matlab-connect-arduino

Set Up Arduino Board in MATLAB

Guides the agent through discovering, configuring, and connecting to Arduino boards via USB, ensuring the user is informed and in control at each step.

When to Use

• User wants to connect to an Arduino board from MATLAB
• User asks to discover or list connected Arduino boards
• User's task requires an Arduino connection as a prerequisite (reading sensors, controlling actuators, scanning I2C, etc.)
• User mentions Arduino, COM port, serial port, or hardware setup

When NOT to Use

• Creating custom addon libraries for unsupported peripherals (see matlab-create-custom-arduino-library)
• Bluetooth or WiFi Arduino connections (not covered here)
• Arduino IDE or support package installation issues
• Simulink hardware-in-the-loop workflows
• Tasks that already have an active arduino object in the workspace

Workflow

Follow these steps in order. Do not skip steps or guess values.

Core principle: Never assume. Always ask the user before proceeding if any information is unclear or ambiguous.

Step 1: Discover boards

Always run both commands — do not skip serialportlist even if arduinolist already found the board. This is a hard requirement:

list = arduinolist
ports = serialportlist("available")

Both calls are mandatory. Never omit serialportlist — arduinolist alone misses boards without support package firmware.

arduinolist returns a table with Port, Board, Status, and Libraries columns. However, it cannot list all connected boards as of R2026a — it may only show one even when multiple are connected. Always also run serialportlist("available") to catch all available ports.

If arduinolist is not available (pre-R2024a), skip it and rely on serialportlist("available") alone.

Present both results to the user.

Step 1b: Handle "no board detected"

If arduinolist returns an empty table AND serialportlist("available") shows no obvious Arduino ports (or all connection attempts fail), do not brute-force all ports. Instead:

1. Ask immediately: "No Arduino board was detected. Is the board physically connected via USB?"
2. Guide to OS tools: Present the appropriate guidance to the user based on their operating system:
   • Windows: "Open Device Manager → Ports (COM & LPT). Do you see a device labeled 'Arduino' or 'USB-SERIAL CH340' / 'USB Serial Device'? If not, the board may not be connected or needs a driver."
   • macOS: "Run ls /dev/cu.usb* in a terminal. Arduino boards typically appear as /dev/cu.usbmodem* or /dev/cu.usbserial*."
   • Linux: "Run dmesg | tail -20 after plugging in the board. Look for /dev/ttyACM* or /dev/ttyUSB*."
3. Suggest common fixes:
   • Try a different USB cable (some are charge-only, no data)
   • Try a different USB port
   • Install the board's USB driver (CH340 for clones, FTDI for others)
   • Ensure no other application (Arduino IDE Serial Monitor, PuTTY) holds the port open
   • If the board was manually disconnected without clearing the arduino object, restart MATLAB and reconnect
   • For detailed troubleshooting, refer the user to: https://www.mathworks.com/help/matlab/supportpkg/arduino-connection-failure.html
4. STOP and wait. Do not proceed to Step 2 or beyond until the user responds. If the user confirms the board is not connected, continue troubleshooting here. If connected, return to Step 1 and re-run discovery.

Step 2: Help user identify ports

Serial port names alone do not tell the user what device is connected. Guide the user to identify which ports are Arduino boards:

• Windows: "Check Device Manager (Ports section) to see which COM ports correspond to Arduino boards."
• macOS: "Look for /dev/cu.usbmodem* or /dev/cu.usbserial* entries — these are typically Arduino boards."
• Linux: "Check dmesg | grep tty or look for /dev/ttyACM* and /dev/ttyUSB* devices."

Step 3: Ask the user to select board

Present the discovered boards/ports and ask the user which to connect to. Never auto-select a board.

Ask for:

1. Port (required) — which COM port / device path
2. Board type (optional) — if the user doesn't know, use arduino('<port>') which auto-detects the board type

For multi-board scenarios, ask the user to identify each board by port and its intended role.

Step 4: Determine libraries

The default libraries are {'I2C', 'SPI', 'Servo'} — MATLAB loads these automatically if no Libraries argument is specified.

Library strategy:

1. Start with the defaults: {'I2C', 'SPI', 'Servo'}
2. Infer additional libraries from the user's prompt using this mapping:

User mentions	Add library
ultrasonic, distance sensor, HC-SR04	'Ultrasonic'
shift register, 74HC595	'ShiftRegister'
rotary encoder, quadrature	'RotaryEncoder'
motor shield, Adafruit motor	'Adafruit/MotorShieldV2'
motor carrier, MKR motor	'MotorCarrier'
CAN bus	'CAN'
serial device, UART	'Serial'
APDS9960, gesture, color sensor	'APDS9960'

Only infer from the table above when the match is explicit and unambiguous. If uncertain, ask the user rather than guessing libraries.

