O_勘智K210环境搭建
O_嵌入式专题目录
K210产品介绍
- 嘉楠勘智K210产品官网
- 矽速AI模组官网
- 亚博智能K210开发者套件
Win10下某些版本可能打开错误，换其它版本或使用命令行版本即可。
MaixPy IDE
注：以下所有MaixPy代码均基于MaixHub默认配置固件+lodepng内置模块配置。
Maix M1W Dock自检例程 - MaixPy 暂停更新
#------------------------------------------------------------------------------#
# SelfCheck_DockM1W.py - By: AaronTempletonYin - Fri Apr 9 2021
# LCD, CAM, KPU, FFT, SYS
# FPIOA, GPIO, I2C, PWM, SPI, TIMER, UART, I2S, WDT
# Freq, Reset, Utils, Video, Audio, Network
#------------------------------------------------------------------------------#
import gc, sys, os, time
from machine import Timer, UART
import Maix
from fpioa_manager import fm
from board import board_info
flagLCD = 2
flagCAM = 2
flagKPU = 2
flagFFT = 2
flagSYS = 2
flagFPIOA = 2
flagGPIO = 2
flagI2C = 2
flagPWM = 2
flagSPI = 2
flagTIMER = 2
flagUART = 2
flagI2S = 2
flagWDT = 2
flagVideo = 2
flagAudio = 2
flagNetwork = 2
# LCD -------------------------------------------------------------------------#
import lcd
def CheckList():
global flagLCD, flagCAM, flagKPU, flagFFT, flagSYS
global flagGPIO, flagI2C, flagPWM, flagSPI, flagTIMER, flagUART, flagI2S, flagWDT
global flagVideo, flagAudio, flagNetwork
lcd.fill_rectangle(10, 10, lcd.width()-20, 90, lcd.BLACK)
if flagLCD == 0:
lcd.draw_string(10, 10, "LCD", lcd.RED, lcd.BLACK)
elif flagLCD == 1:
lcd.draw_string(10, 10, "LCD", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(10, 10, "LCD", lcd.WHITE, lcd.BLACK)
if flagCAM == 0:
lcd.draw_string(70, 10, "CAM", lcd.RED, lcd.BLACK)
elif flagCAM == 1:
lcd.draw_string(70, 10, "CAM", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(70, 10, "CAM", lcd.WHITE, lcd.BLACK)
if flagKPU == 0:
lcd.draw_string(130, 10, "KPU", lcd.RED, lcd.BLACK)
elif flagKPU == 1:
lcd.draw_string(130, 10, "KPU", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(130, 10, "KPU", lcd.WHITE, lcd.BLACK)
if flagFFT == 0:
lcd.draw_string(190, 10, "FFT", lcd.RED, lcd.BLACK)
elif flagFFT == 1:
lcd.draw_string(190, 10, "FFT", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(190, 10, "FFT", lcd.WHITE, lcd.BLACK)
if flagSYS == 0:
lcd.draw_string(250, 10, "SYS", lcd.RED, lcd.BLACK)
elif flagSYS == 1:
lcd.draw_string(250, 10, "SYS", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(250, 10, "SYS", lcd.WHITE, lcd.BLACK)
if flagFPIOA == 0:
lcd.draw_string(10, 30, "FPIOA", lcd.RED, lcd.BLACK)
elif flagFPIOA == 1:
lcd.draw_string(10, 30, "FPIOA", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(10, 30, "FPIOA", lcd.WHITE, lcd.BLACK)
if flagGPIO == 0:
lcd.draw_string(70, 30, "GPIO", lcd.RED, lcd.BLACK)
elif flagGPIO == 1:
lcd.draw_string(70, 30, "GPIO", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(70, 30, "GPIO", lcd.WHITE, lcd.BLACK)
if flagI2C == 0:
lcd.draw_string(130, 30, "I2C", lcd.RED, lcd.BLACK)
elif flagI2C == 1:
lcd.draw_string(130, 30, "I2C", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(130, 30, "I2C", lcd.WHITE, lcd.BLACK)
if flagPWM == 0:
lcd.draw_string(190, 30, "PWM", lcd.RED, lcd.BLACK)
elif flagPWM == 1:
lcd.draw_string(190, 30, "PWM", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(190, 30, "PWM", lcd.WHITE, lcd.BLACK)
if flagSPI == 0:
lcd.draw_string(250, 30, "SPI", lcd.RED, lcd.BLACK)
