【得捷电子Follow me第1期】+格式整理
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//内容一：3-5分钟短视频//
短视频：https://training.eeworld.com.cn/video/37028
GPS调试视频：https://training.eeworld.com.cn/course/68020
//内容二： 项目总结报告//
任务1：熟悉micropython的基本语法
通过Raspberry Pi Pico w开发板，熟悉固件下载、Mu Editor软件的基本使用方法、micropython的基本语法
搭配器件：Raspberry Pi Pico w开发板
主控板为PICOW，其特性如下：
• 采用了 Raspberry Pi 官方自主设计的 RP2040 微控制器芯片
• 搭载了双核 ARM Cortex M0 + 处理器，运行频率高达 133MHz 灵活时钟（可超频）
• 内置了 264KB 的 SRAM 和 2MB 的片上 Flash
• 板载2.4GHz无线接口芯片(802.11n或Wifi4)。
• 支持蓝牙 5.2
• 邮票孔设计，可直接焊接集成到用户自主设计的底板上
• USB1.1 主机和设备支持
• 支持低功耗睡眠和休眠模式
• 可识别为 USB 大容量存储器进行拖放式程序更新
• 多达 26 个多功能的 GPIO 引脚
• 2 个 SPI，2 个 I2C，2 个 UART，3 个 12 位 ADC，16 个可控 PWM 通道
• 精确的片上时钟和定时器
• 温度传感器
• 片上加速浮点库
• 8 个可编程 I/O (PIO) 状态机，用于自定义外设支持
引脚图可以在官方文档中找到：
PICOW有好多种开发方式，这次活动要求的是使用microPython进行开发，编译器这里我选择的是thonny，官网最新的是4.1.1，我用的是4.0.2，用起来感觉最新版的有BUG，程序上传起来比较麻烦。
thonny下载链接如下：下载
下载完编译器后我们就需要给picow刷上microPython固件，下载地址如下：下载
刷固件的方式是按住boot键以后上电，会出现U盘标志
然后把刚刚下载的固件刷进去即可。
然后就是板卡和picow的学习，其中对我帮助最大的就是这个博客：链接
其中详细的介绍了板卡各个外设的使用方法和microPython的语法，除此之外官方的文档也是必不可少的：
其中Pico_python_sdk详细的介绍了基础外设的使用方法
官方文档的参考也是必不可少的：链接
任务2：驱动外设
驱动LED、OLED显示屏、蜂鸣器等外设。
搭配器件：Raspberry Pi Pico w开发板、GROVE SHIELD、GROVE OLED扩展板、GROVE BUZZER扩展板
相信每一个开发板入手以后第一件事就是点灯，根据文档描述找到相应的驱动，代码如下：
import machine
import time
led = machine.Pin('LED', machine.Pin.OUT)
beep = machine.Pin(20,machine.Pin.OUT)
while (True):
led.on()
time.sleep(1)
led.off()
time.sleep(1)
编译烧录后可以观察到板卡上的LED每秒钟闪烁一次
下一个模块是蜂鸣器，官网资料如下：https://wiki.seeedstudio.com/Grove-Buzzer/#docusaurus_skipToContent_fallback
这里简单驱动蜂鸣器，在扩展板上接线是D20，所以驱动代码如下：
import machine
import time
led = machine.Pin('LED', machine.Pin.OUT)
beep = machine.Pin(20,machine.Pin.OUT)
while (True):
led.on()
beep.on()
time.sleep(1)
led.off()
beep.off()
time.sleep(1)
OLED 驱动
相关资料：https://wiki.seeedstudio.com/Grove-OLED-Display-0.96-SSD1315/
在群里大佬帮助下发现了github上有一个demo，下面是OLED驱动
# 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)
将驱动和下面的代码上传后，在屏幕上显示树莓派的标志
代码地址：
# Display Image & text on I2C driven ssd1306 OLED display
from machine import Pin, I2C
from ssd1306 import SSD1306_I2C
import framebuf
WIDTH = 128 # oled display width
HEIGHT = 32 # oled display height
i2c = I2C(0) # Init I2C using I2C0 defaults, SCL=Pin(GP9), SDA=Pin(GP8), freq=400000
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
# Raspberry Pi logo as 32x32 bytearray
buffer = bytearray(b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00|?\x00\x01\x86@\x80\x01\x01\x80\x80\x01\x11\x88\x80\x01\x05\xa0\x80\x00\x83\xc1\x00\x00C\xe3\x00\x00~\xfc\x00\x00L'\x00\x00\x9c\x11\x00\x00\xbf\xfd\x00\x00\xe1\x87\x00\x01\xc1\x83\x80\x02A\x82@\x02A\x82@\x02\xc1\xc2@\x02\xf6>\xc0\x01\xfc=\x80\x01\x18\x18\x80\x01\x88\x10\x80\x00\x8c!\x00\x00\x87\xf1\x00\x00\x7f\xf6\x00\x008\x1c\x00\x00\x0c \x00\x00\x03\xc0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00")
# Load the raspberry pi logo into the framebuffer (the image is 32x32)
fb = framebuf.FrameBuffer(buffer, 32, 32, framebuf.MONO_HLSB)
