Analogue versus digital input and output signals
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. A light switch is either ON or OFF. What type of input signal is this?
2. A temperature sensor outputs a voltage that rises smoothly as a room warms up. What type of signal is this?
3. A microprocessor can only work with 1s and 0s. What must a system add to use a smoothly varying sensor signal?
4. Which signal needs no conversion before it reaches a microprocessor?
5. A phone stores a song as digital data. Which converter lets the speaker play it as smooth sound waves?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 1temp = 23.7 | Adac.write(sound_level) | |
| 2button_pressed = 1 | BA switch is a digital input, so it can only be 0 or 1. A value like 0.63 suggests a smooth analogue range. | |
| 3An analogue sensor's smooth signal must be converted to a digital number before the microprocessor can use it | CAn analogue-style reading: a temperature can take any value in a smooth range, not just fixed steps | |
| 4A digital output can be turned into a smooth analogue signal for a speaker using a DAC | DAn analogue light sensor gives a range of values, not just 1 or 0. Showing only on/off treats it as a digital signal. | |
| 5switch_state = 0.63 | EA digital signal: it has only two fixed values, 1 (on) or 0 (off) | |
| 6light_level = 1 # analogue sensor | Fvalue = adc.read() |
C
Definitions
analogue vs digital
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
state = ____________(switch)
if state == 1:
light_on()
2.
level = _____________(temp_sensor)
print(level)
3.
adc = ___(Pin(34))
value = adc.read()
4.
speaker = ___(Pin(25))
speaker.write(volume)
5.
pressed = switch.value()
if pressed == _:
light.on()
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
button = read_pin(2)
B
if button == 1:
C
print("analogue: pressed")
Question 2
A
# temperature sensor is analogue
B
raw = read_digital(0)
C
temp = raw * 0.1
Question 3
A
# sensor voltage to number
B
volts = 2.7
C
number = dac(volts)
Question 4
A
switch = read_adc(4)
B
if switch == 1:
C
motor_on()
Question 5
A
digital_values = [0, 0.7, 1, 0.3]
B
for v in digital_values:
C
set_pin(7, v)
Answer Key
Analogue versus digital input and output signals
Section A: Quick Questions
Q1
B — Digital: it has only two fixed values
Q2
A — Analogue
Q3
B — An analogue-to-digital converter (ADC)
Q4
A — A push-button press (on/off)
Q5
A — Digital-to-analogue converter (DAC)
Section B: Match the Pairs
Q1
temp = 23.7 → An analogue-style reading: a temperature can take any value in a smooth range, not just fixed steps
Q2
button_pressed = 1 → A digital signal: it has only two fixed values, 1 (on) or 0 (off)
Q3
An analogue sensor's smooth signal must be converted to a digital number before the microprocessor can use it → value = adc.read()
Q4
A digital output can be turned into a smooth analogue signal for a speaker using a DAC → dac.write(sound_level)
Q5
switch_state = 0.63 → A switch is a digital input, so it can only be 0 or 1. A value like 0.63 suggests a smooth analogue range.
Q6
light_level = 1 # analogue sensor → An analogue light sensor gives a range of values, not just 1 or 0. Showing only on/off treats it as a digital signal.
Section C: Definitions
Q1
analogue vs digital — Analogue signals vary smoothly over a range; digital signals have fixed values like on/off (1/0). Systems convert between them, e.g. ADC at a sensor input, DAC at a speaker output.Section D: Fill in the Blanks
Q1
state = read_digital(switch)
if state == 1:
light_on()Q2
level = read_analogue(temp_sensor)
print(level)Q3
adc = ADC(Pin(34))
value = adc.read()Q4
speaker = DAC(Pin(25))
speaker.write(volume)Q5
pressed = switch.value()
if pressed == 1:
light.on()Section E: Spot the Error
Q1
C — A button is a switch with only two states, pressed or not pressed (1 or 0), so it is a digital input. The message should say digital, not analogue.
Q2
B — A temperature sensor gives a smoothly varying analogue signal, so it must be read through an ADC with read_adc(). A digital read would only return 0 or 1 and lose the detail.
Q3
C — An analogue sensor voltage has to be turned into a digital number so the microprocessor can use it. That is the job of an ADC. A DAC goes the other way, from digital to analogue.
Q4
A — A switch is a digital input with fixed on/off values, so it should be read with a digital read such as read_pin(). It does not need an ADC, which is for analogue signals.
Q5
A — A digital signal only has fixed discrete values such as 0 and 1. Values like 0.7 and 0.3 vary smoothly and belong to an analogue signal. The list should be [0, 1, 1, 0].