elif flagSPI == 1:
lcd.draw_string(250, 30, "SPI", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(250, 30, "SPI", lcd.WHITE, lcd.BLACK)
if flagTIMER == 0:
lcd.draw_string(10, 50, "TIMER", lcd.RED, lcd.BLACK)
elif flagTIMER == 1:
lcd.draw_string(10, 50, "TIMER", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(10, 50, "TIMER", lcd.WHITE, lcd.BLACK)
if flagUART == 0:
lcd.draw_string(70, 50, "UART", lcd.RED, lcd.BLACK)
elif flagUART == 1:
lcd.draw_string(70, 50, "UART", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(70, 50, "UART", lcd.WHITE, lcd.BLACK)
if flagI2S == 0:
lcd.draw_string(130, 50, "I2S", lcd.RED, lcd.BLACK)
elif flagI2S == 1:
lcd.draw_string(130, 50, "I2S", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(130, 50, "I2S", lcd.WHITE, lcd.BLACK)
if flagWDT == 0:
lcd.draw_string(190, 50, "WDT", lcd.RED, lcd.BLACK)
elif flagWDT == 1:
lcd.draw_string(190, 50, "WDT", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(190, 50, "WDT", lcd.WHITE, lcd.BLACK)
if flagVideo == 0:
lcd.draw_string(10, 70, "Video", lcd.RED, lcd.BLACK)
elif flagVideo == 1:
lcd.draw_string(10, 70, "Video", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(10, 70, "Video", lcd.WHITE, lcd.BLACK)
if flagAudio == 0:
lcd.draw_string(70, 70, "Audio", lcd.RED, lcd.BLACK)
elif flagAudio == 1:
lcd.draw_string(70, 70, "Audio", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(70, 70, "Audio", lcd.WHITE, lcd.BLACK)
if flagNetwork == 0:
lcd.draw_string(130, 70, "Network", lcd.RED, lcd.BLACK)
elif flagNetwork == 1:
lcd.draw_string(130, 70, "Network", lcd.GREEN, lcd.BLACK)
else:
lcd.draw_string(130, 70, "Network", lcd.WHITE, lcd.BLACK)
def DisplayFor(seconds, height):
for i in range(seconds):
lcd.fill_rectangle(10, height, lcd.width()-20, 20, lcd.BLACK)
lcd.draw_string(145, height, "{}".format(seconds-i), lcd.WHITE, lcd.BLACK)
time.sleep(1)
def InitLCD():
# "color=lcd.RGB565" in default
lcd.init(freq=15000000)
# Rotation 0-3
lcd.rotation(0)
def CheckLCD():
global flagLCD
InitLCD()
lcd.fill_rectangle(10, 130, lcd.width()-20, 60, lcd.BLACK)
lcd.draw_string(100, 130, "LCD init done.", lcd.WHITE, lcd.BLACK)
flagLCD = 1
CheckList()
# CAM TIMER -------------------------------------------------------------------#
import sensor, image
def onCamTimer(timerC):
global camCount
camCount += 1
print('S: ', camCount)
camCount = 0
camTimer = Timer(Timer.TIMER0, Timer.CHANNEL0, mode=Timer.MODE_PERIODIC, period=1, unit=Timer.UNIT_S, callback=onCamTimer, arg=None, start=False, priority=1, div=0)
def InitCAM():
lcd.fill_rectangle(10, 130, lcd.width()-20, 60, lcd.BLACK)
lcd.draw_string(80, 130, "Init CAM & TIMER ...", lcd.WHITE, lcd.BLACK)
sensor.reset(freq=20000000, dual_buff=True)
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.QVGA)
sensor.skip_frames()
#sensor.set_hmirror(True)
sensor.set_vflip(True)
def CheckCAMandTIMER():
global camCount, flagCAM, flagTIMER
InitCAM()
lcd.fill_rectangle(10, 130, lcd.width()-20, 60, lcd.BLACK)
lcd.draw_string(110, 130, "CAM id: %x" % sensor.get_id(), lcd.WHITE, lcd.BLACK)
lcd.draw_string(95, 150, "TIMER time: 5s", lcd.WHITE, lcd.BLACK)
time.sleep(3)
camCount = 0
camTimer.start()
#sensor.set_contrast(0)
#sensor.set_brightness(0)
