EZ2 SONAR and BBBW

# This Code uses the:
# * Maxbotic LV-EZ2 Ultrasonic Sensor

# Tested with the BBBW
# This sketch reads the LV-EZ2 by pulse count
# Then prints the distance to the python console

# The circuit:
# * 3.3v on the BBBW to LV-EZ2 Pin 7 Vcc
# * GND on BBBW to the LV-EZ2 Pin 6 GND
# * LV-EZ1 Ultrasonic Sensor PW pin to BBBW P9_14
# * LV-EZ2 Sensor PWM usage!

import time
import Adafruit_BBIO.PWM as PWM
#import Adafruit_BBIO.UART as UART
import serial

# ez2pin = "P9_12"
PWM2 = "P9_14"
# UART.setup("UART2")

# GPIO.setup(ez2pin, "GPIO.OUT")
PWM.start(PWM2, 50, 2000, 1)

# calculated mode or median distance
mode_result = 0

# storing multiple pulses
# read in time for pin to transition
samples = 18
pulses = (PWM2, maxlen=samples)

# sensor reads which are in range will be stored here
rangevalue = [0, 0, 0, 0, 0, 0, 0, 0, 0]

# 1s sensor power up pause
time.sleep(1)


def tof_cm(time_of_flight):
    # EZ1 ultrasonic sensor is measuring "time of flight"
    # Converts time of flight into distance in centimeters
    convert_to_cm = 58
    cm = time_of_flight / convert_to_cm

    return cm


def tof_inches(time_of_flight):
    # EZ1 ultrasonic sensor is measuring "time of flight"
    # Converts time of flight into distance in inches
    convert_to_inches = 147
    inches = time_of_flight / convert_to_inches

    return inches


def find_mode(x):
    # find the mode (most common value reported)
    # will return median (center of sorted list)
    # should mode not be found
    n = len(x)

    max_count = 0
    mode = 0
    bimodal = 0
    counter = 0
    index = 0

    while index < (n - 1):
        prev_count = counter
        counter = 0

        while (x[index]) == (x[index + 1]):
            counter += 1
            index += 1

        if (counter > prev_count) and (counter > max_count):
            mode = x[index]
            max_count = counter
            bimodal = 0

        if counter == 0:
            index += 1

        # If the dataset has 2 or more modes.
        if counter == max_count:
            bimodal = 1

        # Return the median if there is no mode.
        if (mode == 0) or (bimodal == 1):
            mode = x[int(n / 2)]

        return mode


while True:

    # wait between samples
    time.sleep(.5)

    if len(pulses) == samples:
        j = 0  # rangevalue array counter

        # only save the values within range
        # range readings take 49mS
        # pulse width is .88mS to 37.5mS
        for i in range(0, samples):
            tof = pulses[i]  # time of flight - PWM HIGH

            if 880 < tof < 37500:
                if j < len(rangevalue):
                    rangevalue[j] = tof_cm(tof)
                    j += 1

        # clear pulse samples
        pulses.clear()  # clear all values in pulses[]

        # sort samples
        rangevalue = sorted(rangevalue)

        # returns mode or median
        mode_result = int(find_mode(rangevalue))

        # python console prints both centimeter and inches distance
        cm2in = .393701
        mode_result_in = mode_result * cm2in
        print(mode_result, "cm", "\t\t", int(mode_result_in), "in")

        # result must be in char/string format for LCD printing
        # digit_string = str(mode_result)

        time.sleep(2)