# Clear the oled display in case it has junk on it.
oled.fill(0)
# Blit the image from the framebuffer to the oled display
oled.blit(fb, 96, 0)
# Add some text
oled.text("Raspberry Pi",5,5)
oled.text("Pico",5,15)
# Finally update the oled display so the image & text is displayed
oled.show()
任务3：同步网络时间
学习network模块用法，掌握连接网络、查看网络参数等用法，实现通过网络同步系统时间。
搭配器件：Raspberry Pi Pico w开发板
与网络相关的资料可以参考开源库和官方文档Connecting-to-the-internet-with-pico-w
首先需要一个开源库ntptime来解析数据：
import utime
try:
import usocket as socket
except:
import socket
try:
import ustruct as struct
except:
import struct
# The NTP host can be configured at runtime by doing: ntptime.host = 'myhost.org'
host = "pool.ntp.org"
# The NTP socket timeout can be configured at runtime by doing: ntptime.timeout = 2
timeout = 1
def time():
NTP_QUERY = bytearray(48)
NTP_QUERY[0] = 0x1B
addr = socket.getaddrinfo(host, 123)[0][-1]
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
try:
s.settimeout(timeout)
res = s.sendto(NTP_QUERY, addr)
msg = s.recv(48)
finally:
s.close()
val = struct.unpack("!I", msg[40:44])[0]
EPOCH_YEAR = utime.gmtime(0)[0]
if EPOCH_YEAR == 2000:
# (date(2000, 1, 1) - date(1900, 1, 1)).days * 24*60*60
NTP_DELTA = 3155673600
elif EPOCH_YEAR == 1970:
# (date(1970, 1, 1) - date(1900, 1, 1)).days * 24*60*60
NTP_DELTA = 2208988800
else:
raise Exception("Unsupported epoch: {}".format(EPOCH_YEAR))
return val - NTP_DELTA
# There's currently no timezone support in MicroPython, and the RTC is set in UTC time.
def settime():
t = time()
import machine
tm = utime.gmtime(t)
machine.RTC().datetime((tm[0], tm[1], tm[2], tm[6] + 1, tm[3], tm[4], tm[5], 0))
时间测试代码：
import time
import network
ssid = 'xghdb24G'
password = 'aa123456789'
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
ntptime.settime()
from machine import RTC
rtc = RTC()
while(1):
print(rtc.datetime())
time.sleep(1)
运行完可以在thonny的shell端查看打印出来的时间
这里需要注意的ntptime库默认使用的是UTC0，北京时间处于UTC8，所以需要在ntptime库中的tm[3]后面加8
数据解析为machine.RTC().datetime((tm[0], tm[1], tm[2], tm[6] + 2, tm[3]+8, tm[4], tm[5], 0))
tm[0],tm[1],tm[2]分别为年月日，tm[3],tm[4],tm[5]对应小时分钟秒钟。
任务4：实现定位功能
掌握GNSS模块用法，实现定位功能。
建议搭配器件：Raspberry Pi Pico w开发板、GROVE - GPS扩展板
为了方便解析数据，我们引入了开源的解析库micropyGPS
micropyGPS是一个功能齐全的GPS NMEA句子解析器，用于MicroPython和PyBoard嵌入式平台。它也与Python 3.x完全兼容。
有如下特征
将大多数重要的 NMEA-0183 输出消息解析并验证为易于处理的数据结构
提供用于解释、显示、记录和操作 GPS 数据的帮助程序方法
用纯Python 3.x编写，仅使用Micropython中可用的标准库
在单个文件中作为单个类实现，以便轻松集成到嵌入式项目中
使用串行 UART 数据源编写的解析器;一次处理一个字符，为嘈杂的嵌入式环境提供强大的错误处理能力
micropyGPS基本使用方法
将 micropyGPS.py 复制到项目目录中，并将MicropyGPS类导入脚本。从那里，只需创建一个新的 GPS 对象并开始使用 update() 该方法向其提供数据。在向它提供完整的有效句子后，它将返回句子类型，并且内部 GPS 属性将更新。下面的示例显示了 RMC 句子的解析，对象返回包含当前纬度数据的元组。只要对象存在，它就会继续接受新字符并分析句子。解析的每种类型的句子都可以更新 GPS 对象中的不同内部属性。
"""
# MicropyGPS - a GPS NMEA sentence parser for Micropython/Python 3.X
# Copyright (c) 2017 Michael Calvin McCoy (calvin.mccoy@protonmail.com)
# The MIT License (MIT) - see LICENSE file
"""
# TODO:
# Time Since First Fix
# Distance/Time to Target
# More Helper Functions
# Dynamically limit sentences types to parse
from math import floor, modf
# Import utime or time for fix time handling
try:
# Assume running on MicroPython
import utime
except ImportError:
# Otherwise default to time module for non-embedded implementations
# Should still support millisecond resolution.
import time
class MicropyGPS(object):
"""GPS NMEA Sentence Parser. Creates object that stores all relevant GPS data and statistics.
Parses sentences one character at a time using update(). """
# Max Number of Characters a valid sentence can be (based on GGA sentence)
SENTENCE_LIMIT = 90
