为什么这个 Arduino 代码不能正确褪色，而 Python 等效代码可以？

Question

我正在尝试为我的 Arduino Uno 编写一个程序，该程序使用 RGB LED 慢慢淡出不同的颜色。问题是，它不是慢慢褪色，而是快速闪烁几种不同的颜色，然后仅淡出几种颜色。然后它重复这种模式，但颜色不同。我写了 Python 等价物，它正常消失。

这是 Arduino 代码：

bool operation[3] = {false, true, false};

const int RLED = 11;
const int BLED = 9;
const int GLED = 10;

int rval = 1000;
int gval = 500;
int bval = 0;

void setup() {
  // Initialize the pins
  pinMode(RLED, OUTPUT);
  pinMode(BLED, OUTPUT);
  pinMode(GLED, OUTPUT);
}

void loop() {
  // Set whether we are adding or subtracting from the val variables
  // true is adding, false is subtracting
  if (rval >= 1000) operation[0] = false;
  else if (rval <= 0) operation[0] = true;
  if (gval >= 1000) operation[1] = false;
  else if (gval <= 0) operation[1] = true;
  if (bval >= 1000) operation[2] = false;
  else if (bval <= 0) operation[2] = true;

  // Add or subtract from the val variables, according to the bools
  if (operation[0]) rval++;
  else rval--;
  if (operation[1]) gval++;
  else gval--;
  if (operation[2]) bval++;
  else bval--;

  // Set the LED's color
  analogWrite(RLED, rval);
  analogWrite(BLED, bval);
  analogWrite(GLED, gval);
  delay(10);
}

这是 Python 等效项（使用 tkinter window 而不是 LED）：

import time
import tkinter

root = tkinter.Tk()

rval = 1000
gval = 500
bval = 10
operation = [True, False, True]

def map(x, xmax, xmin, ymax, ymin):
    return ((ymax - ymin) / (xmax - xmin)) * x

while True:
    # Set whether we are adding or subtracting the val variables
    # True is adding, False is subtracting
    if rval >= 1000: operation[0] = False
    elif rval <= 0: operation[0] = True
    if gval >= 1000: operation[1] = False
    elif gval <= 0: operation[1] = True
    if bval >= 1000: operation[2] = False
    elif bval <= 0: operation[2] = True

    # Add or subtract from the val variables, according to the bools
    if operation[0]: rval += 1
    else: rval -= 1
    if operation[1]: gval += 1
    else: gval -= 1
    if operation[2]: bval += 1
    else: bval -= 1

    # Convert from RGB to hex. This is required to set the window's color
    rmapped = int(map(rval, 1000, 0, 255, 0))
    gmapped = int(map(gval, 1000, 0, 255, 0))
    bmapped = int(map(bval, 1000, 0, 255, 0))

    # Set the window's color
    root.config(bg="#%02x%02x%02x" % (rmapped, gmapped, bmapped))
    root.update()
    time.sleep(0.01)

我的问题：两者有什么区别？为什么 Arduino 代码不能正常运行，而 Python 代码可以？

Answer 1

事实证明，我认为 1024 是 Uno 的最大 analogWrite() 值，而实际上 255。循环运行完美；但只有当 val 变量小于或等于 255 时，灯光才会正确变暗。当 val 变量高于 255 时，颜色处于最大亮度；他们不能再亮了。因此，当 val 大于 255 时，颜色不会发生变化。这就是导致颜色闪烁的原因。

要解决此问题，只需将 Arduino 代码中出现的所有 1000 替换为 255。

为什么这个 Arduino 代码不能正确褪色，而 Python 等效代码可以？

Why does this Arduino code not color-fade correctly, while the Python equivalent does?

python

arduino