我目前正在开发一个项目，该项目需要使用 termios 作为串行通信手段，在 g++ 编译程序和 Arduino ATMega2560 之间进行串行通信。g++ 程序发送由 Arduino 解析的 5 个 uint8_t 值的数组。然后 Arduino 使用这些字节来打开条带上的特定 LED。
下面是用 g++ 编译的 C++ 程序的代码：
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <termios.h>
#include <inttypes.h>
#include <fcntl.h>
#include <fstream>
#include <iostream>
#define BAUD B115200
#define ARDUINO "/dev/ttyACM0"
using namespace std;
struct termios old_io, new_io;
int arduinoFD, c, res;
int main (int argc, char* argv[]) {
arduinoFD = open(ARDUINO, O_RDWR | O_NOCTTY);
if (arduinoFD < 0){perror(ARDUINO); exit(EXIT_FAILURE);}
new_io.c_cflag = BAUD | CRTSCTS | CS8 | CLOCAL | CREAD;
new_io.c_iflag = IGNPAR | ICRNL;
new_io.c_oflag = 0;
new_io.c_lflag = ICANON;
cfsetospeed(&new_io, BAUD);
cfsetispeed(&new_io, BAUD);
tcflush(arduinoFD, TCOFLUSH);
//Byte that tells the arduino to start parsing.
uint8_t* STARTCMD = (uint8_t*)malloc(1);
STARTCMD[0]=0x0A;
write(arduinoFD, STARTCMD, 1);
//Enable debugging.
STARTCMD[0]=(uint8_t)'d';
write(arduinoFD, STARTCMD, 1);
while(true){
//Allocate array for LED info.
uint8_t* testWrite = (uint8_t*)malloc(5);
for(uint8_t i = 0; i < 240; i++){
//Loop through all LEDs, setting their (R,G,B) to (220,220,220).
testWrite[0] = 0x73; // 's'
testWrite[1] = 0xc8; // Red - 220
testWrite[2] = 0xc8; // Green - 220
testWrite[3] = 0xc8; // Blue - 220
testWrite[4] = (uint8_t)i; // Led Address - i
//Print out the values to stdout.
char* outPrint = (char*)malloc(17);
sprintf(outPrint, "R%03dG%03dB%03dL%03d\n",
testWrite[1], testWrite[2], testWrite[3], testWrite[4]);
fwrite(outPrint,17,1,stdout);
//Send the values from the buffer to the arduino, then sleep for 24 milliseconds.
write(arduinoFD, testWrite, 4);
usleep(24*1000);
}
//Deallocate the buffer and reallocate a space to send the update value.
free(testWrite);
testWrite = (uint8_t*)malloc(1);
testWrite[0] = (uint8_t)'z';
write(arduinoFD, testWrite, 1);
//Deallocate and sleep for 550ms.
free(testWrite);
usleep(550*1000);
}
}
这是 Arduino 草图：#include
Adafruit_NeoPixel strip = Adafruit_NeoPixel(240, 6, NEO_GRB + NEO_KHZ800);
int pinRangeStart = 0;
int pinRangeStop = 0;
char inByte;
uint8_t* colorBytes;
boolean debug = false;
void setup(){
Serial.begin(115200);
while(!Serial);
Serial.print("Desktop LED Ambience\n");
strip.begin();
strip.show();
}
void loop(){
while(Serial.available() > 0){
while(Serial.read() != 0x0A);
Serial.print("Start Byte read!");
while(true){
//inByte is the first of 5 bytes to be read. The other four are (R,G,B,L) where
//R = Red
//G = Green
//B = Blue
//L = LED Number.
inByte = Serial.read();
switch(inByte){
case('r'): {
for(int i = 0 ; i < strip.numPixels(); i++)
strip.setPixelColor(i, strip.Color(0,0,0));
strip.show();
Serial.println("Reset!");
Serial.flush();
break;
}
case('d'): {
Serial.print("Debugging ");
debug =! debug;
if(!debug)
Serial.println("DISABLED");
else
Serial.println("ENABLED");
break;
}
case('s'): {
colorBytes = new uint8_t[4];
colorBytes[0] = Serial.read(); // Red
colorBytes[1] = Serial.read(); // Green
colorBytes[2] = Serial.read(); // Blue
colorBytes[3] = Serial.read(); // LED Number
if(debug){
Serial.println("Set lights without updating.");
Serial.print("R=");
Serial.println(colorBytes[0]);
Serial.print("G=");
Serial.println(colorBytes[1]);
Serial.print("B=");
Serial.println(colorBytes[2]);
Serial.print("LED=");
Serial.println(colorBytes[3]);
}
uint32_t newColor = strip.Color(colorBytes[0], colorBytes[1], colorBytes[2]);
strip.setPixelColor(colorBytes[3], newColor);
break;
}
case('z'): {
strip.show();
Serial.println("Updating Lights");
break;
}
}
}
}
}
g++ 程序的输出可以显示为一组字节，分组在一起{}表示对write().
{0x0a}
{0x64}
{0x73 0xc8 0xc8 0xc8 0x00}
{0x73 0xc8 0xc8 0xc8 0x01}
{...}
{0x73 0xc8 0xc8 0xc8 0xee}
{0x73 0xc8 0xc8 0xc8 0xef}
{0x7a}
arduino 可以很好地拾取前两个字节，并将每组 5 个发送的第一个字节正确解释为 0x73（也称为“s”），但是该组中的以下字节未正确读取并最终被解释由 Arduino 作为 255 的值。
预期的输出是：
Desktop LED Ambience
Start Byte read!
Debugging ENABLED
Set lights without updating.
R=200
G=200
B=200
LED=0
Set lights without updating.
R=200
G=200
B=200
LED=1
...
Set lights without updating.
R=200
G=200
B=200
LED=238
Set lights without updating.
R=200
G=200
B=200
LED=239
Updating Lights
这是实际的输出：
Desktop LED Ambience
Start Byte read!
Debugging ENABLED
Set lights without updating.
R=255
G=255
B=255
LED=255
Set lights without updating.
R=255
G=255
B=255
LED=255
...
Set lights without updating.
R=255
G=255
B=255
LED=255
Set lights without updating.
R=255
G=255
B=255
LED=255
Updating Lights
有人会碰巧知道是什么导致我的代码出现这种情况吗？起初我以为总线已经饱和，所以我尝试将波特率降低到 19600，但它没有解决任何问题。
编辑：另一个问题是，在设置 LED 的四五次迭代之后，绿色通道随机退出，所以 Arduino 得到的只是一个更加错误的 {'s', 255, 0, 255, 255}。