#sensor.set_auto_gain(1)
while 1:
if camCount >5:
sensor.run(0)
# Shutdown the camera if enable is False
sensor.shutdown(False)
lcd.clear()
camTimer.stop()
flagCAM = 1
flagTIMER = 1
CheckList()
lcd.fill_rectangle(10, 130, lcd.width()-20, 60, lcd.BLACK)
lcd.draw_string(70, 130, "CAM & TIMER test done.", lcd.WHITE, lcd.BLACK)
break
img = sensor.snapshot()
lcd.display(img)
#import KPU as KPU
# SYS -------------------------------------------------------------------------#
def CheckSYS():
global flagSYS
lcd.fill_rectangle(10, 130, lcd.width()-20, 60, lcd.BLACK)
lcd.draw_string(70, 130, "CPU frequence: {} MHz".format(Maix.freq.get_cpu()), lcd.WHITE, lcd.BLACK)
lcd.draw_string(70, 150, "KPU frequence: {} MHz".format(Maix.freq.get_kpu()), lcd.WHITE, lcd.BLACK)
lcd.draw_string(90, 170, "Heap size: {}".format(Maix.utils.gc_heap_size()), lcd.WHITE, lcd.BLACK)
flagSYS = 1
CheckList()
# FPIOA GPIO ------------------------------------------------------------------#
def onLedTimer(timerL):
global ledState
#print(ledState)
if ledState == 1:
ledState += 1
ledRDock.value(0)
ledGDock.value(1)
ledBDock.value(1)
elif ledState == 2:
ledState += 1
ledRDock.value(1)
ledGDock.value(0)
ledBDock.value(1)
elif ledState == 3:
ledState += 1
ledRDock.value(1)
ledGDock.value(1)
ledBDock.value(0)
elif ledState == 4:
ledState += 1
ledRDock.value(0)
ledGDock.value(0)
ledBDock.value(1)
elif ledState == 5:
ledState += 1
ledRDock.value(0)
ledGDock.value(1)
ledBDock.value(0)
elif ledState == 6:
ledState += 1
ledRDock.value(1)
ledGDock.value(0)
ledBDock.value(0)
elif ledState == 7:
ledState += 1
ledRDock.value(0)
ledGDock.value(0)
ledBDock.value(0)
else:
ledState = 1
ledRDock.value(1)
ledGDock.value(1)
ledBDock.value(1)
fm.register(12, fm.fpioa.GPIO1)
ledBDock = Maix.GPIO(Maix.GPIO.GPIO1, Maix.GPIO.OUT)
ledBDock.value(1)
fm.register(13, fm.fpioa.GPIO2)
ledGDock = Maix.GPIO(Maix.GPIO.GPIO2, Maix.GPIO.OUT)
ledGDock.value(1)
fm.register(14, fm.fpioa.GPIO3)
ledRDock = Maix.GPIO(Maix.GPIO.GPIO3, Maix.GPIO.OUT)
ledRDock.value(1)
ledState = 1
ledTimer = Timer(Timer.TIMER1, Timer.CHANNEL0, mode=Timer.MODE_PERIODIC, period=1, unit=Timer.UNIT_S, callback=onLedTimer, arg=None, start=False, priority=1, div=0)
def CheckFPIOAandGPIO():
global flagFPIOA, flagGPIO
ledTimer.start()
lcd.fill_rectangle(10, 130, lcd.width()-20, 60, lcd.BLACK)
lcd.draw_string(70, 130, "FPIOA & GPIO init done.", lcd.WHITE, lcd.BLACK)
lcd.draw_string(76, 150, "Please check RGB led.", lcd.WHITE, lcd.BLACK)
flagFPIOA = 1
flagGPIO = 1
CheckList()
DisplayFor(8, 170)
ledTimer.stop()
ledRDock.value(1)
ledGDock.value(1)
ledBDock.value(1)
def MainCheck():
CheckLCD()
DisplayFor(1, 150)
#CheckCAMandTIMER()
#CheckSYS()
CheckFPIOAandGPIO()
MainCheck()
Maix M1W Dock人脸识别例程 - MaixPy
注意烧录的MaixPy固件必须支持kmodel。
import sensor
import image
import lcd
import KPU as kpu
import time
from Maix import FPIOA, GPIO
import gc
from fpioa_manager import fm
from board import board_info
import utime
# Sipeed offical demo, flash to SPIFFS, see https://www.maixhub.com/modelInfo?modelId=14
#task_fd = kpu.load(0x300000)
#task_ld = kpu.load(0x400000)
#task_fe = kpu.load(0x500000)
# Put models to SD card, notice that the filename must be correct
task_fd = kpu.load("/sd/FaceDetection.smodel")
