed cooper areas with the respective surface finish.
o FI: 100% visual inspection, thickness-, coplanarity-, drill diameter check,… on
sample basis.
o QC: Visual inspection, sample check – according AQL.
o Packaging: Packaging according customer requirement.
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1.4 Describe the principle difference between following Microvia-formation
processes: UV/CO2 vs Conformal mask vs Laser direct
UV/CO2 process
First the outer cooper layer is removed by UV-laser, then the resin is removed by CO2-laser
to the next cooper layer.
200 drills / second
Advantage: No additional registration necessary
Disadvantage: 2 lasers in one machine → expensive process
Conformal mask process
The cooper layer is opened by lithographic process and etching. The resin is drilled with
CO2-laser.
Advantage: Cheaper than UV/CO2 process
Disadvantage: The diameter is fixed by photolithography / due to cooper opening
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Laser direct / direct cooper process
Cooper and resin are removed by laser
80 drills / second
Advantage: No capacity loss at photo, no registration issue
Disadvantage: Slow
1.5 Describe the function purpose of a Printed Circuit Board.
A PCB delivers an opportunity to assemble and produce electronic circuits → components
like resistors, capacitances or integrated circuits can be mounted on it
It provides the electrical connections on the board
The components can be cooled by heat dissipation over cooper areas respectively by
mounting cooling components on the board.
It can be said that nowadays nearly every electronic device contains at least one PCB
For example the motherboard of a PC can also be called main PCB – furthermore devices
like smartphones, tablets… have a main PCB which provides the connections between all
important parts of the device (processor, graphics board, speaker…)
2 PCB Board Design (Weis)
2.1 Show a design process starting at the idea until the finished PCB
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Idea
Brainstorming
Schematic development:
Development
Calculation
Simulation
Component selection
Power Supply
Microcontroller
Sensor unit
Mechanical design & Housing
Database
It is important to have a clear structure respectively to follow the signal flow from the left
upper corner to the right lower corner.
Open connections have to be checked
As much information as possible has to be offered, but no overload
Use A3 format as standard
Fill in the title block in the lower right corner
Design verification (documentation with according calculation)
Review schematic (meeting with specialists who are not involved in project)
Schematic connection: Wire / Net (global net) / Bus
Schematic to PCB
Check schematic
Create netlist
Load into PCB
Board design process
Define stack up
Define rule set
Define outline
Place components
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Route
Check PCB
Review meeting
Data output
(Manufacturing data, BOM,P&P)
Manufacturing
Test
Release
2.2 Draw a sketch of a 6layer PCB and insert all possible via constructions
2.3 What are the design rules necessary for? Who should be asked for a
ruleset and when do you have to set it up in your design suite?
Design rules are necessary that the manufacturer is able to produce the PCB. They include
limits which could be produced by a specific manufacturer.
The desired manufacturer has to be asked for the according ruleset.
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The rules have to be prepared / set up in your design suite
before PCB design starts!
The design (PCB) has to be checked according to the Design rules (DRC = Design Rule
Check) after routing
2.4 How can a power plane be connected? Name advantages and
disadvantages of the different connect styles.
Power connection
Delivers a better electrical connection (more area → less resistance)
The current flowing through the connection can be higher as the trace is broader
The power connection has also small heat resistance → the temperature is lead away from
the connected pins → a lot of heat is necessary to solder the components
All pins have a good connection to the power plane
Thermal connections
The electrical connection is not so good as the power connection because there is more
resistance
The current has a restriction
The heat resistance is higher, soldering is easier (not so much heat necessary)
Pins are clearly visible
2.5 What is embedding? Draw a sketch. Which constructions are
possible?
Embedding means that electronic components like transistors or integrated circuits are
implemented into the PCB board.
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Advantages:
Water proof
Thinner PCB
Reduced space
Low impedance connections
Reliability
Double side chip connection
High frequency parts shielded
Disadvantages:
Higher price
Availability of components
Copper pads on die
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3 AUTOSAR (De Meulenaer)
3.1 Draw the AUTOSAR layered software architecture, and explain briefly
the functionality of each of the layers.
Application layer
All AUTOSAR software components, application components and sensor / actuator software
components are located here.
Microcontroller
Hardware
AUTOSAR basic software
It is configured for dedicated ECU hardware functionality used in AUTOSAR applications.
Microcontroller abstraction layer: Is the lowest software layer of the basic software. It contains
internal drivers which are software modules with direct access to the μC internal peripherals and
memory mapped μC external devices.
It abstracts the μC from the above layers to make the higher software levels independent
from the μC.
Complex drivers: This layer is used for complex functions not found on other layers. It accesses the
μC directly.
It fulfills special functions and timing requirements needed to operate complex sensors and
actuators.
ECU (Electronic Control Unit) abstraction layer: It interfaces the drivers from the Microcontroller
Abstraction Layer and also contains drivers for external devices. It offers an API (Application
Programming Interface) to access peripherals and devices regardless of their location (μC internal /
external) and their connection to the μC (port pins, type of interface).
