在microbit上写一百多行程序,因内存太小就要崩溃。
于是,把我的四驱车的掌控板电机驱动就弄了出来。扩展板还是使用DFROBOT出品的电机驱动扩展板,此扩展板兼容掌控板和microbit. 并可同时支持四个电机,8个servo.
四驱车清单:
- 四驱车(在淘宝上花二十几元买一个四驱车)
- 电机扩展板,
- 掌控板或microbit板
- 小车电源(我使用的是家里的小米移动电源)
程序清单:
- pca9685.py
- df_motor.py
代码: 全选
import ustruct
import time
class PCA9685:
def __init__(self, i2c, address=0x40):
self.i2c = i2c
self.address = address
self.reset()
def _write(self, address, value):
self.i2c.writeto_mem(self.address, address, bytearray([value]))
def _read(self, address):
return self.i2c.readfrom_mem(self.address, address, 1)[0]
def reset(self):
self._write(0x00, 0x00) # Mode1
def freq(self, freq=None):
if freq is None:
return int(25000000.0 / 4096 / (self._read(0xfe) - 0.5))
prescale = int(25000000.0 / 4096.0 / freq + 0.5)
old_mode = self._read(0x00) # Mode 1
self._write(0x00, (old_mode & 0x7F) | 0x10) # Mode 1, sleep
self._write(0xfe, prescale) # Prescale
self._write(0x00, old_mode) # Mode 1
time.sleep_us(5)
self._write(0x00, old_mode | 0xa1) # Mode 1, autoincrement on
def pwm(self, index, on=None, off=None):
if on is None or off is None:
data = self.i2c.readfrom_mem(self.address, 0x06 + 4 * index, 4)
return ustruct.unpack('<HH', data)
data = ustruct.pack('<HH', on, off)
self.i2c.writeto_mem(self.address, 0x06 + 4 * index, data)
def duty(self, index, value=None, invert=False):
if value is None:
pwm = self.pwm(index)
if pwm == (0, 4096):
value = 0
elif pwm == (4096, 0):
value = 4095
value = pwm[1]
if invert:
value = 4095 - value
return value
if not 0 <= value <= 4095:
raise ValueError("Out of range")
if invert:
value = 4095 - value
if value == 0:
self.pwm(index, 0, 4096)
elif value == 4095:
self.pwm(index, 4096, 0)
else:
self.pwm(index, 0, value)
代码: 全选
import pca9685
CW, CCW = 1, -1
M1, M2, M3, M4 = 0, 1, 2, 3
class DF_Motors:
def __init__(self, i2c):
self.pca = pca9685.PCA9685(i2c)
self.pca.freq(500)
self.motorList = [[7, 6], [5, 4], [3, 2], [1, 0]]
# 设置电机功率最小值,防止因功率太小,电机不转
self.speed_min = 30
# speed 电机速度,取值0-255
def run(self, motorIndex, direction, speed=100 ):
if motorIndex not in range(4):
return 0
if speed < 0:
speed = 0
elif speed > 255:
speed = 255
if direction not in [CW, CCW]:
return 0
if direction == CW:
channel_high, channel_low = self.motorList[motorIndex]
else:
channel_low, channel_high = self.motorList[motorIndex]
if speed < self.speed_min:
self.pca.duty(channel_low, 0)
self.pca.duty(channel_high, 0)
else:
self.pca.duty(channel_low, 0)
self.pca.duty(channel_high, speed*16)
if __name__ == "__main__":
from machine import I2C, Pin
import time
i2c = I2C(scl=Pin(Pin.P19), sda=Pin(Pin.P20), freq=400000)
motors = DF_Motors(i2c)
motors.speed_min = 60
for i in range(4):
motors.run(i, -1, 100)
time.sleep_ms(5000)
for i in range(4):
motors.run(i, 1, 0)