IOT Midterm
At what temperature is a coin-cell battery capacitor assisted power source more important?
0C
Order the following pseudo code for a generic non-nested interrupt handler routine: disable all interrupts Interrupt flag variable = source interrupt register clear cause of source interrupt interrupt handling routine re-enable interrupts
1 2 3 4 5
To save energy a bluetooth LE device can reduce its period on to save energy. What is the maximum period that the Bluetooth LE device can be off before a communication time-out occurs?
16 seconds
An accelerometer sensor measures both gravity and linear acceleration. What value will the accelerometer measure while stationary?
1g
How long does it take a Bluetooth LE typically to make a connections?
2-4 milli seconds
How long does it take a bluetooth classic typically to make a connection?
2-4 seconds
Bluetooth Smart used how many channels for advertising?
3
How many data channels does Bluetooth Smart utilize?
37
How long is the longest data packet in Bluetooth low energy?
376uS
Which version of bluetooth introduced ultra-low-power-consumption into the specifications?
4.0
Which version of bluetooth smart introduced forward error correction (FEC) to extend the range of the bluetooth radio?
5
If the maximum count of the LETIMER0 is 65,536, what would the minimum LETIMER0 LFXO prescaler need to be to enable the LETIMER0 to count to 12 seconds based on the LFXO set to the frequency of 32,768 to interrupt on the underflow condition only when 12 seconds have past. What count would be required to be stored in the LETIMER0->CNT register to equal 12 seconds based on the above prescaler which is indicated upon an underflow event?
8 49152
How long is the shortest data packet in Bluetooth Low Energy?
80us
Bluetooth Mesh's backward compatibility with Bluetooth Smart is due to that Bluetooth Mesh is not an integral part of the Bluetooth Smart stack, but rather [answer] to it.
A separate entity or addition to it
Bluetooth Smart devices are geared for applications with the following characteristics. Select all that apply.
Asynchronous communications. Small amounts of data
Select the most appropriate Bluetooth standard to application. (Each answer will be used at least once) Personal fitness tracker: Fitness equipment installed in athletic facilities: Wireless audio: Auditorium lighting:
BLE Bluetooth mesh Bluetooth basic rate/enhanced data rate Bluetooth mesh
Select the most appropriate Bluetooth standard to application. (Each answer will be used at least once) Cable replacement : Powered by coin cell : Enhanced range of network: Connect smart phone to the car infotainment system:
Bluetooth Basic Rate/Enhanced Data Rate Bluetooth low energy Bluetooth mesh Bluetooth Basic Rate/Enhanced Data Rate
A node can read the message if it has the following security keys?
Both the Network and Application Keys
In an Infrared Phase-based gesturing system, if diode 1 is to the left of the sensor, diode 2 is to the right of the sensor, and diode 3 is below the system, what direction is the hand gesturing if the rising in feedback comes in the following order; D3, and then D1 and D2?
Bottom to Top
Mesh networking advantages arise from the use of relaying messages from one point to another via hopping across bidirectional channels instead of <ANSWER> device communicating with individual peripherals devices
Central or Master Node or Star Configuration
Event-driven programs are prone to <ANSWER> bugs due to their inherent nature of handling <ANSWER> events
Concurrency Asynchronous
_________ happen when a shared memory is uncoordinated with at least one write by both an event handler and a non-event code or by multiple event handlers.
Data races
Which type of bluetooth radio would most likely be used in a new client device?
Dual-mode
Write the C-code to remove the Vertical Front Porch Interrupt Enable, VFPORCH, of the External Bus Interface, EBI, peripheral interrupt enable register, IEN.
EBI->IEN &= ~VFPORCH;
Write the C-code to add the Vertical Front Porch Interrupt Enable, VFPORCH, of the External Bus Interface, EBI, peripheral interrupt enable register, IEN.
EBI->IEN |= VFPORCH;
In which energy mode of the blue gecko is the CPU available? (All of the particular peripheral must be available in that energy mode)
EM0
In which Energy Mode of the Blue Gecko are the Asynchronous peripherals available? (All of the particular peripheral must be available in that Energy Mode)
EM0, EM1, EM2, EM3
In which Energy Mode of the Blue Gecko are the High-Frequency peripherals available? (All of the particular peripheral must be available in that Energy Mode)
EM1, EM0
At what energy state does LFXO and LRFCO oscillators are first disabled in the blue gecko?
EM3
Using the Blue Gecko data sheet and reference manual, what would be the lowest sleep mode that the Blue Gecko could enter after enabling the I2C as an I2C slave and detect its I2C slave address after a successful BlockSleepMode()?
