IoT MicroPython

What is the device displayed on the image ?

Please explain what is Trig, Echo, VCC and GND pin.

See carefully there are 'T' (left-bottom side) and 'R' (right-bottom side). Explain them.

trigger = Pin(TRIGGER_PIN, Pin.OUT)

echo = Pin(ECHO_PIN, Pin.IN)

led = Pin(LED_PIN, Pin.OUT)

Please explain the differences between trigger.value(0) and trigger.value(1).
What's 1 and 0 for ?
Why trigger using Pin.OUT and echo is Pin.IN ?

trigger.value(1)

sleep_us(10)

trigger.value(0)

pulse_time = time_pulse_us(echo, 1)

distance = (SPEED * pulse_time) / 2

How long the wave is sent ?
what is the distance unit we got from the formula at the last line ?

buzzer = Pin(SPEAKER_PIN, Pin.OUT)

buz = PWM(buzzer)

What's the following code do ?

buz.freq(1047)

buz.duty(20)

sleep(0.5)

buz.duty(0)

buzzer = Pin(SPEAKER_PIN, Pin.OUT)

buz = PWM(buzzer)

What's .freq( ) function for if we use the command buz.freq(1000) ?

buzzer = Pin(SPEAKER_PIN, Pin.OUT)

buz = PWM(buzzer)

buz.freq(1000)

buz. (a)   (25)

Fill in the blank to change the volume to 50%

count = 0

while (a)   :

led.value(1)

sleep(1)

led.value(0)

sleep(1)

Fill in the blank to make the program blinking for 10 times.

from machine import Pin

from time import sleep

____________________________

while True:

led.value(1)

sleep(1)

led.value(0)

sleep(0)

When we compile the code above, we will got error led isn't defined. Fill in the blank to fix it. Assume the Pin number is 14.