3. Tell the user which libraries you are including and why
4. Ask the user if any additional libraries are needed
5. If the user asks what's available, run listArduinoLibraries and show the full list

Step 5: Connect

Build the arduino() call based on what you gathered:

% TEMPLATE — not executable
% With board type known + custom libraries:
a = arduino('<port>', '<board>', 'Libraries', {'I2C', 'SPI', 'Servo', ...});

% With board type known, default libraries only:
a = arduino('<port>', '<board>');

% Auto-detect board type (uses libraries already flashed on board):
a = arduino('<port>');

Important: You cannot specify 'Libraries' without also specifying the board type. If the user doesn't know their board type but needs extra libraries, run arduino('<port>') first to auto-detect, then read a.Board and reconnect with the board type and libraries specified.

If the connection fails:

1. Stop immediately — do not retry automatically
2. Report the exact error message to the user
3. Provide 1–2 targeted fixes based on the error
4. Do not retry with different ports or board types unless the user explicitly instructs

Common issues:

• Port is busy (another application has it open)
• "Device in use" — an arduino object already exists in the workspace; the user must clear it before reconnecting
• Wrong board type specified
• Board needs a firmware reset (double-tap reset button)

Step 6: Confirm and hand off

After successful connection:

1. Confirm to the user: "Connection established to [Board] on [Port] with libraries: [list]."
2. If the user's prompt includes a task beyond just connecting (e.g., "blink LED", "read ultrasonic sensor"), announce: "Now proceeding with [task]..." and continue with the downstream workflow.

Key Functions

Function	Purpose	Available From
arduinolist	Discover connected Arduino boards (table output)	R2024a
serialportlist("available")	List all available serial ports	R2019b
arduino(port)	Connect with auto-detected board type, default libraries	R2014b
arduino(port, board)	Connect with specified board, default libraries	R2014b
arduino(port, board, 'Libraries', libs)	Connect with specified board and custom libraries	R2014b
listArduinoLibraries	List all available add-on libraries	R2014b

Patterns

Single board connection

% TEMPLATE — not executable
% Step 1: Discover
list = arduinolist;
ports = serialportlist("available");

% Step 3-5: Connect (after user selects port and board is known)
a = arduino('COM8', 'Nano33BLE', 'Libraries', {'I2C', 'SPI', 'Servo', 'Ultrasonic'});

Multi-board connection

% TEMPLATE — not executable
% Connect to each board with its own variable and libraries
a1 = arduino('COM8', 'Nano33BLE', 'Libraries', {'I2C', 'SPI', 'Servo'});
a2 = arduino('COM52', 'Uno', 'Libraries', {'I2C', 'SPI', 'Servo', 'Ultrasonic'});

Common Mistakes

Mistake	Why It's Wrong	Correct Approach
Using arduino() with no arguments	Connects to arbitrary board without user consent	Always discover first, let user choose
Guessing COM port or board type	Wastes time on wrong ports, reflashes wrong boards	Ask the user, or use auto-detect with port only
Loading only the needed library	Reconnecting later with more libraries takes 30+ sec	Load defaults {'I2C','SPI','Servo'} plus any inferred extras
Using arduino(port, 'Libraries', libs) without board	Error: must specify both port and board before name-value pairs	Use arduino(port, board, 'Libraries', libs) or arduino(port) for auto-detect with defaults
Skipping serialportlist when arduinolist succeeds	Misses boards without support package firmware or pre-R2024a boards	Always run both — serialportlist is mandatory even when arduinolist returns results
Killing processes to free a port	Destructive action without user consent	Report the port conflict, ask user to close the other application

Conventions

• MUST run both arduinolist AND serialportlist("available") in every discovery step — even if arduinolist already found the board. serialportlist catches boards that arduinolist does not recognize.
• Always present discovered information to the user before acting
• Board type is optional — let MATLAB auto-detect when user doesn't know
• Default libraries {'I2C', 'SPI', 'Servo'} are always included
• Never take destructive actions (killing processes, clearing workspaces) without asking
• Clearly separate the connection step from downstream task execution
• Arduino hardware is not shareable — only one MATLAB session can hold a connection to a given board at a time. Do not run multiple parallel agents that each try to connect to Arduino hardware. Run Arduino workflows sequentially.

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