L3 - Embedded Hardware Flashcards
What do we understand under a synchronous interrupt? Name an example.
Occur at the same time. E.g.: Exception, Segmentation Fault or Division by zero.
Name five characteristics of a microcontroller.
- many interrupts
- high I/O functionality
- low level processing
- interfacing with sensor/actuators
- low cost
What are characteristics of FPGA?
FPGA have reprogrammable hardware (VHDL, Verilog) and are very fast in execution of logic operations.
What are FPGA?
FPGA (Field Programmable Arrays) are a combination of standard hardware (e.g. DSP) and fully application specific hardware (e.g. ASIC).
What are characteristics of a Heap?
- Memory allocation dynamically (memory size does not have to be known @compile time)
- must be managed (allocation & deallocation)
Which companies do produce microprocessors?
Intel, AMD and ARM.
Name on advantage and disadvantage of interrupts.
- PRO: resources only used when needed
- CON: execution is interrupted in non-deterministic manner
A Gyroscope…
A Gyroscope measures angular velocity around an axis and is often combined with an accelerometer for an inertial measurement unit (IMU)
Is a microcontroller faster than a microprocessor?
Compared to a microprocessor, a microcontroler is relatively slow but does not need many external parts, has a low energy consumption and a low cost.
What is an ADC and what is its task?
An ADC (Analog Digital Converter) circuit maintains input during conversion time. To cut off the higher frequencies before sampling, an antialiasing filter is necessary and prevents higher frequency noise from disturbing low frequency signals.
An embedded system should be ______________.
reliable
What are the tasks of a DSP?
A DSP is optimized for signal processing such as:
- filtering
- system identification
- frequency analysis
- machine learning
- feature extraction
H-Bridges are used …
H-Bridges are used to drive large loads and switches driven by PWM (magn. coils, motors)
In which kind of applications are Embedded Systems used? Name two.
- simple control tasks in household appliances
- entertainment electronics
- communication systems
- automotive applications
- control of complex automation systems in industrial environments
What are interrupts?
normal execution is automatically interrupted when environment changes
Name on advantage and disadvantage of polling.
- PRO: short latencies (low number of IOs), events do not block execution of the program
- CON: unnecessary polls, high CPU usage, reaction dime depends on number of IOs
What is polling?
continuously poll I/Os for a change
Reduced instruction set RISC (ARM)
- simple machine instructions
- used in embedded systems (real-time hardware)
What is a Cache?
A cache is a very fast memory that stores data which is often accessed. While making timing issues difficult to analyse, it improves drastically execution and access times.
What is the name of a memory segment in RAM that is organised as LIFO?
Stack.
What is a key requirement for embedded processors? What mechanisms are not acceptable?
In RTS deterministic behaviour is essential to guarantee high accuracy. Non-deterministic mechanisms (e.g. Virtual Memory, Garbage Collection, Asynchronous IO requests, Recursive function calls) are unwanted.
What is an ASIC?
An ASIC (Application Specific Integrated Circuit) are tasks that are implemented in hardware design and therefore feasible for large quantities. Their functionality cannot be changed.
If an interrupt is caused by an external event, it is called _______________ interrupt. Name an example.
asynchronous. E.g.: timer overrun, end of I/O operation or external pin voltage.
Which sensor does measure the acceleration, sense vibrations and is used for navigation?
Accelerometer.
A Digital Analog Converter (DAC) …
A DAC converts digital input code (binary) to an analog output voltage.
How can a system react to environmental changes?
Polling & Interrupting
What are the main steps when executing a task?
- Fetch instruction
- Decode
- Execute on the ALU
- Memory Access (L/S)
- Write back into register
Complex instruction set CISC (x86)
- maps complexity of common instructions directly in machine code
- timing issues used in general purpose computing
Pulse Width Modulation (PWM) delivers …
PWM delivers variable amounts of power to external hardware and is programmable through PWM interface of timer Pulse.
What does ALU stand for?
Arithmetic Logic Unit.
What is a DSP?
A DSP (Digital Signal Processor) is a high performance ALU (parallelization) and control unit.
Encoder
relative position obtained by counting ticks via digital magneto or optical resistant (used in robotics and motor control)
Overlapping execution of different tasks can lead to conflicts. Name three different conflicts that can occur.
- resource hazard
- data hazard
- control hazard
Name the actuator that reads a bit in a register and sets a voltage of a pin to high or low.
General Purpose IO (GPIO)
