如何用raw_input控制脉宽调制

Question

我尝试使用raw_input函数输入一个字母，如l或r，它将是一个特定的PWM值，如0.4或1.6。下面是我的代码：

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

GPIO.cleanup()

enable_pin = 18
coil_A_1_pin = 27
coil_A_2_pin = 17
coil_B_1_pin = 23
coil_B_2_pin = 24
coil_A_x1_pin = 22
coil_A_x2_pin = 5
coil_B_x1_pin = 6
coil_B_x2_pin = 13

s = 12
GPIO.setup(enable_pin, GPIO.OUT)
GPIO.setup(coil_A_1_pin, GPIO.OUT)
GPIO.setup(coil_A_2_pin, GPIO.OUT)
GPIO.setup(coil_B_1_pin, GPIO.OUT)
GPIO.setup(coil_B_2_pin, GPIO.OUT)
GPIO.setup(coil_A_x1_pin, GPIO.OUT)
GPIO.setup(coil_A_x2_pin, GPIO.OUT)
GPIO.setup(coil_B_x1_pin, GPIO.OUT)
GPIO.setup(coil_B_x2_pin, GPIO.OUT)
GPIO.setup(s, GPIO.OUT)

GPIO.output(enable_pin, 1)

def forward(delay, steps):  
  for i in range(0, steps):
    setStep(1, 1, 0, 0)
    time.sleep(delay)
    setStep(0, 1, 1, 0)
    time.sleep(delay)
    setStep(0, 0, 1, 1)
    time.sleep(delay)
    setStep(1, 0, 0, 1)
    time.sleep(delay)

def backwards(delay, steps):  
  for i in range(0, steps):
    setStep(1, 0, 0, 1)
    time.sleep(delay)
    setStep(0, 0, 1, 1)
    time.sleep(delay)
    setStep(0, 1, 1, 0)
    time.sleep(delay)
    setStep(1, 1, 0, 0)
    time.sleep(delay)


def setStep(w1, w2, w3, w4):
  GPIO.output(coil_A_1_pin, w1)
  GPIO.output(coil_A_x1_pin, w1)
  GPIO.output(coil_A_2_pin, w2)
  GPIO.output(coil_A_x2_pin, w2)
  GPIO.output(coil_B_1_pin, w3)
  GPIO.output(coil_B_x1_pin, w3)
  GPIO.output(coil_B_2_pin, w4)
  GPIO.output(coil_B_x2_pin, w4)


p = GPIO.PWM(s,7.5) 


try:
  while True:
    l = 0.3
    r = 1.7
    n = 1.1
    pos = raw_input("Left(l), right(r) or neutral(n)? ")
    p.ChangeDutyCycle(float(pos))
    delay = raw_input("Delay between steps (milliseconds)? ")
    steps = raw_input("How many steps forward? ")
    forward(int(delay) / 1000.0, int(steps))
    steps = raw_input("How many steps backwards? ")
    backwards(int(delay) / 1000.0, int(steps))
except KeyboardInterrupt:
  GPIO.cleanup()

我也有另一个程序可以在pygame上做到这一点，但我不知道如何在开发模式的chromebook上通过ssh使用它，所以我放弃了它。也不要介意我的步进电机的所有def和其他东西，我也在运行。步进电机工作得很好，因为我直接输入数字，而不是变量，但我不知道如何让它与变量一起工作。另外，如果有人告诉我如何在chromebook上通过ssh运行pygame，那就太棒了，这会让它变得容易得多！

Answer 1

对于变量pos，您应该使用input而不是raw_input。

基本上，s = input('Say: ')做的事情与

s = eval( raw_input('Say: ') )

即给定的输入字符串将被求值。那么你甚至不需要对它做一个浮动。