EM3
How do multiple Bluetooth Classic Piconets coexist in the same proximity?
Each Piconet is synchronized to a specific frequency hopping pattern
To minimize the possibility of a concurrency bug, which of the following should not be done?
Enable events before accessing shared data
In Simplicity Studio, what hot key will open a symbol's declaration?
F3
Bluetooth LE is targeting the same applications as bluetooth classic, but at a lower energy/power level.
FALSE
Bluetooth smart is an asymmetric architecture where the resource rich devices perform the advertising.
FALSE
A Bluetooth Smart Ready device is the same as a Bluetooth Low Energy radio?
False
An instruction cache always improves the energy efficiency of a micro-controller (true or false).
False
Bluetooth Classic is architected for applications that need to transmit a few bytes of data every second.
False
Bluetooth LE is targeting the same applications as Bluetooth Classic, but at a lower energy/power level.
False
Bluetooth Mesh messages span large physical spaces using increased power radio transceivers?
False
This scheme of mesh networking sends the message from sender to receiver through a mapped path.
False
What are the required PCB placement and layout considerations while designing with a magnetometer? (select all that apply)
Far enough away from current carrying wires so that their induced magnetic fields are below the design target error budget.
Bluetooth uses the specific type of mesh network called [answer].
Flood Network
Which Bluetooth LE term is most similar in functionality to a GATT Client?
GAP Central
Match the term with its definition: Specifies the structure in which profile data is exchanged: Defines basic requirements of a Bluetooth device: Defines packet structure and control:
GATT GAP LINK LAYER
For the Silicon Lab' Si70xx temperature and humidity sensors, the thermal input to the temperature sensor is what?
Ground
For the silicaon lab Si70xx temperature and humidity sensors, the thermal input to the temperature sensor is what?
Ground
The blue gecko I2C peripherals obtain its clock from what source?
HFPERCLK
For which hop value would result in remapping due to WiFi channel 6 interference that corresponds to BLE channels 11-20 if at n=0, f = channel 7 at n = 8?
Hop = 10
For which hop value would result in remapping due to WiFi channel 1 interference that corresponds to BLE channels 0-8 if at n=0, f = channel 3 at n = 8?
Hop = 14
A Bluetooth Mesh message may be relayed multiple times over what are termed as ______
Hops
In Simplicity Studio, _____ over a function or macro in the editor will expand information on that symbol.
Hover
Silicon Labs humidity and temperature sensors have unique applications and use requirements that are not common to other conventional (non-sensor) IC solutions. Select all that apply.
Humidity sensor "memory". Prevent contamination of the sensor through-out its product life cycle The need to protect the sensor during board assembly
<Answer> means that once a service is published, it cannot change.
Immutable
Event-driven systems are alternatively called ________ systems.
Interrupt
Complete the below C line of code to start LETIMER0 by writing directly to its register.
LETIMER0->CMD = LETIMER_CMD_START;
Select all the C lines of code that would just disable the LETIMER0 underflow interrupt.
LETIMER0->IEN &= ~LETIMER_IEN_UF; LETIMER_IntDisable(LETIMER0, LETIMER_IEN_UF);
In an Infrared Phase-based gesturing system, if diode 1 is to the left of the sensor, diode 2 is to the right of the sensor, and diode 3 is below the system, what direction is the hand gesturing if the feedback comes in the following order; D1, D3, and then D2?
Left to Right
In selecting an energy source, mobility, <ANSWER>, cost, and form factor need to be considered
Lifetime
What were the design goals of the original Bluetooth radio? (select all that apply)
Low cost, worldwide operation, short range
A magnetometer alone cannot provide an accurate compass heading for which reason(s)? (select all that apply)
Magnetic field measurements varies significantly with its angle or tilt to the earth. Magnetometer requires calibration to determine its own offset Magnetometer requires calibration from hard-iron effects.
For which Connection Events, n, would the frequency channel need to be remapped due to interference from WiFi's channel 6 which corresponds to BLE's channels 11-20? (select all that apply) Assumptions: at n=0, f(0) = channel 9, hop = 14
N = 3, n = 6
________ are used to allow time-sensitive events to be handled with low latency.
Nesting events/Nested Interrupts/ Preempted interrutps
Relay nodes typically have valid <ANSWER>while the designation node must also have a valid <ANSWER>to access the message
Netkey and AppKey
Select all the advantages to Bluetooth Mesh's networking topology.
No need for a centralized router Enables multiple transmission data paths
If the magnetometer is inverted, what orientation will the X-axis be at its maximum?
North
In an aerospace coordinate system, which direction does the X-axis point?