task_ld = kpu.load("/sd/FaceLandmarkDetection.smodel")
task_fe = kpu.load("/sd/FeatureExtraction.smodel")
clock = time.clock()
fm.register(board_info.BOOT_KEY, fm.fpioa.GPIOHS0)
key_gpio = GPIO(GPIO.GPIOHS0, GPIO.IN)
start_processing = False
BOUNCE_PROTECTION = 50
def set_key_state(*_):
global start_processing
start_processing = True
utime.sleep_ms(BOUNCE_PROTECTION)
key_gpio.irq(set_key_state, GPIO.IRQ_RISING, GPIO.WAKEUP_NOT_SUPPORT)
lcd.init()
sensor.reset(dual_buff=True)
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.QVGA)
sensor.set_hmirror(1)
sensor.set_vflip(1)
sensor.run(1)
anchor = (1.889, 2.5245, 2.9465, 3.94056, 3.99987, 5.3658, 5.155437,
6.92275, 6.718375, 9.01025) # anchor for face detect
dst_point = [(44, 59), (84, 59), (64, 82), (47, 105),
(81, 105)] # standard face key point position
a = kpu.init_yolo2(task_fd, 0.5, 0.3, 5, anchor)
img_lcd = image.Image()
img_face = image.Image(size=(128, 128))
a = img_face.pix_to_ai()
record_ftr = []
record_ftrs = []
names = ['Mr.1', 'Mr.2', 'Mr.3', 'Mr.4', 'Mr.5',
'Mr.6', 'Mr.7', 'Mr.8', 'Mr.9', 'Mr.10']
ACCURACY = 85
while (1):
img = sensor.snapshot()
clock.tick()
code = kpu.run_yolo2(task_fd, img)
if code:
for i in code:
# Cut face and resize to 128x128
a = img.draw_rectangle(i.rect())
face_cut = img.cut(i.x(), i.y(), i.w(), i.h())
face_cut_128 = face_cut.resize(128, 128)
a = face_cut_128.pix_to_ai()
# a = img.draw_image(face_cut_128, (0,0))
# Landmark for face 5 points
fmap = kpu.forward(task_ld, face_cut_128)
plist = fmap[:]
le = (i.x() + int(plist[0] * i.w() - 10), i.y() + int(plist[1] * i.h()))
re = (i.x() + int(plist[2] * i.w()), i.y() + int(plist[3] * i.h()))
nose = (i.x() + int(plist[4] * i.w()), i.y() + int(plist[5] * i.h()))
lm = (i.x() + int(plist[6] * i.w()), i.y() + int(plist[7] * i.h()))
rm = (i.x() + int(plist[8] * i.w()), i.y() + int(plist[9] * i.h()))
a = img.draw_circle(le[0], le[1], 4)
a = img.draw_circle(re[0], re[1], 4)
a = img.draw_circle(nose[0], nose[1], 4)
a = img.draw_circle(lm[0], lm[1], 4)
a = img.draw_circle(rm[0], rm[1], 4)
# align face to standard position
src_point = [le, re, nose, lm, rm]
T = image.get_affine_transform(src_point, dst_point)
a = image.warp_affine_ai(img, img_face, T)
a = img_face.ai_to_pix()
# a = img.draw_image(img_face, (128,0))
del (face_cut_128)
# calculate face feature vector
fmap = kpu.forward(task_fe, img_face)
feature = kpu.face_encode(fmap[:])
reg_flag = False
scores = []
for j in range(len(record_ftrs)):
score = kpu.face_compare(record_ftrs[j], feature)
scores.append(score)
max_score = 0
index = 0
for k in range(len(scores)):
if max_score < scores[k]:
max_score = scores[k]
index = k
if max_score > ACCURACY:
a = img.draw_string(i.x(), i.y(), ("%s :%2.1f" % (
names[index], max_score)), color=(0, 255, 0), scale=2)
else:
a = img.draw_string(i.x(), i.y(), ("X :%2.1f" % (
max_score)), color=(255, 0, 0), scale=2)
if start_processing:
record_ftr = feature
record_ftrs.append(record_ftr)
start_processing = False
break
fps = clock.fps()
print("%2.1f fps" % fps)
a = lcd.display(img)
gc.collect()
# kpu.memtest()
# a = kpu.deinit(task_fe)
# a = kpu.deinit(task_ld)
# a = kpu.deinit(task_fd)Kendeyte IDE
- Github