It makes higher software layers independent of the ECU hardware layout.
Service layer:Is the highest layer of the basic software. This also points out its relevance for the
application software. While access to I/O signals is covered by the ECU Abstraction Layer, the
Services Layer offers:
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Operating system functionality
Vehicle network communication and management services
Memory services (NVRAM management)
Diagnostic services
ECU state management
It provides basic services for application and basic software modules.
Runtime Environment (RTE): Is a middleware providing communication services for AUTOSAR
software components (SWS) and applications containing AUTOSAR sensor / actuator parts.
It makes AUTOSAR software components (SWS) independent of mapping to specific ECUs
and enables implementation of AUTOSAR software. It is responsible for communication
between SWC and BSW.
3.2 What is a client-server interface and what is a sender-receiver
interface? Discuss their properties and differences in the context of
AUTOSAR.
Client / Server interaction: A client sends a request to the server. The client always waits for a
response, server processes this request (Service Indication) and sends the requested information
back to the client (Service Response). It can either be synchronous (blocking) or asynchronous
(non-blocking).
The direction of initiation is used to categorize if an AUTOSAR software component is client or
server. This component can be both, depending on realization. The client can be blocked
(synchronous) or non-blocked (asynchronous) after the service request.
Sender / Receiver (Producer / Consumer) interaction:
The producer produces certain data and transmits it into the network. The consumer does not
request it, he only reads the data from the network. So the producer will never get a response and
the sender is not blocked.
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The sender component does not know the identity or number of the receiver(s) to support
transferability and exchange of AUTOSAR software components. The communication infrastructure
is responsible to distribute information.
3.3 Give a brief overview of the AUTOSAR software development process.
Also explain the relationship between the AUTOSAR development process
and the Vmodel.
On system level: 1. Create software architecture 2. Specify hardware topology 3. Specify network topology 4. Specify system and then export to get a system description and a DBC file
On ECU level:
1. Import the system description and the DBC file 2. Configure the basic software 3. Generate RTE + BSW code + Application templates 4. Build + code loading + debug
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The relationship between the AUTOSAR development process and the Vmodel is that in the beginning the architecture has to be specified. And only when the architecture is done the design of the single components can be started. When those components are designed then the coding (code generation) starts. Then according to the Vmodel each step has its own testing. And only when the tests are passed one can say that the design step was successful.
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3.4 What is "relocatability of software components"? Explain the concept
and give an example.
Interfaces inside and between ECUs
AUTOSAR software components are implemented independently from underlying hardware. This
makes is relocatable.
Relocatability of software components means that the software components can be put on another
ECU without impact on the application design. This allows to distribute them to different ECUs
without changing the specification.
Intra- and inter-ECU communication over the Run-Time Environment (RTE) and the Virtual Function
Bus (VFB) enables relocatability of software components.
The VFB is a virtual hardware which offers mapping independent software integration. It provides a
virtual infrastructure that is independent from the underlying infrastructure. It also provides all
services required for virtual interaction between AUTOSAR components.
The RTE provides implementation possibility for virtual tasks. The RTE code can be adjusted to
implement required communication paths.
It can be said that the RTE is the runtime representation of the VFB for a specific task.
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3.5 AUTOSAR software components are relocatable, i.e. they can be put
on another ECU without impact on the application design. Which AUTOSAR
architecture concepts guarantee this relocatability? Explain your answer.
Interfaces inside and between ECUs
AUTOSAR software components are implemented independently from underlying hardware. This
makes is relocatable.
Relocatability of software components means that the software components can be put on another
ECU without impact on the application design. This allows to distribute them to different ECUs
without changing the specification.
Intra- and inter-ECU communication over the Run-Time Environment (RTE) and the Virtual Function
Bus (VFB) enables relocatability of software components.
The VFB is a virtual hardware which offers mapping independent software integration. It provides a
virtual infrastructure that is independent from the underlying infrastructure. It also provides all
services required for virtual interaction between AUTOSAR components.
The RTE provides implementation possibility for virtual tasks. The RTE code can be adjusted to
implement required communication paths.
It can be said that the RTE is the runtime representation of the VFB for a specific task.
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3.6 What is the difference between an OSEK basic task and an OSEK
extended task? Make a drawing and explain.
A task is a unit of work to be executed. It is necessary that the task has finished before an imposed
dead line → real time requirement!
If there are multiple tasks which occur at the same time they have to be scheduled. Therefore a
priority based scheduler with pre-emption is used very often in RTOS.
Priority based: Each task gets a priority (by configuration). Higher priority task will be scheduled
first.
Pre-emption: A task may be interrupted by a higher priority task.
OSEK is the reference RTOS for automotive embedded systems. AUTOSAR is a standardized
extension of OSEK.
Basic task
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Extended task
The difference between the two types is the availability of an additional state in the extended task in
which the task may be in waiting state. An extra state implies a separate stack for each extended
task while the basic task can share the same stack (depends on RTOS implementation).
