LE6 serial input arduino read Bytes Until 2021 PDF

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Universidad Tecnológica de Tijuana Tecnologías de Información

Lab experiment 6 Reading the Serial buffer using a readBytesUntil OBJECTIVE The student will get to know how acquire incoming Serial data into a char array searching for a terminating character. Practice materials:   

Arduino UNO USB cable PC or Laptop with the Arduino C++ IDE installed

Serial.readBytesUntil()- This function reads the Arduino’s incoming serial buffer characters into a character array. The function ends if the given terminating character is detected, or if the maximum length has been read or if the configured timeout expires. The function returns the number of characters in the incoming Serial buffer. If it returns a number 0, it means that no valid data was found.

Sintaxis Serial.readBytesUntil(terminating_character, buffer_array, length)

Parameters: terminating_character: Character to search for, any will do, usually ‘\n’ or ‘\r’. Some

protocols use special characters like ‘@’ or uncommon characters like ‘#’ or ‘&’. bufer_array (char) : Char buffer that will store the incoming Serial bytes Lenght : Number of byte to read (int)

Assigment: 1. Analyze and then type in the Arduino IDE sketch listed at the end of this assignment, name it anything, a suggestion would be LE6_readBytesUntil. 2. Be sure that the Serial Monitor is in “Carriage Return” mode and correct baud rate, which is chosen in the lower right corner of the Serial Monitor, as shown in the Electrónica para IdC

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Universidad Tecnológica de Tijuana Tecnologías de Información

following figure. This means that any message you send to the Arduino the Serial Monitor program will add a carriage return character ‘\r’ at the end of the message as an end of line (EOL) character.

Fig. 1. Serial Monitor, “Carriage return” option.

3. At the start, the program will ask your name and will wait for your answer. Type your “matricula” instead, and send. Print screen.

4. Now, test sending words. Print screen. 5. Type more than 20 characters. Print screen.

Research questions 6. What happens when the message exceeds the 20 character length? 7. How could you avoid messages getting cut in pieces?

ARDUINO CODE The following sketch uses a 20 character array to store the message received at the Arduino’s serial port, it uses the readBytesUntil( ) function. It works even if the messages do not have the String termination, new line or carriage return. This is because the readBytesUntil( ) function always returns if it exceeds a 1 second timeout.

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