diagram.json

# Wokwi Library List
# See https://docs.wokwi.com/guides/libraries

# Automatically added based on includes:
LiquidCrystal I2C

DHT sensor library for ESPx


libraries.txt

from machine import Pin, time_pulse_us
from utime import sleep_us

__version__ = '0.2.1'
__author__ = 'Roberto Sánchez'
__license__ = "Apache License 2.0. https://www.apache.org/licenses/LICENSE-2.0"

class HCSR04:
    """
    Driver to use the untrasonic sensor HC-SR04.
    The sensor range is between 2cm and 4m.

    The timeouts received listening to echo pin are converted to OSError('Out of range')

    """
    # echo_timeout_us is based in chip range limit (400cm)
    def __init__(self, trigger_pin, echo_pin, echo_timeout_us=500*2*30):
        """
        trigger_pin: Output pin to send pulses
        echo_pin: Readonly pin to measure the distance. The pin should be protected with 1k resistor
        echo_timeout_us: Timeout in microseconds to listen to echo pin. 
        By default is based in sensor limit range (4m)
        """
        self.echo_timeout_us = echo_timeout_us
        # Init trigger pin (out)
        self.trigger = Pin(trigger_pin, mode=Pin.OUT, pull=None)
        self.trigger.value(0)

        # Init echo pin (in)
        self.echo = Pin(echo_pin, mode=Pin.IN, pull=None)

    def _send_pulse_and_wait(self):
        """
        Send the pulse to trigger and listen on echo pin.
        We use the method `machine.time_pulse_us()` to get the microseconds until the echo is received.
        """
        self.trigger.value(0) # Stabilize the sensor
        sleep_us(5)
        self.trigger.value(1)
        # Send a 10us pulse.
        sleep_us(10)
        self.trigger.value(0)
        try:
            pulse_time = time_pulse_us(self.echo, 1, self.echo_timeout_us)
            # time_pulse_us returns -2 if there was timeout waiting for condition; and -1 if there was timeout during the main measurement. It DOES NOT raise an exception
            # ...as of MicroPython 1.17: http://docs.micropython.org/en/v1.17/library/machine.html#machine.time_pulse_us
            if pulse_time < 0:
                MAX_RANGE_IN_CM = const(500) # it's really ~400 but I've read people say they see it working up to ~460
                pulse_time = int(MAX_RANGE_IN_CM * 29.1) # 1cm each 29.1us
            return pulse_time
        except OSError as ex:
            if ex.args[0] == 110: # 110 = ETIMEDOUT
                raise OSError('Out of range')
            raise ex

    def distance_mm(self):
        """
        Get the distance in milimeters without floating point operations.
        """
        pulse_time = self._send_pulse_and_wait()

        # To calculate the distance we get the pulse_time and divide it by 2 
        # (the pulse walk the distance twice) and by 29.1 becasue
        # the sound speed on air (343.2 m/s), that It's equivalent to
        # 0.34320 mm/us that is 1mm each 2.91us
        # pulse_time // 2 // 2.91 -> pulse_time // 5.82 -> pulse_time * 100 // 582 
        mm = pulse_time * 100 // 582
        return mm

    def distance_cm(self):
        """
        Get the distance in centimeters with floating point operations.
        It returns a float
        """
        pulse_time = self._send_pulse_and_wait()

        # To calculate the distance we get the pulse_time and divide it by 2 
        # (the pulse walk the distance twice) and by 29.1 becasue
        # the sound speed on air (343.2 m/s), that It's equivalent to
        # 0.034320 cm/us that is 1cm each 29.1us
        cms = (pulse_time / 2) / 29.1
        return cms

hcsr04.py

from machine import Pin, SoftI2C
from time import sleep
from ssd1306 import SSD1306_I2C
from dht import DHT22
from hcsr04 import HCSR04

I2C_ADDR = 0x3c
totalRows = 4
totalColumns = 20
sensor_dht_pin = 21
sensor_hcsr04_trigger_pin = 18
sensor_hcsr04_echo_pin = 19

i2c = SoftI2C(scl=Pin(17), sda=Pin(16))
lcd = SSD1306_I2C(totalColumns, totalRows, i2c, addr=I2C_ADDR)
sensor_dht = DHT22(Pin(sensor_dht_pin))
sensor_hcsr04 = HCSR04(trigger_pin=Pin(sensor_hcsr04_trigger_pin), echo_pin=Pin(sensor_hcsr04_echo_pin))

def get_temp():
    try:
        sensor_dht.measure()
        temp = sensor_dht.temperature()
        hum = sensor_dht.humidity()
        temp_f = temp * (9/5) + 32.0
        return temp, hum, temp_f
    except OSError as e:
        print('Failed to read DHT sensor.')
        return None, None, None

def get_distance():
    try:
        distance = sensor_hcsr04.distance_cm()
        return distance
    except OSError as e:
        print('Failed to read HC-SR04 sensor.')
        return None

def update_display():
    temp, hum, temp_f = get_temp()
    distance = get_distance()
    if temp is not None and distance is not None:
        lcd.fill(0)
        lcd.text("Temperature: %.1f C" % temp, 0, 0)
        lcd.text("Humidity: %.1f %%" % hum, 0, 1)
        lcd.text("Distance: %.2f cm" % distance, 0, 2)
        lcd.show()

while True:
    update_display()
    sleep(2)


