Problem with Lopy4 and MaxBotix Ultrasonic sensor

[jlproyectos]

Hi

I have a problem and have been trying to solve it for 1 week. I have a MaxBotix MB7052 ultrasound sensor and I want to get the readings with a Pycom Lopy4.

https://www.maxbotix.com/documents/XL-MaxSonar-WR_Datasheet.pdf

I have used it before with an ESP8266 and ESP32 development board, but now I want to use Lopy4.
I use the following code in the ESP:

data = pulseIn(pwPin1, HIGH);
cm = data/58;

Where pwPin1 is:
const int pwPin1 = 2;

With Lopy 4 I have tried with Analogic, Pulse-Width and UART, but none of the ways I can get the right information

Is there a function equivalent to Arduino's PulseIn? What could I be doing wrong?

Try with:
pulses_get https://docs.pycom.io/firmwareapi/pycom/pycom/
https://forum.pycom.io/topic/5737/maxbotix-ultrasonic-sensor-gpy/2
https://docs.pycom.io/firmwareapi/pycom/machine/uart/

[ric2498]

Hi,

With this code found online and adapted for my ultrasonic range finder sensor I can read the distance on my sensor .... If it can help.... for sure you will have to modify it according to the PINs used by the MaxSonar... you should be able to read the data on the pin 2 provided by Maxsonar.

Pin 2-This pin outputs a pulse-width representation of range. To calculate the distance, use a scale factor of 58uS per cm. (MB7051, MB7052, MB7053, MB7060, MB7062, MB7066, MB7067, MB7068)This pin outputs the analog voltage envelope of the acoustic waveform. For the MB7070 series and MB7092 sensors, this is a real-time always-active output (MB7070, MB7072, MB7076, MB7077, MB7078, MB7092)

Here's the code extracted from my project (it may need mods...)

import pycom
import time, utime
from machine import Pin
from machine import Timer
import binascii

# create an output pin on pin #12
p12 = Pin('P12', Pin.OUT)
chrono = Timer.Chrono()

#def ReadDistance(pinRM):
def ReadDistance():
    p12.mode(p12.OUT)
    p12.value(0) #low
    utime.sleep_ms(2)
    p12.value(1) #high
    utime.sleep_ms(5)
    p12.value(0) #low
    p12.mode(p12.IN)

    duration = 0
    chrono.reset()

    while p12() == 0:
        pass

    chrono.start()

    while p12() == 1:
        pass

    chrono.stop()

    duration = chrono.read_us()
    print("Duration = ",duration)

    return duration

while True:
    distancerm = 0
    distancerm = ReadDistance()
    pouces = distancerm/74/2
    print('%3.1f = formatted rounded float\n' % round(pouces, 1))
    pouces = int(pouces)
    cm = distancerm/29/2
    cm = int(cm)
    print("Distance de l'objet est = ",cm," cm ou ",pouces," pouces")
    time.sleep(5)

Good luck.

Richard.

[jlproyectos]

@ric2498 said in Problem with Lopy4 and MaxBotix Ultrasonic sensor:

Hi,

With this code found online and adapted for my ultrasonic range finder sensor I can read the distance on my sensor .... If it can help.... for sure you will have to modify it according to the PINs used by the MaxSonar... you should be able to read the data on the pin 2 provided by Maxsonar.

Pin 2-This pin outputs a pulse-width representation of range. To calculate the distance, use a scale factor of 58uS per cm. (MB7051, MB7052, MB7053, MB7060, MB7062, MB7066, MB7067, MB7068)This pin outputs the analog voltage envelope of the acoustic waveform. For the MB7070 series and MB7092 sensors, this is a real-time always-active output (MB7070, MB7072, MB7076, MB7077, MB7078, MB7092)

Here's the code extracted from my project (it may need mods...)

import pycom
import time, utime
from machine import Pin
from machine import Timer
import binascii

# create an output pin on pin #12
p12 = Pin('P12', Pin.OUT)
chrono = Timer.Chrono()

#def ReadDistance(pinRM):
def ReadDistance():
    p12.mode(p12.OUT)
    p12.value(0) #low
    utime.sleep_ms(2)
    p12.value(1) #high
    utime.sleep_ms(5)
    p12.value(0) #low
    p12.mode(p12.IN)

    duration = 0
    chrono.reset()

    while p12() == 0:
        pass

    chrono.start()

    while p12() == 1:
        pass

    chrono.stop()

    duration = chrono.read_us()
    print("Duration = ",duration)

    return duration

while True:
    distancerm = 0
    distancerm = ReadDistance()
    pouces = distancerm/74/2
    print('%3.1f = formatted rounded float\n' % round(pouces, 1))
    pouces = int(pouces)
    cm = distancerm/29/2
    cm = int(cm)
    print("Distance de l'objet est = ",cm," cm ou ",pouces," pouces")
    time.sleep(5)

Good luck.

Richard.

Thanks Richard for the response. Its code works correctly, although sometimes there is an error in the measurements.

at distances of 114 cm it sometimes indicates 120, 140 or even 201!

I will try to adjust it so that the values are correct. However, I have questions about your code

Why wait 2 and 5ms? And what do the functions mean?
p12.value(0) #low, #hight and #low again

[ric2498]

@jlproyectos

Hi,

It is the PING trigger to establish the duration of the ping for the Sensor that I used (Ultrasonic Distance Sensor - HC-SR04 (4 pins)), to convert the time into a distance.