以下内容部分为网络收集和整理，为个人学习笔记复习使用
串口 Serial
用于控制板和一台计算机或其他设备之间的通信。所有的控制板有至少一个串口(又称作为UART或USART)。它通过0(RX)和1(TX)数字引脚经过串口转换芯片连接计算机USB端口与计算机进行通信。因此，如果你使用这些功能的同时你不能使用引脚0和1作为输入或输出。
Mega2560 有三个额外的串口：Serial 1使用19(RX)和18(TX)，Serial 2使用17(RX)和16(TX)，Serial3使用15(RX)和14(TX)。
串口、COM口是指的物理接口形式(硬件)。而TTL、RS-232、RS-485是指的电平标准(电信号)
TTL串口设备 TTL标准是低电平为0，高电平为1（+5V电平）
- 高电平3.6~5V，
- 低电平0V~2.4V
RS232串口; 标准是正电平为0，负电平为1
- －15v ~ －3v 代表1
- ＋3v ~ ＋15v 代表0
Serial 1通过0(RX)和1(TX)
将TX引脚连接到您的设备的RX引脚，将RX引脚连接到您的设备的TX引脚
内置的串口监视器：点击工具栏上的串口监视器按钮
调用begin()函数（选择相同的波特率）。
函数
if (Serial)
指定的串口是否准备好
available()
获取已经传输到，并存储在串行接收缓冲区（能够存储64个字节）的数据的有效的字节数（字符）。
begin()
设置串行数据传输速率 位/秒（波特）
end()
停用串行通信，使RX和TX引脚用于一般输入和输出。要重新使用串行通信, 需要 Serial.begin()语句。
find()
Serial.find(target)从串行缓冲器中读取数据，直到发现给定长度的目标字符串。如果找到目标字符串，该函数返回true，如果超时则返回false
findUntil()
从串行缓冲区读取数据，直到找到一个给定的长度或字符串终止位。
flush()
等待超出的串行数据完成传输。（不再是丢弃所有进入缓存器的串行数据。）
parseFloat()
从串口缓冲区返回第一个有效的浮点数
parseInt()
查找传入的串行数据流中的下一个有效的整数
peek()
返回传入的串行数据的下一个字节（字符），而不是进入内部串行缓冲器调取。也就是说，连续调用 peek()将返回相同的字符，与调用read()方法相同。
print()
以人们可读的ASCII文本形式打印数据到串口输出
println()
输出人们可识别的ASCII码文本并回车 (ASCII 13, 或 '\r') 及换行(ASCII 10, 或 '\n')
read()
读取传入的串口的数据，返回传入的串口数据的第一个字节（或-1，如果没有可用的数据）
readBytes()
从串口读字符到一个缓冲区
readBytesUntil()
将字符从串行缓冲区读取到一个数组，直到检测到终止字符，或预设的读取长度读取完毕，或者时间到了
setTimeout()
设置使用Serial.readBytesUntil() 或Serial.readBytes()时等待串口数据的最大毫秒值. 默认为1000毫秒
write()
写入二制数据到串口。发送的数据以一个字节或者一系列的字节为单位。如果写入的数字为字符，需使用print()命令进行代替。
SerialEvent()
在数据可用时调用，使用Serial.read()来捕获这些数据。注：目前的serialEvent()不与ATMEGA32U4核心兼容。
示例
文件 示例 \examples\04.Communication
Graph
void setup() {
// initialize the serial communication:
Serial.begin(9600);
}
void loop() {
// send the value of analog input 0:
Serial.println(analogRead(A0));
// wait a bit for the analog-to-digital converter
// to stabilize after the last reading:
delay(2);
}
Physical Pixel
const int ledPin = 13; // the pin that the LED is attached to
int incomingByte; // a variable to read incoming serial data into
void setup() {
// initialize serial communication:
Serial.begin(9600);
// initialize the LED pin as an output:
pinMode(ledPin, OUTPUT);
}
void loop() {
// see if there's incoming serial data:
if (Serial.available() > 0) {
// read the oldest byte in the serial buffer:
incomingByte = Serial.read();
// if it's a capital H (ASCII 72), turn on the LED:
if (incomingByte == 'H') {
digitalWrite(ledPin, HIGH);
}
// if it's an L (ASCII 76) turn off the LED:
if (incomingByte == 'L') {
digitalWrite(ledPin, LOW);
}
}
}
Dimmer
const int ledPin = 9; // the pin that the LED is attached to
void setup() {
// initialize the serial communication:
Serial.begin(9600);
// initialize the ledPin as an output:
pinMode(ledPin, OUTPUT);
}
void loop() {
byte brightness;
// check if data has been sent from the computer:
if (Serial.available()) {
// read the most recent byte (which will be from 0 to 255):
brightness = Serial.read();
// set the brightness of the LED:
analogWrite(ledPin, brightness);
}
}
Virtual Color Mixer
const int redPin = A0; // sensor to control red color
const int greenPin = A1; // sensor to control green color
const int bluePin = A2; // sensor to control blue color
void setup() {
Serial.begin(9600);
}
void loop() {
Serial.print(analogRead(redPin));
Serial.print(",");
Serial.print(analogRead(greenPin));
Serial.print(",");
Serial.println(analogRead(bluePin));
}
ReadASCIIString
// pins for the LEDs:
const int redPin = 3;
const int greenPin = 5;
const int bluePin = 6;
void setup() {
// initialize serial:
Serial.begin(9600);
// make the pins outputs:
pinMode(redPin, OUTPUT);
pinMode(greenPin, OUTPUT);
pinMode(bluePin, OUTPUT);
}
void loop() {
// if there's any serial available, read it:
while (Serial.available() > 0) {
// look for the next valid integer in the incoming serial stream:
int red = Serial.parseInt();
// do it again:
int green = Serial.parseInt();
// do it again:
int blue = Serial.parseInt();
// look for the newline. That's the end of your
// sentence:
if (Serial.read() == '\n') {
// constrain the values to 0 - 255 and invert
// if you're using a common-cathode LED, just use "constrain(color, 0, 255);"
red = 255 - constrain(red, 0, 255);
green = 255 - constrain(green, 0, 255);
blue = 255 - constrain(blue, 0, 255);
// fade the red, green, and blue legs of the LED:
analogWrite(redPin, red);
analogWrite(greenPin, green);
analogWrite(bluePin, blue);
// print the three numbers in one string as hexadecimal:
Serial.print(red, HEX);
Serial.print(green, HEX);
Serial.println(blue, HEX);
}
}
}
ASCII Table
void setup() {
//Initialize serial and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
}
// prints title with ending line break
Serial.println("ASCII Table ~ Character Map");
}
// first visible ASCIIcharacter '!' is number 33:
int thisByte = 33;
// you can also write ASCII characters in single quotes.
