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MCP Server for Segger RTT via J-Link

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MCP Server for Segger RTT via J-Link

An MCP server that provides access to Segger RTT (Real Time Transfer) through a J-Link debugger. This allows an LLM (like Claude) to interact with embedded devices by reading and writing RTT data.

Features

  • RTT Read: Read output from embedded devices through RTT up-buffer

  • RTT Write: Send commands to embedded devices through RTT down-buffer

  • J-Link Management: Connect/disconnect J-Link debuggers, list available devices

  • Real-time Display: RTT data is continuously printed to terminal while monitoring

  • Ring Buffer: Recent RTT data is accumulated for reading by the LLM

Related MCP server: MCP Serial Port Tool

Prerequisites

  • Python 3.10+

  • SEGGER J-Link Software installed (provides JLinkARM.dll/libjlinkarm.so)

  • A J-Link compatible debugger

  • Target device running SEGGER RTT

Installation

# Clone or navigate to this directory
cd mcp-rtt-server

# Install dependencies
pip install -e .

Usage

Step 1: 安装

cd mcp-rtt-server
pip install -e .

Step 2: 启动 MCP Inspector（调试/测试用）

终端 A — 启动 MCP 服务器：

npx @modelcontextprotocol/inspector python -m mcp_rtt_server.server

启动后会输出一个本地网址（如 http://localhost:6274/?...），在浏览器打开。

终端 B — 实时查看 RTT 数据：

# PowerShell
Get-Content .\rtt_output.log -Wait
# Git Bash / WSL
tail -f ./rtt_output.log

Step 3: 使用工具

在浏览器 Inspector 中按顺序调用：

  1. jlink_connect — 连接 J-Link 和目标设备，启动 RTT 监控

  2. rtt_read — 读取设备发送的 RTT 数据

  3. rtt_write — 向设备发送数据（需固件支持接收）

  4. jlink_status — 查看连接状态和缓冲区信息

  5. jlink_disconnect — 断开连接

Claude Code 集成

在项目 .claude/settings.json 中添加：

{
  "mcpServers": {
    "rtt": {
      "command": "python",
      "args": ["-m", "mcp_rtt_server.server"],
      "cwd": "."
    }
  }
}

注意：将 python 替换为你的 Python 解释器实际路径（如 C:\Python313\python.exe）。

重启 Claude Code 会话后，可直接用自然语言与设备交互，例如：

  • "连接 RTT 读取设备数据"

  • "查看设备状态"

Claude Desktop 集成

编辑 %APPDATA%\Claude\claude_desktop_config.json：

{
  "mcpServers": {
    "rtt": {
      "command": "python",
      "args": ["-m", "mcp_rtt_server.server"],
      "cwd": "."
    }
  }
}

注意：cwd 需要改为本项目的实际绝对路径，因为 Claude Desktop 不会自动定位到项目目录。

Available Tools

Tool

Description

jlink_connect

Connect to J-Link and start RTT monitoring

jlink_disconnect

Disconnect from J-Link

jlink_status

Get connection status and buffer info

rtt_list_devices

List available J-Link devices

rtt_read

Read accumulated RTT data

rtt_write

Write data to RTT down-buffer

rtt_clear

Clear the RTT ring buffer

Example Session

> jlink_connect(device="HC32L19x")
Connected to J-Link device 'HC32L19x' (serial: 12345678, speed: 4000 kHz)
RTT monitoring started on channel 0

> rtt_read()
[OSAL] HC32L19x OSAL starting...
[RTT] SEGGER RTT initialized
[OSAL] Registering tasks...
[OSAL] Starting scheduler...

> rtt_write(channel=0, data="status\r\n")
Wrote 7 bytes to RTT channel 0

Architecture

┌─────────────────┐     stdio (JSON-RPC)     ┌─────────────────┐
│   Claude /      │ ◄──────────────────────►  │  MCP RTT Server │
│   MCP Client    │                          │    (Python)     │
└─────────────────┘                          └────────┬────────┘
                                                      │
                                             pylink   │
                                                      ▼
                                            ┌─────────────────┐
                                            │  JLinkARM.dll   │
                                            └────────┬────────┘
                                                      │ USB
                                                      ▼
                                            ┌─────────────────┐
                                            │   J-Link Probe  │
                                            └────────┬────────┘
                                                      │ SWD/JTAG
                                                      ▼
                                            ┌─────────────────┐
                                            │  Target Device  │
                                            │  (HC32L19x)     │
                                            │  SEGGER RTT     │
                                            └─────────────────┘

Environment Variables

Variable

Default

Description

JLINK_SERIAL

(none)

J-Link serial number

JLINK_DEVICE

HC32L19x

Target device name

JLINK_SPEED

4000

SWD speed in kHz

RTT_CHANNEL

0

Default RTT channel

RTT_RING_BUFFER_SIZE

100

Ring buffer entries

RTT_POLL_INTERVAL_MS

10

Poll interval in ms

Troubleshooting

"J-Link not found"

  • Make sure J-Link software is installed

  • Check that J-Link is connected via USB

  • Try running as administrator/root

"Device not supported"

  • Check if the device name is correct

  • Try using rtt_list_devices to see available probes

  • Verify the target is connected and powered

"RTT not initialized"

  • Make sure the target firmware calls SEGGER_RTT_Init()

  • Check that RTT buffers are configured in SEGGER_RTT_Conf.h

License

MIT

This server cannot be installed

A
license - permissive license
-
quality - not tested
D
maintenance

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Maintenance

–Maintainers
–Response time
–Release cycle
–Releases (12mo)
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