• JTAG/SWD
  • Advanced
  • 5 min
  • Serial CLI

Recipe · Advanced · JTAG/SWD

How to use an OpenOCD JTAG adapter

After SWD/JTAG pins are known, the firmware can switch into an OpenOCD adapter workflow. This recipe is the bridge between discovery and a real debug session.

OpenOCD debug adapter connection.
Do discovery first; adapter mode expects a known pinout and a supported host workflow.

Wiring View

BP SWD/JTAGBP GPIOsGNDBP GNDVREFcheck only
Generated from the wiring summary: to BP.
Step 1

Commands

Run the commands below after selecting the right Bit Pirate mode and confirming the wiring.

Result

What success looks like

The host sees the expected adapter interface and OpenOCD can attempt target detection. If the target fails, return to pinout/power checks first.

Troubleshooting

  • Pinout not actually verified.
  • Wrong OpenOCD config for the target.
  • Target held in reset or low-power state.
  • USB/CDC adapter mode not re-enumerated as expected.

Next steps

  • Use the scan recipes to verify SWD/JTAG pins.
  • Keep a known-good OpenOCD config beside the project.
  • Document target voltage, reset and boot strap requirements.

OpenOCD JTAG/SWD adapter FAQ

Should I scan pins before OpenOCD?

Yes. OpenOCD adapter mode expects a known JTAG or SWD mapping. Use the scan recipes first when the target pads are not labelled or not trusted.

What role does Bit Pirate play in an OpenOCD session?

Bit Pirate acts as the USB-facing transport adapter. OpenOCD still provides the target configuration, reset strategy and debug protocol logic for the MCU or SoC you are investigating.

Is Bit Pirate a replacement for a high-speed debug probe?

No. The USB adapter is useful for bring-up, recovery, experiments and low-speed debug access, but dedicated JTAG/SWD probes are better for production flashing and heavy debug sessions.

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