Arduino Serial Monitor

Arduino Serial Monitor

This skill provides advanced tools for reading and analyzing serial monitor data from Arduino boards, enhancing the debugging experience beyond the basic Arduino IDE serial monitor.

Features

• Real-time Serial Monitoring: Connect to Arduino serial ports and display data in real-time
• Data Logging: Save serial output to files with timestamps for later analysis
• Filtering & Pattern Matching: Filter output by keywords, regex patterns, or data types
• Error Detection: Automatically highlight common error patterns and warnings
• Multiple Format Support: Handle different data formats (text, JSON, CSV, binary)
• Cross-platform: Works with Windows, macOS, and Linux serial ports

Structured Debugging Workflow

1. Record the exact board/revision, firmware/image identifier, toolchain and versions, port, baud, reset cause if known, and timestamp source.
2. Prefer one line per event with stable fields such as t_ms=123 level=INFO event=sensor_read value=...; keep secrets and tokens out of output.
3. Capture the unfiltered log before filtering. Preserve the first boot lines, reset/brownout/watchdog messages, and the transition that reproduces the symptom.
4. Label conclusions as build, upload, hardware, system, or deployment evidence. Report the result by proof stages. A clean serial stream is not proof that pins, power, or the full system are correct.
5. Pair with hardware-tdd for a test matrix and embedded-project-loop when the next observation must come from a user-operated board.

Recommended C++ Event Format

Serial.print("t_ms=");
Serial.print(millis());
Serial.print(" level=INFO event=ready board=");
Serial.println(BOARD_ID);

Use a fixed, bounded format appropriate to the board's memory budget. Do not log Wi-Fi passwords, API keys, certificates, tokens, or private data.

Usage

Basic Serial Monitoring

# Monitor serial port with default settings (9600 baud)
uv run --no-project scripts/monitor_serial.py --port COM3

# Specify baud rate and output file
uv run --no-project scripts/monitor_serial.py --port /dev/ttyACM0 --baud 115200 --output debug.log

# Filter for specific patterns
uv run --no-project scripts/monitor_serial.py --port COM3 --filter "ERROR|WARNING"

Advanced Debugging

# Parse JSON data from serial
uv run --no-project scripts/monitor_serial.py --port COM3 --format json --pretty

# Monitor with timestamp and color coding
uv run --no-project scripts/monitor_serial.py --port COM3 --timestamp --color

# Detect common Arduino errors
uv run --no-project scripts/monitor_serial.py --port COM3 --detect-errors

Script Options

• --port: Serial port (e.g., COM3, /dev/ttyACM0)
• --baud: Baud rate (default: 9600)
• --output: Output file for logging
• --filter: Regex pattern to filter lines
• --format: Data format (text, json, csv, binary)
• --timestamp: Add timestamps to output
• --color: Enable color-coded output
• --detect-errors: Highlight common error patterns
• --timeout: Connection timeout in seconds

Common Arduino Debugging Scenarios

Memory Issues

Filter for: "low memory|stack overflow|heap"

Sensor Data Validation

Filter for: "sensor|reading|value"
Format as: json

Timing Analysis

Enable: --timestamp
Filter for: "start|end|duration"

Communication Errors

Filter for: "timeout|failed|error"
Enable: --detect-errors

Integration with Arduino CLI

# Compile and upload, then monitor
arduino-cli compile --fqbn arduino:avr:uno sketch/
arduino-cli upload -p COM3 --fqbn arduino:avr:uno sketch/
uv run --no-project scripts/monitor_serial.py --port COM3

Troubleshooting

Port Not Found

• Check arduino-cli board list for available ports
• Ensure Arduino is connected and drivers are installed
• Try different port names (COM1-COM99 on Windows, /dev/ttyACM* on Linux)

No Data Received

• Verify baud rate matches Arduino sketch (Serial.begin(9600))
• Check USB cable connection
• Reset Arduino board while monitoring

Permission Errors (Linux/macOS)

# Add user to dialout group
sudo usermod -a -G dialout $USER
# Logout and login again

Evidence And Privacy

Record the board, firmware/image version, toolchain, baud, port, reset cause, and timestamp source. Label serial output as hardware or system evidence only when it was captured on the target. Redact Wi-Fi passwords, API keys, certificates, tokens, and personal data before saving logs or sharing them.

Dependencies

• Python 3.8+
• uv 0.4+ (the script declares pyserial and colorama inline)
• Run the self-contained helper with uv run --no-project scripts/monitor_serial.py --help.

Examples

Basic Temperature Sensor Monitoring

// Arduino sketch
void setup() {
  Serial.begin(9600);
}

void loop() {
  float temp = analogRead(A0) * 0.488;
  Serial.print("Temperature: ");
  Serial.print(temp);
  Serial.println(" C");
  delay(1000);
}

uv run --no-project scripts/monitor_serial.py --port COM3 --filter "Temperature" --timestamp

JSON Data Parsing

// Arduino sketch with JSON output
#include <ArduinoJson.h>

void setup() {
  Serial.begin(115200);
}

void loop() {
  StaticJsonDocument<200> doc;
  doc["temperature"] = analogRead(A0) * 0.488;
  doc["humidity"] = analogRead(A1) * 0.146;
  doc["timestamp"] = millis();
  serializeJson(doc, Serial);
  Serial.println();
  delay(2000);
}

uv run --no-project scripts/monitor_serial.py --port COM3 --format json --pretty

Shared Output Contract

Use the shared Arduino skill contract: state assumptions, required tools and versions, implementation steps, tests/evidence by proof stage, known limitations, and recovery/security notes.