__HEMISPHERES = ('N', 'S', 'E', 'W')
__NO_FIX = 1
__FIX_2D = 2
__FIX_3D = 3
__DIRECTIONS = ('N', 'NNE', 'NE', 'ENE', 'E', 'ESE', 'SE', 'SSE', 'S', 'SSW', 'SW', 'WSW', 'W',
'WNW', 'NW', 'NNW')
__MONTHS = ('January', 'February', 'March', 'April', 'May',
'June', 'July', 'August', 'September', 'October',
'November', 'December')
def __init__(self, local_offset=0, location_formatting='ddm'):
"""
Setup GPS Object Status Flags, Internal Data Registers, etc
local_offset (int): Timzone Difference to UTC
location_formatting (str): Style For Presenting Longitude/Latitude:
Decimal Degree Minute (ddm) - 40° 26.767′ N
Degrees Minutes Seconds (dms) - 40° 26′ 46″ N
Decimal Degrees (dd) - 40.446° N
"""
#####################
# Object Status Flags
self.sentence_active = False
self.active_segment = 0
self.process_crc = False
self.gps_segments = []
self.crc_xor = 0
self.char_count = 0
self.fix_time = 0
#####################
# Sentence Statistics
self.crc_fails = 0
self.clean_sentences = 0
self.parsed_sentences = 0
#####################
# Logging Related
self.log_handle = None
self.log_en = False
#####################
# Data From Sentences
# Time
self.timestamp = [0, 0, 0.0]
self.date = [0, 0, 0]
self.local_offset = local_offset
# Position/Motion
self._latitude = [0, 0.0, 'N']
self._longitude = [0, 0.0, 'W']
self.coord_format = location_formatting
self.speed = [0.0, 0.0, 0.0]
self.course = 0.0
self.altitude = 0.0
self.geoid_height = 0.0
# GPS Info
self.satellites_in_view = 0
self.satellites_in_use = 0
self.satellites_used = []
self.last_sv_sentence = 0
self.total_sv_sentences = 0
self.satellite_data = dict()
self.hdop = 0.0
self.pdop = 0.0
self.vdop = 0.0
self.valid = False
self.fix_stat = 0
self.fix_type = 1
########################################
# Coordinates Translation Functions
########################################
@property
def latitude(self):
"""Format Latitude Data Correctly"""
if self.coord_format == 'dd':
decimal_degrees = self._latitude[0] + (self._latitude[1] / 60)
return [decimal_degrees, self._latitude[2]]
elif self.coord_format == 'dms':
minute_parts = modf(self._latitude[1])
seconds = round(minute_parts[0] * 60)
return [self._latitude[0], int(minute_parts[1]), seconds, self._latitude[2]]
else:
return self._latitude
@property
def longitude(self):
"""Format Longitude Data Correctly"""
if self.coord_format == 'dd':
decimal_degrees = self._longitude[0] + (self._longitude[1] / 60)
return [decimal_degrees, self._longitude[2]]
elif self.coord_format == 'dms':
minute_parts = modf(self._longitude[1])
seconds = round(minute_parts[0] * 60)
return [self._longitude[0], int(minute_parts[1]), seconds, self._longitude[2]]
else:
return self._longitude
########################################
# Logging Related Functions
########################################
def start_logging(self, target_file, mode="append"):
"""
Create GPS data log object
"""
# Set Write Mode Overwrite or Append
mode_code = 'w' if mode == 'new' else 'a'
try:
self.log_handle = open(target_file, mode_code)
except AttributeError:
print("Invalid FileName")
return False
self.log_en = True
return True
def stop_logging(self):
"""
Closes the log file handler and disables further logging
"""
try:
self.log_handle.close()
except AttributeError:
print("Invalid Handle")
return False
self.log_en = False
return True
def write_log(self, log_string):
"""Attempts to write the last valid NMEA sentence character to the active file handler
"""
try:
self.log_handle.write(log_string)
except TypeError:
return False
return True
########################################
# Sentence Parsers
########################################
def gprmc(self):
"""Parse Recommended Minimum Specific GPS/Transit data (RMC)Sentence.
