Debug Adapter
The Debug Adapter Board is designed to bridge the Qualcomm Snapdragon's debug interfaces as well as the system controller (MCU) interfaces. This allows for low-level debugging of the system, providing both hardware-level access and software debugging capabilities.
The Debug Adapter is a small PCB that includes:
- An FTDI serial-to-USB chip for 1.8V to USB translation
- A CMSIS-DAP (aka CMDAP) interface for programming the built-in microcontroller
⚠️ Note: The system controller is not yet user-accessible, but we may expose more functionality as the software stabilizes. Bricking the board is possible if the system controller is incorrectly modified. Be cautious!
Hardware Overview
Top View
Bottom View
Schematic
Hardware Features
| Label | Description |
|---|---|
| 1 | USB-C Connector |
| 2 | Segger J-Link Debugger Connector |
| 3 | UART1 (MCU Debug) |
| 4 | UART1 Activity LEDs |
| 5 | Debugging Connection to Tachyon |
| 6 | UART2 Activity LEDs |
| 7 | UART2 (Linux Console) |
| 8 | Power LED |
💡 Note: The RX/TX LEDs indicate traffic activity, with the green power LED showing that the board is active.
Working with the Debug Adapter
FTDI Serial-to-USB Support
The FTDI chip used in the Debug Adapter Board is natively supported on most modern operating systems:
✅ Mac → No driver installation needed
✅ Linux → Plug-and-play support
✅ Windows → May require FTDI drivers from FTDI’s official website
🔌 Connecting the Debug Adapter
1/ Plug the Debug Adapter into Tachyon
2/ Connect the USB-C cable to your computer
Once connected, two serial ports (TTY devices) will appear on your system.
Example Serial Ports on macOS
ls /dev/tty.usbserial-*
/dev/tty.usbserial-0000590
/dev/tty.usbserial-0000591
These correspond to:
Port 0 → System Controller (MCU) Debug Output Port 1 → Linux Console (Bootloader + Kernel Logs)
Both ports use: • Baud Rate: 115200 • Flow Control: None
🖧 Using the Serial Ports
System Controller Debug Console (Port 0) • Provides interactive access to the MCU • Runs manufacturing test commands • Used to debug low-level module operations
Example: Opening the System Controller Console with Minicom
minicom -D /dev/tty.usbserial-0000590 -b 115200
🖥️ Linux Console (Port 1 - Root Console) • Shows bootloader logs (UEFI + Kernel) • Displays low-level system logs • Useful for debugging boot issues, crashes, or kernel modifications
Example: Viewing the Linux Console Logs
minicom -D /dev/tty.usbserial-0000591 -b 115200
You can also use screen if you wish!
screen /dev/tty.usbserial-0000591 115200
Why Use It?
If your device fails to boot, you can use this root console to diagnose errors and recover from firmware changes.
⚠️ Important Debug Board Notes
- 🚫 The Debug Adapter does NOT provide power to Tachyon.
- 🛑 The board includes a buffer chip to prevent leakage, ensuring that Tachyon can fully power off when disconnected.
- EVT kits come with a Debug Adapter, but this will also be sold as an optional extra for general use.