Salted fish ZTMR example-ultrasonic ranging

Main control board: ZTMR1.1python development board

Ultrasound module

The working principle of the ultrasonic module
(1) uses the IO port TRIG to trigger the distance measurement, and gives a high level signal of at least 10us.
(2) The module automatically sends eight 40khz square waves and automatically detects whether a signal returns.
(3) When a signal returns, a high level is output through the IO port ECHO. The duration of the high level is the time from the transmission of the ultrasonic wave to the return. Test distance = (high level time * speed of sound (340M / S)) / 2.
VCC provides 5V power supply, GND is ground wire, TRIG trigger control signal input, ECHO echo signal output and other four interface terminals.

Pin description

Pin	Explanation
VCC	5v
Trig	Output
Echo	Input
GND	GND

# main.py -- put your code here!
import pyb
from pyb import Pin
from time import sleep_us,ticks_us

trig = Pin('A8',Pin.OUT_PP)
echo = Pin('A7',Pin.IN)
distance = 0
while True:	
	trig.value(1)
	sleep_us(20)
	trig.value(0)
	while echo.value == 0:
		trig.value(1)
		sleep_us(20)
		trig.value(0)
	if echo.value() == 1:
		ts = ticks_us()                 #开始时间
		while echo.value()==1:          #等待脉冲高电平结束
			pass
		te = ticks_us()         
		tc = te-ts				         #结束时间
		distance = (tc*170)/10000        #us(微秒) 1微秒等于一百万分之一秒(10的负6次方秒)
		print('distance',distance,'cm')  #距离计算 （单位为:cm）
	pyb.udelay(20)

Serial tool to see the effect