ruiwarn MCU RTT Debugger
Automated MCU debugging skill using SEGGER J-Link RTT. Enables headless log collection, analysis, and AI-driven feedback without GUI dependencies.
Prerequisites
- J-Link Software: JLinkRTTLogger must be installed and in PATH
- Hardware: J-Link debugger connected via SWD/JTAG
- Firmware: Target MCU must have RTT initialized (SEGGER_RTT)
Verify installation:
which JLinkRTTLogger || echo "JLinkRTTLogger not found in PATH"
Quick Start
1. Start RTT Log Collection
python scripts/rtt_control.py start \
--device STM32F103C8 \
--speed 4000 \
--channel 0 \
--output /tmp/rtt_latest.log
2. Wait and Collect Logs
# Run for 30 seconds, then stop
python scripts/rtt_control.py start --device STM32F103C8 --duration 30
3. Analyze Logs
python scripts/analyze_log.py /tmp/rtt_latest.log
Available Scripts
scripts/rtt_control.py
RTT log collection control. Run with --help for full options.
Key Commands:
start- Start RTT log collectionstop- Stop running RTT sessionstatus- Check if RTT is running
Parameters:
| Parameter | Description | Default |
|---|---|---|
--device |
MCU device name (e.g., STM32F103C8) | Required |
--interface |
Debug interface (SWD/JTAG) | SWD |
--speed |
SWD clock speed in kHz | 4000 |
--channel |
RTT Up Channel number | 0 |
--output |
Log output file path | /tmp/rtt_latest.log |
--duration |
Auto-stop after N seconds | None (manual) |
--background |
Run in background mode | False |
scripts/analyze_log.py
Log analysis and AI feedback generation. Run with --help for full options.
Key Options:
--last-seconds N- Analyze only last N seconds--last-lines N- Analyze only last N lines--format json|text- Output format--summary- Generate executive summary only
Typical Workflow
When user says: "Start online debugging for 30 seconds, check if code runs correctly"
Execute this workflow:
Start RTT collection in background
python scripts/rtt_control.py start \ --device <MCU_DEVICE> \ --duration 30 \ --backgroundWait for collection to complete (or manually stop early)
Analyze collected logs
python scripts/analyze_log.py /tmp/rtt_latest.log --summaryReport findings with structured conclusion:
- Runtime status: PASS / FAIL / UNSTABLE
- Error summary (if any)
- Debugging recommendations
Log Format Convention
For optimal AI analysis, firmware should follow the structured log format. See references/log_format.md for detailed specification.
Required Prefixes:
[BOOT]- Boot/initialization messages[STAT]- Status/statistics[TEST]- Test results[ERR]- Errors[ASSERT]- Assertion failures[FAULT]- HardFault/system faults
Recommended Key-Value Format:
[TEST] name=spi_dma result=pass
[ERR] type=i2c_nack addr=0x68
[STAT] loop_hz=998 heap_free=4096
Error Handling
| Scenario | Script Behavior |
|---|---|
| J-Link not connected | Exit with clear error message |
| MCU not responding | Retry 3 times, then report failure |
| RTT not initialized | Report "RTT control block not found" |
| MCU reset during logging | Attempt to re-attach automatically |
Analysis Output Example
{
"status": "FAIL",
"duration_seconds": 30,
"summary": {
"boot_detected": true,
"tests_run": 5,
"tests_passed": 4,
"tests_failed": 1,
"errors_count": 2,
"faults_detected": false
},
"errors": [
{"type": "i2c_nack", "addr": "0x68", "count": 2, "first_seen": "00:15.234"}
],
"failed_tests": [
{"name": "i2c_sensor_read", "reason": "timeout"}
],
"recommendation": "I2C communication failure detected. Check I2C bus connections and pull-up resistors. Verify device at address 0x68 is powered and responding."
}
Extending This Skill
Future enhancements (not in current scope):
- Auto flash firmware before debugging
- Multi-channel RTT support
- CI/HIL test integration
- Automated reset/retry cycles