ESP32 + MRCIOPYTHON◕‿◕

ADC

基准电压 和 输入信号衰减量

ESP32内部ADC的基准电压通常为 1.1V，不同封装可能会略有不同。
ADC在接近基准电压时线性较差（特别是在较高衰减时），其最低测量电压约为 100mV，低于或等于100mV的电压读数为0，也就是说不能用ESP32直接测量低于100mv的电压。

ADC的基准电压为1.1V，所以，ESP32的ADC在无衰减的情况下，能测量的电压范围为100mV至950mV，要读取高于基准电压的电压，就需要使用atten参数指定输入衰减。其有效值（近似线性测量范围）为：

ADC.ATTN_0DB：无衰减（100mV - 950mV） 
ADC.ATTN_2_5DB：2.5dB 衰减（100mV - 1250mV） 
ADC.ATTN_6DB：6dB 衰减（150mV - 1750mV） 
ADC.ATTN_11DB：11dB 衰减（150mV - 2450mV） 

代码 和 函数

from machine import Pin
from machine import ADC
import time
def main():
    pin = Pin(39, Pin.IN)
    adc = ADC(pin) 
    adc.atten(ADC.ATTN_11DB) #指定输入信号衰减量
    val = adc.read()
    print(val)  

adc.read()会读取出来4095
read_u16()会读出来65535

OLED (SSD1306)

# 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)
 

from machine import Pin
import machine
from utime import sleep
from ssd1306 import SSD1306_I2C

sleepSpan=1.5

sda=Pin(25)
scl=Pin(26)

i2c=machine.I2C(0,sda=sda,scl=scl,freq=400000)
oled=SSD1306_I2C(128,32,i2c)

while True:
    #在指定位置显示文字 str x y 
    oled.text("MicroPython",0,10)
    oled.text("C",10,20)
    oled.show()
    sleep(sleepSpan)
    #奇数时反相显示，偶数时正常显示
    oled.invert(1)
    sleep(sleepSpan)
    oled.invert(0)
    sleep(sleepSpan)
    #填满屏幕
    oled.fill(1)
    oled.show()
    sleep(sleepSpan)
    #调整亮度。0最暗，255最亮
    oled.contrast(32)
    sleep(sleepSpan)
    oled.contrast(255)
    #清空屏幕
    oled.fill(0)
    #在指定位置绘制点
    oled.pixel(100, 32, 1)
    oled.line(5,5,123,5,1)
    oled.rect(15,15,80,40,1)
    oled.fill_rect(25,25,40,20,1)
    oled.show()
    sleep(sleepSpan)
    #清空屏幕
    oled.fill(0)
    oled.show()
    sleep(sleepSpan)