{"id":946,"date":"2018-08-06T21:06:34","date_gmt":"2018-08-06T19:06:34","guid":{"rendered":"https:\/\/www.nerdiy.de\/?p=946"},"modified":"2020-05-02T12:08:02","modified_gmt":"2020-05-02T10:08:02","slug":"ardunio-the-serial-interface","status":"publish","type":"post","link":"https:\/\/nerdiy.de\/en\/ardunio-the-serial-interface\/","title":{"rendered":"HowTo: Ardunio \u2013 Use the serial port"},"content":{"rendered":"

Normally every Arduino board is programmed via the serial interface.
\nBut not only the program code can be transferred to the Arduino. You can also send control commands to the Arduino or receive values from the Arduino.<\/p>\n

How to do this and what options you have I describe in the following article.<\/p>\n

\n

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\n

Prepare serial interface<\/h2>\n

To use the serial port in your program you have to initialize it.
\nThis is done by calling in the \"setup()\" function the function<\/p>\n

Serial.begin(115200);<\/pre>\n
is called. The number \"115200\" stands for the baud rate - i.e. the speed - with which the symbols (not bits or bytes) are transmitted via the serial interface. You should make this speed dependent on the \"quality\" of the connection line.<\/p>\n
For example, if you have a shielded and very short cable, the speed can be set very high.
\nFor unshielded and\/or very long cables, this speed should not be set so high.<\/p>\n
Common baud rates are for example the following values:<\/p>\n
50\r\n110\r\n150\r\n300\r\n1200\r\n2400\r\n4800\r\n9600\r\n19200\r\n38400\r\n57600\r\n115200\r\n230400\r\n460800\r\n500000<\/pre>\n
No matter which speed you set, this value must also be set in the \"Serial Monitor\" - i.e. the other communication partner of the serial communication. Only then the characters are received and sent correctly. You will learn more about this in the course of the text.<\/p>\n
If you are unsure which baud rate to use I recommend values between 9600 baud and 115200 baud. These and the values in between are also the common values for many finished products like sensors and actuators.<\/p>\n
\n
Send data from the Arduino board to the connected computer<\/h2>\n
To send data from your Arduino board to the connected computer you have to call the following function.<\/p>\n
This sends the text \"Hello world!\" including line break to the computer.<\/p>\n
Serial.println("Hello world!");<\/pre>\n
As an example you can try the following code.<\/p>\n
void setup() { Serial.begin(115200); } void loop() { Serial.println("Hello world!"); delay(1000); }<\/pre>\n
\"\"<\/a>
This will give you the output shown. After each \"Hello world!\" a change to the next line is made automatically.<\/figcaption><\/figure>\n
In the following combination, the function sends the text \"Hello world!\" to the computer without a line break.<\/p>\n
Serial.print("Hello world!");<\/pre>\n
There is another example of this.<\/p>\n
void setup() { Serial.begin(115200); } void loop() { Serial.print("Hello world!"); delay(1000); }<\/pre>\n
\"\"<\/a>
Since there is no line break after the \"Hello World!\", a long line is created from several \"Hello World!\" sections.<\/figcaption><\/figure>\n
If you want to send variable values - in this case the value of the variable \"funny_variable\" - you can do this as follows:<\/p>\n
uint8_t funny_variable=5; Serial.println(String(funny_variable));<\/pre>\n
As an example, the whole thing looks like this again.<\/p>\n
void setup() { Serial.begin(115200); } void loop() { uint8_t funny_variable=5; Serial.println(String(funny_variable)); delay(1000); }<\/pre>\n
\"\"<\/a>
The value (5) of the variable is output including line break.<\/figcaption><\/figure>\n
Sending a line break means that in addition to the actual message content, a control character is also sent that signals the recipient to change to the next line.<\/p>\n
\n
Use serial monitor<\/h2>\n
The Serial Monitor is the counterpart to the Arduino board. It is the program which receives the data from the computer and makes it readable for you.
\nYou can find it as part of the Arduino IDE under the menu item \"Tools\/Serial Monitor\". Tools like this \"Serial Monitor\" are also called terminal programs. A good alternative to the \"Serial Monitor\" of the Arduino IDE is also the program HTERM.<\/a><\/strong><\/em><\/p>\n
\"\"<\/a>
In the Serial Monitor window the line terminator and the baud rate can be set. By clicking on \"Clear output\" the content of the output window can also be cleared.<\/figcaption><\/figure>\n
In the window of the serial monitor you can set the baud rate. Here you have to set the same value that you have set before in the program code.
\nIf you have used the command<\/p>\n
Serial.begin(115200);<\/pre>\n
so you have to set a baudrate of 115200 baud in the serial monitor.<\/p>\n
Besides the baud rate you can also set the line terminator. You only need this setting if you want to send data from the computer to the Arduino.<\/p>\n
Here you can set the character that is automatically appended and sent after each value is sent.<\/p>\n
You can use this in your code for example to detect on the Arduino if the transmission of a command or value is completed.<\/p>\n
In the section \"Sending commands and parameters to the Arduino\" this is explained in detail.<\/p>\n
\n
Use serial plotter<\/h2>\n
The serial plotter is a tool with which you can display numerical values (e.g. measured values) directly on the computer as a time curve. To do this, you must program the Arduino so that it sends the numerical values to the computer.
\nThis can be done, for example, with the command:<\/p>\n
Serial.println(VariableWithAReading);<\/pre>\n
The variable \"VariableWithAMeasuredValue\" should of course contain your measured value as a number.
\nOn the computer you have to start the serial plotter. You can find it under \"Tools\/Serial Plotter\".<\/p>\n
A simple example that outputs a sine curve on the serial plotter is the following. Just try the code. It should run on any Arduino. Remember to set your serial plotter to 115200 baud.<\/p>\n
\/* _ _ _ _ _\r\n                                 | | | | |(_) | |\r\n  __ ____ ____ __ | | | ___ _ __ __| | _ _ _ __| | ___\r\n    \/ \/ \/ \/ \/ \/ \/ \/ \/ | . ` | \/ _ | '__|\/ _` || || | | | \/ _` | \/ _\r\n    V V \/ V V \/ V \/_ | | || __\/| | (_| || |_| | _| (_| || __\/\r\n    \\_\/\\_\/ \\_\/\\_\/ \\_\/\\_\/(_)|_| \\_| \\___||_| \\__,_||_| \\__, |(_)\\__,_| \\___|\r\n                                                               __\/ |\r\n                                                              |___\/\r\n     sinusTest by Fabian Steppat\r\n     Info on https:\/\/www.nerdiy.de\/ardunio-die-serielle-schnittstelle\/\r\n\r\n     This program is free software: you can redistribute it and\/or modify\r\n     it under the terms of the GNU General Public License as published by\r\n     the Free Software Foundation, either version 3 of the License, or\r\n     (at your option) any later version.\r\n\r\n     This program is distributed in the hope that it will be useful,\r\n     but WITHOUT ANY WARRANTY; without even the implied warranty of\r\n     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\r\n     GNU General Public License for more details.\r\n\r\n     You should have received a copy of the GNU General Public License\r\n     along with this program.  If not, see .\r\n\r\n     You will find additional information to this project at the following address:\r\n     
HowTo: Ardunio \u2013 Use the serial port<\/a><\/blockquote>