Embedded systems exam 2

What is a resolver?

Works off the same principle as a transformer with a primary and a secondary winding

An interrupt is ______________ in order to stop calling the function for the event.

disabled

when a specific type of event has been configured to accept an interrupt, it is referred to as

enabled

What is an optical encoder?

has an LED and light detector on a slotted plate. represents speed of rotation

the function that is called when a specific event occurs is referred to as an

interrupt handler or more commonly an interrupt service routine (ISR).

The portion of reserved memory that contains the addresses of the interrupt service routines is called

interrupt vector table or an interrupt jump table.

What is an automated hardware mechanism?

interrupts

Problem with delay() is that

it stalls code making it so nothing else can happen until its done

What are three types of analog - to - digital converters (ADC)

Flash (fastest, expensive) Dual Slope(Averaged) Sigma Delta (slow)

What is difference between Stepper motors and BLDC motors?

Magnetism of rotor is longitudinal instead of perpendicular to axis of rotation

In gray code, add a 0 to the MSB and adjacent bits that are different generate a

1

Audio CD's sample at

44100hz

POTS (old phone service)

8000 hz common speech quality

In stepper motors and BLDC motors, how is torque improved?

coils are split in order to create opposing poles?

What is timbre?

combination of frequencies to make a sounds

In a DC motor, electric current is supplied externally through a ________

commutator

What are servos?

DC motors with some simple logic uses PWM signal running 25-50hz pulses are between .5-2.5 ms pulse of 1.5ms centers servo 180-360' limited rotation

In DC motors, speed is proportional to

DC voltage -direction can be changed by swapping DC voltage polarity - Pulse Width Modulation

What are benefits of using Brushless DC motors?

Improve precision. control direction, and improve torque using multiple poles

What does increasing the bit depth do?

Increase storage requirements increases the maximum dynamic range more bit depth = smoother sound

What is problem with analog recording?

Noise is easily added with each copy attenuation of signal over time

What is a bit depth?

Number of bits used to represent each sample

What difference between falling and rising button push?

RISING - ISR is called when the pin goes from low to high. FALLING - ISR is called when the pin goes from high to low.

On digital audio quality, what are the two factors?

Sampling rate sample bit depth

What is a digital position sensor?

Switch like sensors can be positioned around a disk which can then be mounted to a shaft -input to processor is similar to switch inputs

Timer_A is a 16-bit timer/counter

True

In Brushless DC (BLDC) Motors, how does it control position of magnet??

Using a coil

Why use gray code?

When multiple bits change simultaneously, there is always a chance that a misread by the processor can occur Only one bit changes when going through the sequence

how to write to servo

myServo.writeMicroseconds(x)

What is polling?

read value from timer, add 'one' second, then watch timer until it reaches this value

What is sample rate?

sample rate is the number of samples captured per second. Measured in hertz, samples per second

How to determine size of audio file?

sample x bit depth x number of channels x how many minutes x60 seconds

What is Nyquist Frequency?

sampling rate must be twice as fast as highest frequency you wish to capture higher frequencies must be removed before sampling to prevent aliasing

Steps to setting up timer

select clock source select an input divider setting the timer mode (count up to all ones and start over) - continuous mode Clear the timer interrupts - polling

Analog recordings reprsent

the shape of the waveform directly

When electric current passes through a coil in a magnetic field, the magenetic force produces a ___________ which turns the DC motor

torque

Low bit-depth will result in hiss or added noise

true

The Nyquist Frequency says the sampling rate must be twice as fast as highest frequency you wish to capture

true

Digital "samples" the waveform at evenly spaced timepoints

true each sample/number is stored Benefits: no degradation over time compression can be applied

True or false: in Stepper motors, changing polarity of opposite coil creates "step" in either clockwise or counter-clockwise direction

true it is also possible to perform "half steps" by energizing both coils

Clipping is when anytime sound goes beyond maximum levels of ADC

true, result is distortion

What function do you use to attach an interrupt?

void attachInterrupt(interrupt, function, mode)