Updates UTC timestamp, latitude, longitude, Course, Speed, Date, and fix status
"""
# UTC Timestamp
try:
utc_string = self.gps_segments[1]
if utc_string: # Possible timestamp found
hours = (int(utc_string[0:2]) + self.local_offset) % 24
minutes = int(utc_string[2:4])
seconds = float(utc_string[4:])
self.timestamp = [hours, minutes, seconds]
else: # No Time stamp yet
self.timestamp = [0, 0, 0.0]
except ValueError: # Bad Timestamp value present
return False
# Date stamp
try:
date_string = self.gps_segments[9]
# Date string printer function assumes to be year >=2000,
# date_string() must be supplied with the correct century argument to display correctly
if date_string: # Possible date stamp found
day = int(date_string[0:2])
month = int(date_string[2:4])
year = int(date_string[4:6])
self.date = (day, month, year)
else: # No Date stamp yet
self.date = (0, 0, 0)
except ValueError: # Bad Date stamp value present
return False
# Check Receiver Data Valid Flag
if self.gps_segments[2] == 'A': # Data from Receiver is Valid/Has Fix
# Longitude / Latitude
try:
# Latitude
l_string = self.gps_segments[3]
lat_degs = int(l_string[0:2])
lat_mins = float(l_string[2:])
lat_hemi = self.gps_segments[4]
# Longitude
l_string = self.gps_segments[5]
lon_degs = int(l_string[0:3])
lon_mins = float(l_string[3:])
lon_hemi = self.gps_segments[6]
except ValueError:
return False
if lat_hemi not in self.__HEMISPHERES:
return False
if lon_hemi not in self.__HEMISPHERES:
return False
# Speed
try:
spd_knt = float(self.gps_segments[7])
except ValueError:
return False
# Course
try:
if self.gps_segments[8]:
course = float(self.gps_segments[8])
else:
course = 0.0
except ValueError:
return False
# TODO - Add Magnetic Variation
# Update Object Data
self._latitude = [lat_degs, lat_mins, lat_hemi]
self._longitude = [lon_degs, lon_mins, lon_hemi]
# Include mph and hm/h
self.speed = [spd_knt, spd_knt * 1.151, spd_knt * 1.852]
self.course = course
self.valid = True
# Update Last Fix Time
self.new_fix_time()
else: # Clear Position Data if Sentence is 'Invalid'
self._latitude = [0, 0.0, 'N']
self._longitude = [0, 0.0, 'W']
self.speed = [0.0, 0.0, 0.0]
self.course = 0.0
self.valid = False
return True
def gpgll(self):
"""Parse Geographic Latitude and Longitude (GLL)Sentence. Updates UTC timestamp, latitude,
longitude, and fix status"""
# UTC Timestamp
try:
utc_string = self.gps_segments[5]
if utc_string: # Possible timestamp found
hours = (int(utc_string[0:2]) + self.local_offset) % 24
minutes = int(utc_string[2:4])
seconds = float(utc_string[4:])
self.timestamp = [hours, minutes, seconds]
else: # No Time stamp yet
self.timestamp = [0, 0, 0.0]
except ValueError: # Bad Timestamp value present
return False
# Check Receiver Data Valid Flag
if self.gps_segments[6] == 'A': # Data from Receiver is Valid/Has Fix
# Longitude / Latitude
try:
# Latitude
l_string = self.gps_segments[1]
lat_degs = int(l_string[0:2])
lat_mins = float(l_string[2:])
lat_hemi = self.gps_segments[2]
# Longitude
l_string = self.gps_segments[3]
lon_degs = int(l_string[0:3])
lon_mins = float(l_string[3:])
lon_hemi = self.gps_segments[4]
except ValueError:
return False
if lat_hemi not in self.__HEMISPHERES:
return False
if lon_hemi not in self.__HEMISPHERES:
return False
# Update Object Data
self._latitude = [lat_degs, lat_mins, lat_hemi]
self._longitude = [lon_degs, lon_mins, lon_hemi]
self.valid = True
# Update Last Fix Time
self.new_fix_time()
else: # Clear Position Data if Sentence is 'Invalid'
self._latitude = [0, 0.0, 'N']
self._longitude = [0, 0.0, 'W']
self.valid = False
return True
def gpvtg(self):