// for example. '!' is the same as 33, so you could also use this:
//int thisByte = '!';
void loop() {
// prints value unaltered, i.e. the raw binary version of the
// byte. The serial monitor interprets all bytes as
// ASCII, so 33, the first number, will show up as '!'
Serial.write(thisByte);
Serial.print(", dec: ");
// prints value as string as an ASCII-encoded decimal (base 10).
// Decimal is the default format for Serial.print() and Serial.println(),
// so no modifier is needed:
Serial.print(thisByte);
// But you can declare the modifier for decimal if you want to.
//this also works if you uncomment it:
// Serial.print(thisByte, DEC);
Serial.print(", hex: ");
// prints value as string in hexadecimal (base 16):
Serial.print(thisByte, HEX);
Serial.print(", oct: ");
// prints value as string in octal (base 8);
Serial.print(thisByte, OCT);
Serial.print(", bin: ");
// prints value as string in binary (base 2)
// also prints ending line break:
Serial.println(thisByte, BIN);
// if printed last visible character '~' or 126, stop:
if (thisByte == 126) { // you could also use if (thisByte == '~') {
// This loop loops forever and does nothing
while (true) {
continue;
}
}
// go on to the next character
thisByte++;
}
Serial Call Response
int firstSensor = 0; // first analog sensor
int secondSensor = 0; // second analog sensor
int thirdSensor = 0; // digital sensor
int inByte = 0; // incoming serial byte
void setup() {
// start serial port at 9600 bps:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
}
pinMode(2, INPUT); // digital sensor is on digital pin 2
establishContact(); // send a byte to establish contact until receiver responds
}
void loop() {
// if we get a valid byte, read analog ins:
if (Serial.available() > 0) {
// get incoming byte:
inByte = Serial.read();
// read first analog input, divide by 4 to make the range 0-255:
firstSensor = analogRead(A0) / 4;
// delay 10ms to let the ADC recover:
delay(10);
// read second analog input, divide by 4 to make the range 0-255:
secondSensor = analogRead(1) / 4;
// read switch, map it to 0 or 255L
thirdSensor = map(digitalRead(2), 0, 1, 0, 255);
// send sensor values:
Serial.write(firstSensor);
Serial.write(secondSensor);
Serial.write(thirdSensor);
}
}
void establishContact() {
while (Serial.available() <= 0) {
Serial.print('A'); // send a capital A
delay(300);
}
}
Serial Call Response ASCII
int firstSensor = 0; // first analog sensor
int secondSensor = 0; // second analog sensor
int thirdSensor = 0; // digital sensor
int inByte = 0; // incoming serial byte
void setup() {
// start serial port at 9600 bps and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
}
pinMode(2, INPUT); // digital sensor is on digital pin 2
establishContact(); // send a byte to establish contact until receiver responds
}
void loop() {
// if we get a valid byte, read analog ins:
if (Serial.available() > 0) {
// get incoming byte:
inByte = Serial.read();
// read first analog input:
firstSensor = analogRead(A0);
// read second analog input:
secondSensor = analogRead(A1);
// read switch, map it to 0 or 255L
thirdSensor = map(digitalRead(2), 0, 1, 0, 255);
// send sensor values:
Serial.print(firstSensor);
Serial.print(",");
Serial.print(secondSensor);
Serial.print(",");
Serial.println(thirdSensor);
}
}
void establishContact() {
while (Serial.available() <= 0) {
Serial.println("0,0,0"); // send an initial string
delay(300);
}
}
constrain
constrain(x, a, b)
Description
Constrains a number to be within a range.
Parameters
x: the number to constrain, all data types
a: the lower end of the range, all data types
b: the upper end of the range, all data types
Returns
x: if x is between a and b
a: if x is less than a
b: if x is greater than b
