MicroPython RP2040读取DHT11温湿度传感器数据+ 0.96“I2C oled显示

Posted 2022-09-07 perseverance52

【MicroPython RP2040】读取DHT11温湿度传感器数据+ oled显示

---

• ✨本示例基于Thonny平台开发。
  

📒RP2040开发板

• 📘YD-RP2040开发板
  

🎄DHT11传感器

🎄ssd1306 I2C 0.96寸 OLED屏幕

📌注意事项

⛳在运行代码前，需要先将ssd1306 0.96寸 I2C OLED连接到RP2040开发板对应的引脚上，否则会报错，找不到I2C设备。

📔所需库模块

💎dht.py

import array
import micropython
import utime
from machine import Pin
from micropython import const
 
class InvalidChecksum(Exception):
    pass
 
class InvalidPulseCount(Exception):
    pass
 
MAX_UNCHANGED = const(100)
MIN_INTERVAL_US = const(200000)
HIGH_LEVEL = const(50)
EXPECTED_PULSES = const(84)
 
class DHT11:
    _temperature: float
    _humidity: float
 
    def __init__(self, pin):
        self._pin = pin
        self._last_measure = utime.ticks_us()
        self._temperature = -1
        self._humidity = -1
 
    def measure(self):
        current_ticks = utime.ticks_us()
        if utime.ticks_diff(current_ticks, self._last_measure) < MIN_INTERVAL_US and (
            self._temperature > -1 or self._humidity > -1
        ):
            # Less than a second since last read, which is too soon according
            # to the datasheet
            return
 
        self._send_init_signal()
        pulses = self._capture_pulses()
        buffer = self._convert_pulses_to_buffer(pulses)
        self._verify_checksum(buffer)
 
        self._humidity = buffer[0] + buffer[1] / 10
        self._temperature = buffer[2] + buffer[3] / 10
        self._last_measure = utime.ticks_us()
 
    @property
    def humidity(self):
        self.measure()
        return self._humidity
 
    @property
    def temperature(self):
        self.measure()
        return self._temperature
 
    def _send_init_signal(self):
        self._pin.init(Pin.OUT, Pin.PULL_DOWN)
        self._pin.value(1)
        utime.sleep_ms(50)
        self._pin.value(0)
        utime.sleep_ms(18)
 
    @micropython.native
    def _capture_pulses(self):
        pin = self._pin
        pin.init(Pin.IN, Pin.PULL_UP)
 
        val = 1
        idx = 0
        transitions = bytearray(EXPECTED_PULSES)
        unchanged = 0
        timestamp = utime.ticks_us()
 
        while unchanged < MAX_UNCHANGED:
            if val != pin.value():
                if idx >= EXPECTED_PULSES:
                    raise InvalidPulseCount(
                        "Got more than  pulses".format(EXPECTED_PULSES)
                    )
                now = utime.ticks_us()
                transitions[idx] = now - timestamp
                timestamp = now
                idx += 1
 
                val = 1 - val
                unchanged = 0
            else:
                unchanged += 1
        pin.init(Pin.OUT, Pin.PULL_DOWN)
        if idx != EXPECTED_PULSES:
            raise InvalidPulseCount(
                "Expected  but got  pulses".format(EXPECTED_PULSES, idx)
            )
        return transitions[4:]
 
    def _convert_pulses_to_buffer(self, pulses):
        """Convert a list of 80 pulses into a 5 byte buffer
        The resulting 5 bytes in the buffer will be:
            0: Integral relative humidity data
            1: Decimal relative humidity data
            2: Integral temperature data
            3: Decimal temperature data
            4: Checksum
        """
        # Convert the pulses to 40 bits
        binary = 0
        for idx in range(0, len(pulses), 2):
            binary = binary << 1 | int(pulses[idx] > HIGH_LEVEL)
 
        # Split into 5 bytes
        buffer = array.array("B")
        for shift in range(4, -1, -1):
            buffer.append(binary >> shift * 8 & 0xFF)
        return buffer
 
    def _verify_checksum(self, buffer):
        # Calculate checksum
        checksum = 0
        for buf in buffer[0:4]:
            checksum += buf
        if checksum & 0xFF != buffer[4]:
            raise InvalidChecksum()

💎ssd1306.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)

先将所需模块导入到micropython RP2040设备中

• 导入后，可以在设备信息文件栏看到。(如果Thonny软件没有将文件勾选上将看不到。)
  

🎯主程序代码

from machine import Pin, I2C
from ssd1306 import SSD1306_I2C
import utime as time
from dht import DHT11, InvalidChecksum
 
WIDTH  = 128                                            # oled display width
HEIGHT = 64                                             # oled display height
 
i2c = I2C(0, scl=Pin(9), sda=Pin(8), freq=200000)       # Init I2C using pins GP8 & GP9 (default I2C0 pins)
print("I2C Address      : "+hex(i2c.scan()[0]).upper()) # Display device address
print("I2C Configuration: "+str(i2c))                   # Display I2C config
 
 
oled = SSD1306_I2C(WIDTH, HEIGHT, i2c)                  # Init oled display
 
while True:
    time.sleep(1)
    pin = Pin(28, Pin.OUT, Pin.PULL_DOWN)
    sensor = DHT11(pin)
    t  = (sensor.temperature)
    h = (sensor.humidity)
    print("Temperature: ".format(sensor.temperature))
    print("Humidity: ".format(sensor.humidity))
    # Clear the oled display in case it has junk on it.
    oled.fill(0)       
    
    # Add some text
    oled.text("Temp: ",10,16)
    oled.text(str(sensor.temperature),50,16)
    oled.text("*C",90,16)
    
    oled.text("Humi: ",10,40)
    oled.text(str(sensor.humidity),50,40)
    oled.text("%",90,40)
    
    time.sleep(1)
    oled.show()

• Shell调试窗口输出dht传感器数据