main.py

# MicroPython SSD1306 OLED driver, I2C and SPI interfaces

from micropython import const
import framebuf


# register definitions
SET_CONTRAST = const(0x81)
SET_ENTIRE_ON = const(0xA4)
SET_NORM_INV = const(0xA6)
SET_DISP = const(0xAE)
SET_MEM_ADDR = const(0x20)
SET_COL_ADDR = const(0x21)
SET_PAGE_ADDR = const(0x22)
SET_DISP_START_LINE = const(0x40)
SET_SEG_REMAP = const(0xA0)
SET_MUX_RATIO = const(0xA8)
SET_COM_OUT_DIR = const(0xC0)
SET_DISP_OFFSET = const(0xD3)
SET_COM_PIN_CFG = const(0xDA)
SET_DISP_CLK_DIV = const(0xD5)
SET_PRECHARGE = const(0xD9)
SET_VCOM_DESEL = const(0xDB)
SET_CHARGE_PUMP = const(0x8D)

# Subclassing FrameBuffer provides support for graphics primitives
# http://docs.micropython.org/en/latest/pyboard/library/framebuf.html
class SSD1306(framebuf.FrameBuffer):
    def __init__(self, width, height, external_vcc):
        self.width = width
        self.height = height
        self.external_vcc = external_vcc
        self.pages = self.height // 8
        self.buffer = bytearray(self.pages * self.width)
        super().__init__(self.buffer, self.width, self.height, framebuf.MONO_VLSB)
        self.init_display()

    def init_display(self):
        for cmd in (
            SET_DISP | 0x00,  # off
            # address setting
            SET_MEM_ADDR,
            0x00,  # horizontal
            # resolution and layout
            SET_DISP_START_LINE | 0x00,
            SET_SEG_REMAP | 0x01,  # column addr 127 mapped to SEG0
            SET_MUX_RATIO,
            self.height - 1,
            SET_COM_OUT_DIR | 0x08,  # scan from COM[N] to COM0
            SET_DISP_OFFSET,
            0x00,
            SET_COM_PIN_CFG,
            0x02 if self.width > 2 * self.height else 0x12,
            # timing and driving scheme
            SET_DISP_CLK_DIV,
            0x80,
            SET_PRECHARGE,
            0x22 if self.external_vcc else 0xF1,
            SET_VCOM_DESEL,
            0x30,  # 0.83*Vcc
            # display
            SET_CONTRAST,
            0xFF,  # maximum
            SET_ENTIRE_ON,  # output follows RAM contents
            SET_NORM_INV,  # not inverted
            # charge pump
            SET_CHARGE_PUMP,
            0x10 if self.external_vcc else 0x14,
            SET_DISP | 0x01,
        ):  # on
            self.write_cmd(cmd)
        self.fill(0)
        self.show()

    def poweroff(self):
        self.write_cmd(SET_DISP | 0x00)

    def poweron(self):
        self.write_cmd(SET_DISP | 0x01)

    def contrast(self, contrast):
        self.write_cmd(SET_CONTRAST)
        self.write_cmd(contrast)

    def invert(self, invert):
        self.write_cmd(SET_NORM_INV | (invert & 1))

    def show(self):
        x0 = 0
        x1 = self.width - 1
        if self.width == 64:
            # displays with width of 64 pixels are shifted by 32
            x0 += 32
            x1 += 32
        self.write_cmd(SET_COL_ADDR)
        self.write_cmd(x0)
        self.write_cmd(x1)
        self.write_cmd(SET_PAGE_ADDR)
        self.write_cmd(0)
        self.write_cmd(self.pages - 1)
        self.write_data(self.buffer)


class SSD1306_I2C(SSD1306):
    def __init__(self, width, height, i2c, addr=0x3C, external_vcc=False):
        self.i2c = i2c
        self.addr = addr
        self.temp = bytearray(2)
        self.write_list = [b"\x40", None]  # Co=0, D/C#=1
        super().__init__(width, height, external_vcc)

    def write_cmd(self, cmd):
        self.temp[0] = 0x80  # Co=1, D/C#=0
        self.temp[1] = cmd
        self.i2c.writeto(self.addr, self.temp)

    def write_data(self, buf):
        self.write_list[1] = buf
        self.i2c.writevto(self.addr, self.write_list)


class SSD1306_SPI(SSD1306):
    def __init__(self, width, height, spi, dc, res, cs, external_vcc=False):
        self.rate = 10 * 1024 * 1024
        dc.init(dc.OUT, value=0)
        res.init(res.OUT, value=0)
        cs.init(cs.OUT, value=1)
        self.spi = spi
        self.dc = dc
        self.res = res
        self.cs = cs
        import time

        self.res(1)
        time.sleep_ms(1)
        self.res(0)
        time.sleep_ms(10)
        self.res(1)
        super().__init__(width, height, external_vcc)

    def write_cmd(self, cmd):
        self.spi.init(baudrate=self.rate, polarity=0, phase=0)
        self.cs(1)
        self.dc(0)
        self.cs(0)
        self.spi.write(bytearray([cmd]))
        self.cs(1)

    def write_data(self, buf):
        self.spi.init(baudrate=self.rate, polarity=0, phase=0)
        self.cs(1)
        self.dc(1)
        self.cs(0)
        self.spi.write(buf)
        self.cs(1)