@kidswong999
那为什么我用两种方法得到的结果不一样呢？

@kidswong999
试过了 程序可以运行 但是舵机无法运动

import time
from machine import I2C, Pin
#from pyb import I2C

#i2c = I2C(2, I2C.MASTER) # The i2c bus must always be 2.
#print(i2c.scan())

i2c = I2C(sda=Pin('P5'), scl=Pin('P4'))
print(i2c.scan())

如果使用pyb库的scan方法 ， 返回空的列表
如图

如果使用machine 库的scan方法 ， 返回全部地址 ，但是我只连接了一个 PCA9685
如图

PCA9685我用的是这款
如图

如果直接运行例程中的main 没有报错 但是舵机无法转动 ，也没有产生PWM波
舵机我用的是 MG995 检测PWM的方法是 L298N+ 小马达
外接了一个5v电源

# Blob Detection Example
#
# This example shows off how to use the find_blobs function to find color
# blobs in the image. This example in particular looks for dark green objects.

import sensor, image, time
import car
from pid import PID

# You may need to tweak the above settings for tracking green things...
# Select an area in the Framebuffer to copy the color settings.

sensor.reset() # Initialize the camera sensor.
sensor.set_pixformat(sensor.RGB565) # use RGB565.
sensor.set_framesize(sensor.QQVGA) # use QQVGA for speed.
sensor.skip_frames(10) # Let new settings take affect.
sensor.set_auto_whitebal(False) # turn this off.
clock = time.clock() # Tracks FPS.

# For color tracking to work really well you should ideally be in a very, very,
# very, controlled enviroment where the lighting is constant...
green_threshold   = (76, 96, -110, -30, 8, 66)
size_threshold = 2000
x_pid = PID(p=0.5, i=1, imax=100)
h_pid = PID(p=0.05, i=0.1, imax=50)

def find_max(blobs):
    max_size=0
    for blob in blobs:
        if blob[2]*blob[3] > max_size:
            max_blob=blob
            max_size = blob[2]*blob[3]
    return max_blob

while(True):
    clock.tick() # Track elapsed milliseconds between snapshots().
    img = sensor.snapshot() # Take a picture and return the image.

    blobs = img.find_blobs([green_threshold])
    if blobs:
        max_blob = find_max(blobs)
        x_error = max_blob[5]-img.width()/2
        h_error = max_blob[2]*max_blob[3]-size_threshold
        print("x error: ", x_error)
        '''
        for b in blobs:
            # Draw a rect around the blob.
            img.draw_rectangle(b[0:4]) # rect
            img.draw_cross(b[5], b[6]) # cx, cy
        '''
        img.draw_rectangle(max_blob[0:4]) # rect
        img.draw_cross(max_blob[5], max_blob[6]) # cx, cy
        x_output=x_pid.get_pid(x_error,1)
        h_output=h_pid.get_pid(h_error,1)
        print("h_output",h_output)
        car.run(-h_output-x_output,-h_output+x_output)
    else:
        car.run(18,-18)

上一段代码中的

def find_max(blobs):
    max_size=0
    for blob in blobs:
        if blob[2]*blob[3] > max_size:
            max_blob=blob
            max_size = blob[2]*blob[3]
    return max_blob

需要添加‘’global max_blob''一句 否则在反复接收函数值时会报错
具体参考https://www.cnblogs.com/zhaijiahui/p/8398480.html

如果没有 怎么实现goto的功能