"""Parse Track Made Good and Ground Speed (VTG) Sentence. Updates speed and course"""
try:
course = float(self.gps_segments[1]) if self.gps_segments[1] else 0.0
spd_knt = float(self.gps_segments[5]) if self.gps_segments[5] else 0.0
except ValueError:
return False
# Include mph and km/h
self.speed = (spd_knt, spd_knt * 1.151, spd_knt * 1.852)
self.course = course
return True
def gpgga(self):
"""Parse Global Positioning System Fix Data (GGA) Sentence. Updates UTC timestamp, latitude, longitude,
fix status, satellites in use, Horizontal Dilution of Precision (HDOP), altitude, geoid height and fix status"""
try:
# UTC Timestamp
utc_string = self.gps_segments[1]
# Skip timestamp if receiver doesn't have on yet
if utc_string:
hours = (int(utc_string[0:2]) + self.local_offset) % 24
minutes = int(utc_string[2:4])
seconds = float(utc_string[4:])
else:
hours = 0
minutes = 0
seconds = 0.0
# Number of Satellites in Use
satellites_in_use = int(self.gps_segments[7])
# Get Fix Status
fix_stat = int(self.gps_segments[6])
except (ValueError, IndexError):
return False
try:
# Horizontal Dilution of Precision
hdop = float(self.gps_segments[8])
except (ValueError, IndexError):
hdop = 0.0
# Process Location and Speed Data if Fix is GOOD
if fix_stat:
# Longitude / Latitude
try:
# Latitude
l_string = self.gps_segments[2]
lat_degs = int(l_string[0:2])
lat_mins = float(l_string[2:])
lat_hemi = self.gps_segments[3]
# Longitude
l_string = self.gps_segments[4]
lon_degs = int(l_string[0:3])
lon_mins = float(l_string[3:])
lon_hemi = self.gps_segments[5]
except ValueError:
return False
if lat_hemi not in self.__HEMISPHERES:
return False
if lon_hemi not in self.__HEMISPHERES:
return False
# Altitude / Height Above Geoid
try:
altitude = float(self.gps_segments[9])
geoid_height = float(self.gps_segments[11])
except ValueError:
altitude = 0
geoid_height = 0
# Update Object Data
self._latitude = [lat_degs, lat_mins, lat_hemi]
self._longitude = [lon_degs, lon_mins, lon_hemi]
self.altitude = altitude
self.geoid_height = geoid_height
# Update Object Data
self.timestamp = [hours, minutes, seconds]
self.satellites_in_use = satellites_in_use
self.hdop = hdop
self.fix_stat = fix_stat
# If Fix is GOOD, update fix timestamp
if fix_stat:
self.new_fix_time()
return True
def gpgsa(self):
"""Parse GNSS DOP and Active Satellites (GSA) sentence. Updates GPS fix type, list of satellites used in
fix calculation, Position Dilution of Precision (PDOP), Horizontal Dilution of Precision (HDOP), Vertical
Dilution of Precision, and fix status"""
# Fix Type (None,2D or 3D)
try:
fix_type = int(self.gps_segments[2])
except ValueError:
return False
# Read All (up to 12) Available PRN Satellite Numbers
sats_used = []
for sats in range(12):
sat_number_str = self.gps_segments[3 + sats]
if sat_number_str:
try:
sat_number = int(sat_number_str)
sats_used.append(sat_number)
except ValueError:
return False
else:
break
# PDOP,HDOP,VDOP
try:
pdop = float(self.gps_segments[15])
hdop = float(self.gps_segments[16])
vdop = float(self.gps_segments[17])
except ValueError:
return False
# Update Object Data
self.fix_type = fix_type
# If Fix is GOOD, update fix timestamp
if fix_type > self.__NO_FIX:
self.new_fix_time()
self.satellites_used = sats_used
self.hdop = hdop
self.vdop = vdop
self.pdop = pdop
return True
def gpgsv(self):
"""Parse Satellites in View (GSV) sentence. Updates number of SV Sentences,the number of the last SV sentence
parsed, and data on each satellite present in the sentence"""
try:
num_sv_sentences = int(self.gps_segments[1])
current_sv_sentence = int(self.gps_segments[2])
sats_in_view = int(self.gps_segments[3])
except ValueError:
return False
# Create a blank dict to store all the satellite data from this sentence in:
# satellite PRN is key, tuple containing telemetry is value
satellite_dict = dict()
# Calculate Number of Satelites to pull data for and thus how many segment positions to read
if num_sv_sentences == current_sv_sentence:
# Last sentence may have 1-4 satellites; 5 - 20 positions
sat_segment_limit = (sats_in_view - ((num_sv_sentences - 1) * 4)) * 5
else:
sat_segment_limit = 20 # Non-last sentences have 4 satellites and thus read up to position 20
# Try to recover data for up to 4 satellites in sentence
for sats in range(4, sat_segment_limit, 4):
# If a PRN is present, grab satellite data
if self.gps_segments[sats]:
try:
sat_id = int(self.gps_segments[sats])
except (ValueError,IndexError):
return False
try: # elevation can be null (no value) when not tracking
elevation = int(self.gps_segments[sats+1])
except (ValueError,IndexError):
elevation = None
try: # azimuth can be null (no value) when not tracking
azimuth = int(self.gps_segments[sats+2])
except (ValueError,IndexError):
azimuth = None
try: # SNR can be null (no value) when not tracking
snr = int(self.gps_segments[sats+3])
except (ValueError,IndexError):
snr = None
# If no PRN is found, then the sentence has no more satellites to read
else:
break
# Add Satellite Data to Sentence Dict
satellite_dict[sat_id] = (elevation, azimuth, snr)
# Update Object Data
self.total_sv_sentences = num_sv_sentences
self.last_sv_sentence = current_sv_sentence
self.satellites_in_view = sats_in_view
# For a new set of sentences, we either clear out the existing sat data or
# update it as additional SV sentences are parsed
if current_sv_sentence == 1:
self.satellite_data = satellite_dict
else:
self.satellite_data.update(satellite_dict)
return True
##########################################
# Data Stream Handler Functions
##########################################
def new_sentence(self):
"""Adjust Object Flags in Preparation for a New Sentence"""
self.gps_segments = ['']
self.active_segment = 0
self.crc_xor = 0
self.sentence_active = True
self.process_crc = True
self.char_count = 0
def update(self, new_char):
"""Process a new input char and updates GPS object if necessary based on special characters ('$', ',', '*')
Function builds a list of received string that are validate by CRC prior to parsing by the appropriate
sentence function. Returns sentence type on successful parse, None otherwise"""
valid_sentence = False
# Validate new_char is a printable char
ascii_char = ord(new_char)
if 10 <= ascii_char <= 126:
self.char_count += 1
# Write Character to log file if enabled
if self.log_en:
self.write_log(new_char)
# Check if a new string is starting ($)
if new_char == '$':
self.new_sentence()
return None
elif self.sentence_active:
# Check if sentence is ending (*)
if new_char == '*':
self.process_crc = False
self.active_segment += 1
self.gps_segments.append('')
return None
# Check if a section is ended (,), Create a new substring to feed
# characters to
elif new_char == ',':
self.active_segment += 1
self.gps_segments.append('')
# Store All Other printable character and check CRC when ready
else:
self.gps_segments[self.active_segment] += new_char
# When CRC input is disabled, sentence is nearly complete
if not self.process_crc:
if len(self.gps_segments[self.active_segment]) == 2:
try:
final_crc = int(self.gps_segments[self.active_segment], 16)
if self.crc_xor == final_crc:
valid_sentence = True
else:
self.crc_fails += 1
except ValueError:
pass # CRC Value was deformed and could not have been correct
# Update CRC
if self.process_crc:
