[筆記]使用Micropython 結合 ESP32 基於SPI介面的SSD1306 OLED

好久沒貼文了，2021新年快樂。

這次紀錄的是在ESP32跑在Micropython，並且接SPI的SSD1306 OLED

包含函示庫與接線方式

一、ESP32的SPI有分HSPI (id=1)與VSPI (id=2)

兩者腳位分別為：

SPI(1)

sck = GPIO14

mosi = GPIO13

miso = GPIO12

SPI(2)

sck = GPIO18

mosi = GPIO23

miso = GPIO19

二、OLED為四線式SPI，我買的長這樣(圖片)

OLED腳位分別為：GND、VCC、D0(sck)、D1(mosi)、RES、DC、CS

三、連接方法為：

OLED          ESP32

GND  <─>  GND

VCC  <─>  3.3V

D0      <─> GPIO18

D1     <─>  GPIO23

RES   <─> GPIO26

DC     <─> GPIO19

CS      <─> GPIO5

如果要使用SPI(1)則把GPIO18與GPIO23接為GPIO14與GPIO13即可。

四、測試程式Test.py

主程式必須先import OLED的函示庫，函示庫在文尾。

import ssd1306

from machine import Pin,SPI

spi = SPI(2, sck=Pin(18), mosi=Pin(23))

res = Pin(26)

dc = Pin(19)

cs = Pin(5)

oled = ssd1306.SSD1306_SPI(128,64,spi,dc,res,cs)

oled.text('Hello, World 1!', 0, 0)

oled.show()

五、SSD1306.py的Library：

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)