North
DMA reduces energy in a system by _______ some memory transfers from the CPU.
Offloading
In an infrared based gesturing system using multiple LEDs, the general guideline is to insure there is no "dead spot." Where is this "dead spot" most likely to occur?
Over the middle of the detectable area
In Bluetooth Mesh, the models communicate with each other through a [3wordanswer] system.
Publish and Subscribe
1The Bluetooth 5 2 Mbps PHY can save energy due all the following. Select all that apply.
Radio on for a shorter period of time. Device can be in sleep mode longer
Bluetooth 5 increases <ANSWER> and <ANSWER> compared to bluetooth 4.2 which moves bluetooth smart a step closer to an IoT foundation technology.
Range and Bandwidth
Bluetooth mesh networking enables communication over large areas by allowing nodes to be designated as <ANSWER> nodes.
Relay
In the Bluetooth LE Generic Attribute Profile (GATT), what are the primary roles defined? (select all that apply)
Server & Client
When connections are transient like in bluetooth low energy, the time to make a connection must be <ANSWER>
Short
Match the application to the most appropriate CPU architecture. M4: M3: M0:
Signal Processing Mixed Application Control Logic
What are the valid communication standards between different Bluetooth devices? (select all that apply)
Single-Mode to Single-Mode in Bluetooth LE Dual-Mode to Dual-Mode in Bluetooth LE Classic to Dual-Mode in Bluetooth Classic
To optimize energy savings, the microcontroller should <ANSWER> as deeply, and <ANSWER> as seldom as possible
Sleep/Wake
Bluetooth classic can be in the following network configurations? (Options: star network,mesh network,hybrid mesh/ star network, scatternet)
Star network and scatternet
An event alone can not determine the next action in an event-driven embedded system, but _______ is equally important.
State
Phase-based gesture sensing is based on timing of the changes in signals to determine the direction of an object's motion.
TRUE
Which device is the primary power source in the BLE device while in sleep mode?
The Coin Cell Battery
Which device is the primary power source in a BLE device while the radio is active?
The capacitance
Select all the statements below that incorporate the Bluetooth Low Energy Asymmetric Design Philosophy.
The slave does not run the profile A device with more energy resources are given more to do Master devices perform scanning
In an Infrared Phase-based gesturing system, if diode 1 is to the left of the sensor, diode 2 is to the right of the sensor, and diode 3 is below the system, what direction is the hand gesturing if the rising in feedback comes in the following order; D1 and D2, then D3?
Top to bottom
A Bluetooth Smart Ready device is equivalent to a Bluetooth dual-mode device.
True
Bluetooth Mesh networks can support large number of devices?
True
Relative humidity is the ratio of actual water vapor present in air with the amount of water vapor that would be present in air at saturation.
True
To save energy, Bluetooth LE uses only 3 radio frequencies for discoverability out of the 40 radio channels.
True
Which clock sources can the LETIMER0 in the blue gecko use in EM2
ULFRCO, LFXO, LFRCO
Each element in a Bluetooth Mesh node must have which of the following unique addresses?
Unicast address
Each element in a bluetooth mesh node must have which of the following unique addresses?
Unicast address
For Silicon Labs' temperature and humidity sensors, prolonged exposure to high humidity can cause a gradual drift to the humidity sensor readings. How can this shift due to prolong exposure to humidity be reversed?
Use the integrated heater to heat the die to over 100C for 24 hours
Before Bluetooth Mesh became an option, for home applications that require a Mesh Network, the application developer was limited to which of the following Mesh technologies?
Zigbee, Thread
Asynchronous events can trigger at any time preempting non-event code that can expose shared state variables to concurrency bugs. It is recommended to _______ dangerous events before sensitive operations like accessing global variables.
disable
Match the following: Way to share data between a program and its event handler : Data Races : A considerable amount of its computational is initiated and influenced by external events. :
global variable currency bugs Event-driven
Bluetooth Mesh uses the following scheme for its messages. Select the most appropriate.
managed flooding
Match the security threat with how Bluetooth Mesh protects against it. Replay attacks : Man in the Middle attacks : Trash-can attacks :
message sequence numbers asymmetrical cryptography ability to refresh security keys
Select all the issues that the Bluetooth Mesh was designed to address compared to other low power mesh networks.
not supported by smart phones low transmission data rates limited number of hops
Match the address characteristic to its address type Addressing elements that do not have a unique address : Provisioner allocates a unique address to each element during provisioning : May be subscribed to : Addressing Multiple elements from one or more nodes :
unassigned address unicast address Virtual Address Group Address
