rkdeveloptool "not found any devices!": Board Not Detected Over USB

Symptoms

rkdeveloptool ld prints "not found any devices!"
lsusb shows no 2207:xxxx device

Common causes

Board booted normally (from SD/eMMC) instead of entering MaskROM
Connected to a host-only USB port instead of the OTG port
Charge-only USB cable
On macOS/Windows: missing driver or USB permission

How to fix it

Confirm what the host sees

lsusb | grep 2207 || echo "no Rockchip device"

Force MaskROM
Remove the SD card, hold the MaskROM (or Recovery) button while applying power, release after ~2 s. On boards without a button, short the eMMC CLK test point to GND at power-on.
Use the OTG port and a data cable
The OTG port is usually a USB-C port marked OTG, or the upper USB 3 port on some SBCs; check the board docs.

Go deeper

What Is MaskROM Mode? Rockchip Recovery and Loader Mode Explained

FAQ

What does "not found any devices!" mean?

The host does not see any Rockchip device on USB, so the board is not in MaskROM/Loader mode or is not connected through the right port.

What causes "not found any devices!"?

Board booted normally (from SD/eMMC) instead of entering MaskROM; Connected to a host-only USB port instead of the OTG port; Charge-only USB cable; On macOS/Windows: missing driver or USB permission.

How do I fix "not found any devices!"?

1. Confirm what the host sees 2. Force MaskROM: Remove the SD card, hold the MaskROM (or Recovery) button while applying power, release after ~2 s. On boards without a button, short the eMMC CLK test point to GND at power-on. 3. Use the OTG port and a data cable: The OTG port is usually a USB-C port marked OTG, or the upper USB 3 port on some SBCs; check the board docs.