pyserial library usage in Raspberry Pi - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the pyserial library?

The pyserial library allows Python programs to communicate with serial ports, such as those used by devices connected to a Raspberry Pi via USB or GPIO pins.

beginner

How do you open a serial port using pyserial?

You create a <code>Serial</code> object with the port name and baud rate, for example: <br><code>import serial<br>ser = serial.Serial('/dev/ttyUSB0', 9600)</code>

beginner

What method do you use to read data from a serial port in pyserial?

You can use ser.read(size) to read a specific number of bytes or ser.readline() to read until a newline character.

beginner

How do you write data to a serial port using pyserial?

Use the ser.write(data) method, where data is a bytes object. For example: ser.write(b'Hello') sends the string 'Hello'.

beginner

Why is it important to close the serial port after use?

Closing the serial port with ser.close() frees the resource so other programs or processes can use it and prevents errors or conflicts.

Which pyserial method reads a line of text from the serial port?

A read()

B open()

C write()

D readline()

The readline() method reads bytes until it encounters a newline character.

How do you specify the baud rate when opening a serial port with pyserial?

A As a parameter in Serial(), e.g., Serial('/dev/ttyUSB0', 9600)

B By calling ser.set_baudrate(9600)

C By setting an environment variable

D Baud rate is fixed and cannot be changed

The baud rate is set as the second argument when creating the Serial object.

What data type must you use when writing data with ser.write()?

A integer

B string

C bytes

D list

The write() method requires a bytes object, so strings must be encoded first.

What happens if you try to open a serial port that is already in use?

A The port resets automatically

B An exception is raised

C The program silently ignores it

D The port opens normally

Trying to open a busy port raises a serial.SerialException.

Which of these is a common serial port name on Raspberry Pi for USB serial devices?

A /dev/ttyUSB0

B /dev/serial0

C /dev/ttyS0

D /dev/null

/dev/ttyUSB0 is typically the first USB serial device connected.

Explain how to set up and use the pyserial library to read data from a serial device on a Raspberry Pi.

Think about opening the port, reading, and closing it.

Describe the steps to send a message to a device connected via serial port using pyserial.

Remember that write() needs bytes, not strings.