- Gitee
- Official - beta
下载解压后双击
KendryteIDE.bat，首次运行会自动下载安装并配置环境。- 嘉楠C/FreeRTOS SDK及官方KD233开发板资料
- 嘉楠BBS
其它
错误集锦
OSError: no available NIC
没有连接网络。
MaixPy内部定义视频尺寸
（实测Camera只能用QVGA。）
typedef enum { FRAMESIZE_INVALID = 0, // C/SIF Resolutions FRAMESIZE_QQCIF, // 88x72 FRAMESIZE_QCIF, // 176x144 FRAMESIZE_CIF, // 352x288 FRAMESIZE_QQSIF, // 88x60 FRAMESIZE_QSIF, // 176x120 FRAMESIZE_SIF, // 352x240 // VGA Resolutions FRAMESIZE_QQQQVGA, // 40x30 FRAMESIZE_QQQVGA, // 80x60 FRAMESIZE_QQVGA, // 160x120 FRAMESIZE_QVGA, // 320x240 FRAMESIZE_VGA, // 640x480 FRAMESIZE_HQQQVGA, // 60x40 FRAMESIZE_HQQVGA, // 120x80 FRAMESIZE_HQVGA, // 240x160 // FFT Resolutions FRAMESIZE_64X32, // 64x32 FRAMESIZE_64X64, // 64x64 FRAMESIZE_128X64, // 128x64 FRAMESIZE_128X128, // 128x128 FRAMESIZE_240X240, // 240x240 // Other FRAMESIZE_LCD, // 128x160 FRAMESIZE_QQVGA2, // 128x160 FRAMESIZE_WVGA, // 720x480 FRAMESIZE_WVGA2, // 752x480 FRAMESIZE_SVGA, // 800x600 FRAMESIZE_SXGA, // 1280x1024 FRAMESIZE_UXGA, // 1600x1200 } framesize_t;
ESPAT库
注：实际使用时http获取返回头会很慢，有待优化。
from network_espat import wifi
def EspatInit():
if LCD_DEBUG == 1:
lcd.clear()
lcd.rotation(1)
lcd.draw_string(50, 150, "Network initing ...", lcd.WHITE, lcd.BLACK)
SSID = "K210T"
PASW = "00000000"
if wifi.isconnected() == False:
for i in range(5):
try:
wifi.reset()
print(wifi.at_cmd("AT\r\n"))
print(wifi.at_cmd("AT+GMR\r\n"))
print("STA mode: ", wifi._at_cmd("AT+CWMODE_DEF=1\r\n"))
print("Auto connect: ", wifi._at_cmd("AT+CWAUTOCONN=1\r\n"))
print(wifi.at_cmd("AT+CIPSTATUS\r\n"))
print("Try AT connect wifi ...", wifi._at_cmd())
if LCD_DEBUG == 1:
lcd.clear()
lcd.draw_string(30, 150, "Try AT connect wifi ...", lcd.WHITE, lcd.BLACK)
lcd.draw_string(110, 170, "{}".format(5-i), lcd.WHITE, lcd.BLACK)
wifi.connect(SSID, PASW)
if wifi.isconnected():
break
except Exception as e:
print(e)
if wifi.isconnected() == True:
print("Network state: {} - {} - {}".format(wifi.isconnected(), wifi.ifconfig()[6], wifi.ifconfig()[0]))
if LCD_DEBUG == 1:
lcd.clear()
lcd.draw_string(65, 130, "Network state:", lcd.WHITE, lcd.BLACK)
lcd.draw_string(65, 150, "{}".format(wifi.ifconfig()[6]), lcd.WHITE, lcd.BLACK)
lcd.draw_string(65, 170, "{}".format(wifi.ifconfig()[0]), lcd.WHITE, lcd.BLACK)MQTT库
from umqtt_simple import MQTTClient
def mqttCallback(topic, msg):
print((topic, msg))
lcd.fill_rectangle(10, 180, lcd.width()-20, 20, lcd.BLACK)
lcd.draw_string(35, 180, ": %s" % msg, lcd.WHITE, lcd.BLACK)
if topic != b'':
lcd.fill_rectangle(10, 150, lcd.width()-20, 20, lcd.BLACK)
lcd.draw_string(35, 150, "Subscribe to %s" % topic, lcd.WHITE, lcd.BLACK)
mqttClientId = "7d54f85af42976ee3c2693e6xxxxxxxx"
mqttServer = "bemfa.com"
mqttPort = 9501
mqttTopic = b"K210T1"
mqttC = MQTTClient(mqttClientId, mqttServer, mqttPort)
def MqttInit():
if LCD_DEBUG == 1:
lcd.clear()
lcd.draw_string(70, 10, "{}".format(wifi.ifconfig()[0]), lcd.WHITE, lcd.BLACK)
lcd.draw_string(50, 150, "Mqtt connecting ...", lcd.WHITE, lcd.BLACK)
mqttC.set_callback(mqttCallback)
mqttC.connect()
mqttC.subscribe(mqttTopic, qos=0)
print("Connected to %s:%s, subscribed to %s topic." % (mqttServer, mqttPort, mqttTopic))
mqttC.publish(mqttTopic, b"K210T1 online.")
