[经验分享] 【得捷电子Follow me第1期】+ 任务3 网络时间同步到OLED上

alanlan86 2023-6-1 11:38 楼主

经过前面两个实验任务，我们对于picoW的使用，对于micropython的调试都有了初步的认识，接着我们需要发挥picoW上无线WiFi的功能，并且综合了OLED的显示将NTP网络时间同步到OLED显示上。

（1）硬件准备

在开始动手调试OLED前，先下载OLED屏幕相关资料以及硬件接线图进行一个了解。

Grove - OLED Display 0.96" (SSD1315) I2C Interface Compatible with Arduino - Seeed Studio

从原理图上面需要注意

A、OLED屏幕引出是I2C接口的，默认不改变ADDR脚的下拉，地址是0x78(8位地址格式）。若需要修改地址，可以改变为上拉。

B、SCL和SDA做了3.3V和5V电平兼容的

C、在底板上将OLED的I2C接到Grove的I2C1上，SCL=GP7 SDA=GP6

（2）软件准备

A、OLED显示

从micropython example中下载ssd1306的示例代码，如下：

# 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)

验证OLED输出Hello World显示：

from ssd1306 import SSD1306_I2C
from machine import Pin, I2C
from time import sleep

i2c = I2C(1, scl=Pin(7), sda=Pin(6), freq=400000)  # Grove - OLED Display 0.96" (SSD1315)

oled = SSD1306_I2C(128, 64, i2c)

while True:
    oled.fill(0)  # clear
    oled.text("Hello,World!", 0, 0)
    oled.show()
    #sleep(0.5)

此处，从网络摘取的示例代码存在一个问题，当配置I2C时钟为200K时，将出现如下错误告警，将实在配置为400KHz，则可以正常显示Helloworld字样！

B、WiFi联网

在micropython的固件中，已经对于LWIP的网络协议栈以及WIFI的驱动部分做了大量工作，因为用户只需简单的引入network网络包，调用connect等接口即可轻松简单便捷实现WiFi联网功能。联网成功后将输出ip地址

import network
import time

ssid = 'XXX'
password = 'XXXXX'

wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect(ssid, password)

# Wait for connect or fail
max_wait = 10
while max_wait > 0:
    if wlan.status() < 0 or wlan.status() >= 3:
        break
    max_wait -= 1
    print('waiting for connection...')
    time.sleep(1)

# Handle connection error
if wlan.status() != 3:
    raise RuntimeError('network connection failed')
else:
    print('connected')
    status = wlan.ifconfig()
    print('ip = ' + status[0])

（3）调试实验

import network
import time
from time import sleep
from ssd1306 import SSD1306_I2C
from machine import Pin, I2C

ssid = 'XXXXX'
password = 'XXXXX'

wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect(ssid, password)

# Wait for connect or fail
max_wait = 10
while max_wait > 0:
    if wlan.status() < 0 or wlan.status() >= 3:
        break
    max_wait -= 1
    print('waiting for connection...')
    time.sleep(1)

# Handle connection error
if wlan.status() != 3:
    raise RuntimeError('network connection failed')
else:
    print('connected')
    status = wlan.ifconfig()
    print('ip = ' + status[0])

import ntptime
def sync_ntp():
     ntptime.NTP_DELTA = 3155644800   # 可选 UTC+8偏移时间（秒），不设置就是UTC0
     ntptime.host = 'ntp1.aliyun.com'  # 可选，ntp服务器，默认是"pool.ntp.org"
     ntptime.settime()   # 修改设备时间,到这就已经设置好了

sync_ntp()

from machine import RTC
from time import sleep

i2c = I2C(1, scl=Pin(7), sda=Pin(6), freq=400000)  # Grove - OLED Display 0.96" (SSD1315)
oled = SSD1306_I2C(128, 64, i2c)
oled.fill(0)  # clear
oled.text("NTP Time!", 0, 0)
oled.show()
while True:
    rtc = RTC()
    print(rtc.datetime())
    oled.fill(0)  # clear
    oled.text("NTP Time!", 0, 0)
    s = ','.join(str(i) for i in rtc.datetime())
    oled.text(s, 0, 16)
    oled.show()
    sleep(1)

在REPL窗口输出：