self.crc_xor ^= ascii_char
# If a Valid Sentence Was received and it's a supported sentence, then parse it!!
if valid_sentence:
self.clean_sentences += 1 # Increment clean sentences received
self.sentence_active = False # Clear Active Processing Flag
if self.gps_segments[0] in self.supported_sentences:
# parse the Sentence Based on the message type, return True if parse is clean
if self.supported_sentences[self.gps_segments[0]](self):
# Let host know that the GPS object was updated by returning parsed sentence type
self.parsed_sentences += 1
return self.gps_segments[0]
# Check that the sentence buffer isn't filling up with Garage waiting for the sentence to complete
if self.char_count > self.SENTENCE_LIMIT:
self.sentence_active = False
# Tell Host no new sentence was parsed
return None
def new_fix_time(self):
"""Updates a high resolution counter with current time when fix is updated. Currently only triggered from
GGA, GSA and RMC sentences"""
try:
self.fix_time = utime.ticks_ms()
except NameError:
self.fix_time = time.time()
#########################################
# User Helper Functions
# These functions make working with the GPS object data easier
#########################################
def satellite_data_updated(self):
"""
Checks if the all the GSV sentences in a group have been read, making satellite data complete
:return: boolean
"""
if self.total_sv_sentences > 0 and self.total_sv_sentences == self.last_sv_sentence:
return True
else:
return False
def unset_satellite_data_updated(self):
"""
Mark GSV sentences as read indicating the data has been used and future updates are fresh
"""
self.last_sv_sentence = 0
def satellites_visible(self):
"""
Returns a list of of the satellite PRNs currently visible to the receiver
:return: list
"""
return list(self.satellite_data.keys())
def time_since_fix(self):
"""Returns number of millisecond since the last sentence with a valid fix was parsed. Returns 0 if
no fix has been found"""
# Test if a Fix has been found
if self.fix_time == 0:
return -1
# Try calculating fix time using utime; if not running MicroPython
# time.time() returns a floating point value in secs
try:
current = utime.ticks_diff(utime.ticks_ms(), self.fix_time)
except NameError:
current = (time.time() - self.fix_time) * 1000 # ms
return current
def compass_direction(self):
"""
Determine a cardinal or inter-cardinal direction based on current course.
:return: string
"""
# Calculate the offset for a rotated compass
if self.course >= 348.75:
offset_course = 360 - self.course
else:
offset_course = self.course + 11.25
# Each compass point is separated by 22.5 degrees, divide to find lookup value
dir_index = floor(offset_course / 22.5)
final_dir = self.__DIRECTIONS[dir_index]
return final_dir
def latitude_string(self):
"""
Create a readable string of the current latitude data
:return: string
"""
if self.coord_format == 'dd':
formatted_latitude = self.latitude
lat_string = str(formatted_latitude[0]) + '° ' + str(self._latitude[2])
elif self.coord_format == 'dms':
formatted_latitude = self.latitude
lat_string = str(formatted_latitude[0]) + '° ' + str(formatted_latitude[1]) + "' " + str(formatted_latitude[2]) + '" ' + str(formatted_latitude[3])
else:
lat_string = str(self._latitude[0]) + '° ' + str(self._latitude[1]) + "' " + str(self._latitude[2])
return lat_string
def longitude_string(self):
"""
Create a readable string of the current longitude data
:return: string
"""
if self.coord_format == 'dd':
formatted_longitude = self.longitude
lon_string = str(formatted_longitude[0]) + '° ' + str(self._longitude[2])
elif self.coord_format == 'dms':
formatted_longitude = self.longitude
lon_string = str(formatted_longitude[0]) + '° ' + str(formatted_longitude[1]) + "' " + str(formatted_longitude[2]) + '" ' + str(formatted_longitude[3])
else:
lon_string = str(self._longitude[0]) + '° ' + str(self._longitude[1]) + "' " + str(self._longitude[2])
return lon_string
def speed_string(self, unit='kph'):
"""
Creates a readable string of the current speed data in one of three units
:param unit: string of 'kph','mph, or 'knot'
:return:
"""
if unit == 'mph':
speed_string = str(self.speed[1]) + ' mph'
elif unit == 'knot':
if self.speed[0] == 1:
unit_str = ' knot'
else:
unit_str = ' knots'
speed_string = str(self.speed[0]) + unit_str
else:
speed_string = str(self.speed[2]) + ' km/h'
return speed_string
def date_string(self, formatting='s_mdy', century='20'):
"""
Creates a readable string of the current date.