if LCD_DEBUG == 1:
lcd.fill_rectangle(10, 150, lcd.width()-20, 20, lcd.BLACK)
lcd.draw_string(65, 150, "Mqtt connected.", lcd.WHITE, lcd.BLACK)
while 1:
if 0:
# Blocking wait for message
mqttC.wait_msg()
else:
# Non-blocking wait for message
mqttC.check_msg()
# Then need to sleep to avoid 100% CPU usage (in a real
# app other useful actions would be performed instead)
time.sleep(1)
mqttC.disconnect()local variable xxx referenced before assignment
在Python中有一个经典错误：
local variable xxx referenced before assignment
#赋值前引用的局部变量xxx这里引入两个概念：
局部变量指的在函数内部定义并使用的变量，它只在函数内部有效。
全局变量指的是能作用于函数内外的变量，即全局变量既可以在各个函数的外部使用，也可以在各函数内部使用。
- Test_1:
def main():
num=5
print(num)
main()
print(num)#NameError: name 'num' is not defined这里是提示num没有被定义，因为num属于在main函数内部的变量，在函数体外面是不会被调用，解释器也不会认识这个num变量，只有当main函数调用时，才可以获得其内部一些变量，这就是局部变量。
def main():
global num
num=5
print(num)
main()
print(num)使用global声明num为全局变量就可以了，但是应当注意，在项目中，定义全局变量会造成进程死锁。
- Test_2:
num=10
def main():
print(num)
num=5
print(num)
main()
print(num)UnboundLocalError: local variable 'num' referenced before assignment这就是赋前引用局部变量，num在main函数外界定义一次，但在main函数内部又定义一次，python将优先处理在函数体内的变量，且调用在定义之前，所以在第三行print(num)报错，后面num变量赋值num=5让num=10失去全局效果。
- Test_3:
global num
num=10
def main():
print(num)
num=5
print('main:{}'.format(num))
main()
print(num)声明num 为全局变量后，依然报错赋前引用局部变量，则就进一步说明在函数体内部自称一体，num为全局变量，只能保证在函数体内部认识这个num变量，但在函数体内部对num变量进行的改变，依然要保证先赋值后调用。
global num
num=10
def main():
#print(num)
num=5
print('main:{}'.format(num))
main()
print(num)main:5
10global num
num=10
def main():
#print(num)
#num=5
print('main:{}'.format(num))
main()
print(num)main:10
10num=10
def main():
global num
print(num)
num=5
print('main:{}'.format(num))
main()
print('外部:{}'.format(num))10
main:5
外部:5可以通过三个例子进一步总结。
Python 命名空间查找顺序:
假设我们要使用变量 runoob，则 Python 的查找顺序为：局部的命名空间去 -> 全局命名空间 -> 内置命名空间。
如果找不到变量 runoob，它将放弃查找并引发一个 NameError 异常：NameError: name ‘runoob’ is not defined。
在实际运用中：
@app.route('/',methods=['GET','POST'])
def index():
if request.method == 'POST':
text='你好'
#return render_template('index.html',text=text)
return render_template('index.html',text=text) 在flask中text传入前端，就会报错 local variable text referenced before assignment，解决方案就是取消注释那一句，讲最后一句text删除。
实际上这个错误可以归结于变量作用域问题，参考文章：https://www.cnblogs.com/fireporsche/p/7813961.html
版权声明：本文为CSDN博主「菜鸟上路_lbz」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/qq_44198436/article/details/100051651
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