Basic stack:
Share stack → saves stack respectively RAM
Can never block
May have several activations
Can lock resources
Cannot wait for an event but reacts on event
Can only finish or be preempted by a higher priority task or IRQ
Saves stack
Extended stack:
Needs an additional stack respectively has their own stack
Has only one activation
Has an infinite loop as body over a WaitEvent() primitive
Can wait for a certain event respectively can use events for synchronization
3.7 What is 'pre-emption of a task'? Explain and give an example.
If there are multiple tasks which occur at the same time they have to be scheduled. Therefore a
priority based scheduler with pre-emption is used very often in RTOS.
Priority based: Each task gets a priority (by configuration). Higher priority task will be scheduled
first.
Pre-emption: A task may be interrupted by a higher priority task.
Example in automotive electronic:
Cruise control is activated – it is tried to keep a certain constant speed
Distance sensor recognizes a too small gap to the car driving ahead
Automatic brake support has higher priority than cruise control
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Cruise control gets terminated immediately
Automatic brake support gets activated immediately
3.8 What is the VFB, and what is the RTE? Describe them briefly, and
discuss their analogies and differences.
Both offer location transparent interaction: Intra- and inter-ECU communication over the Run-Time
Environment (RTE) and the Virtual Function Bus (VFB) enables relocatability of software
components.
Virtual Function Bus (VFB)
System modeling and communication concept.
It is not aware of the location of the Software Components (SWC) on the Electronic Control
Unit (ECU).
It is virtual, this means that it only exists in tools.
It connects port syntax and semantics.
Provides a virtual infrastructure that is independent from the underlying infrastructure→ It
separates application development / modeling from the ECU’s infrastructure
Provides all services which are required for virtual interaction between AUTOSAR
components (underlying hardware)
Run time environment (RTE)
Layer between application layer and basic software
RTE is real
It is generated from VFB and system information
It is aware about intra-ECU and inter-ECU communication – Therefore it makes use of
communication services and OS (system services) → RTE composes runnables to tasks
Provides implementation possibility for virtual tasks
Responsible for communication between application software (SWC) and basic software
(BSW)→ Middleware providing communication services for AUTOSAR software
components (SWS) and applications containing AUTOSAR sensor / actuator parts.
The RTE code can be adjusted to implement required communication paths.
It makes AUTOSAR software components (SWS) independent of mapping to specific
ECUs.
It can be said that the RTE is the runtime representation of the VFB for a specific task.
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3.9 What is a "runnable"? What kinds of runnables do you know? Explain
them.
„Runnables“ are a sequence of instructions that can started by the RTE.
The description of the runnable is in the VFB – it sees the ports of the runnables and the
invocation method
RTE composes runnables to tasks
The operating system does not know about runnables
Type 1:
Terminate within a certain time
Map to basic operating system tasks
Type 2:
Contain one or more wait states
Map to extended operating system tasks (including waiting state)
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3.10 What AUTOSAR mechanism converts runnables into a tasks? Discuss
the possible technical options.
RTE composes runnables to tasks!
RTE event types to invoke a runnable
Activation: Upon appearance of the corresponding RTE event (as specified by the
runnable), the RTE triggers the execution of the runnable
Wake up: For runnables of type 2. Realized by blocking methods in the RTE.
RTE - Implementation
RTE links runnables together to compose a task
RTE possibly generates additional buffers (shadow buffers for IRead & IWrite)
Possible consistency mechanism may be added (mutexes or IRQ-blocking)
Technical options:
Single Type 1 runnable is mapped to one OS task
Two type 1 runnables are mapped to one task (sequential execution of two runnables)
Multiple Type 1 runnables in one extended OS task (task runs in endless loop and RTE
event checks which runnable will be executed)
Single Type 2 runnable to one extended OS task (execution time is not known because of
wait-state, only one can be mapped because it might never stop)
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3.11 Which kinds of messages are defined in OSEK (and therefore also in
AUTOSAR)? And how do they match to properties of message queues?
Explain.
Queued vs. unqueued messages
Unqueued:
The receive buffer can only contain 1 message
The message is not delete after it is read
Queued:
Multiple messages can be stored (FIFO)
Message is deleted after it is read
Event vs. state messages
Event:
E.g. switch on / off, request, fault report…
By nature it is sent only once
The loss of a single event is critical
State:
E.g. actual temperature, RPM…
May be sent multiple times (e.g. regular updates)
The loss of a single message is less critical
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3.12 E.Platform-independent software is less platform-independent as one
might expect. Give two examples that prove this statement in the context of
automotive embedded software.
The hardware is still entangled in application development. AUTOSAR solves this only on the
functional level.
The limits of the used hardware will influence respectively also limit the design of
application software
The choice of sensor has to be taken into account for software design
ABS controller: Discretization and counting of pulses
The value from a sensor can only be processed in software in a way that it does not exceed
the limits (resolution, mechanical properties,…) of the actually used sensor