Can select between long format: Januray 1st, 2014
or two short formats:
11/01/2014 (MM/DD/YYYY)
01/11/2014 (DD/MM/YYYY)
:param formatting: string 's_mdy', 's_dmy', or 'long'
:param century: int delineating the century the GPS data is from (19 for 19XX, 20 for 20XX)
:return: date_string string with long or short format date
"""
# Long Format Januray 1st, 2014
if formatting == 'long':
# Retrieve Month string from private set
month = self.__MONTHS[self.date[1] - 1]
# Determine Date Suffix
if self.date[0] in (1, 21, 31):
suffix = 'st'
elif self.date[0] in (2, 22):
suffix = 'nd'
elif self.date[0] == (3, 23):
suffix = 'rd'
else:
suffix = 'th'
day = str(self.date[0]) + suffix # Create Day String
year = century + str(self.date[2]) # Create Year String
date_string = month + ' ' + day + ', ' + year # Put it all together
else:
# Add leading zeros to day string if necessary
if self.date[0] < 10:
day = '0' + str(self.date[0])
else:
day = str(self.date[0])
# Add leading zeros to month string if necessary
if self.date[1] < 10:
month = '0' + str(self.date[1])
else:
month = str(self.date[1])
# Add leading zeros to year string if necessary
if self.date[2] < 10:
year = '0' + str(self.date[2])
else:
year = str(self.date[2])
# Build final string based on desired formatting
if formatting == 's_dmy':
date_string = day + '/' + month + '/' + year
else: # Default date format
date_string = month + '/' + day + '/' + year
return date_string
# All the currently supported NMEA sentences
supported_sentences = {'GPRMC': gprmc, 'GLRMC': gprmc,
'GPGGA': gpgga, 'GLGGA': gpgga,
'GPVTG': gpvtg, 'GLVTG': gpvtg,
'GPGSA': gpgsa, 'GLGSA': gpgsa,
'GPGSV': gpgsv, 'GLGSV': gpgsv,
'GPGLL': gpgll, 'GLGLL': gpgll,
'GNGGA': gpgga, 'GNRMC': gprmc,
'GNVTG': gpvtg, 'GNGLL': gpgll,
'GNGSA': gpgsa,
}
if __name__ == "__main__":
pass
测试代码如下
from machine import UART, Pin
import time
import hashlib
from micropyGPS import MicropyGPS
import framebuf
uart0 = UART(0, baudrate=9600, tx=Pin(0), rx=Pin(1))
time.sleep(0.1)
rxData = bytes()
my_gps = MicropyGPS()
while True:
if uart0.any():
stat = my_gps.update(uart0.read(1).decode('ascii')) # Note the conversion to to chr, UART outputs ints normally
if stat:
print('my_gps.latitude:', my_gps.latitude_string())
print('my_gps.longitude:', my_gps.longitude_string())
stat = None
time.sleep(1)
运行后会打印出当前的经纬度，my_gps.Latitude_string（）表示经度，my_gps.Longitude_string（）表示维度
这个需要在开阔的地方来接受信号，在室内时好时坏，录视频的时候还要去天台接受信号
测试效果如下：
打开网页查询对比一下
对本次活动的心得体会
感谢得捷和eeword的活动，让我有机会体验树莓派PICOW的开发，希望活动能继续办下去。
本次活动学习了microPython基础语法，学会了一些简单外设的驱动，学会了如何在thonny中如何编译下载程序，如何点亮一块OLED屏幕，也学习了如何使用开源库来完成项目，多学习借鉴代码对自己项目的完成有很大的帮助。
这次活动没有用上树莓派PICO特色的PIO外设，因为时间和自己的拖延症没有完成任务五是这次活动非常可惜的地方，希望后面可以自己学习一下PICO其他的功能，让这个板子不至于去吃灰。
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