FDL Mode

How to enter devices into FDL mode — steps for popular brands and models.

FDL mode (Firmware Downloader mode) in Spreadtrum (SPD) / Unisoc CPUs is a specialized low-level boot state used for flashing, servicing, or backing up firmware on Android devices and feature phones. It is often referred to as "Spreadtrum Boot Block" mode, which enables communication between the phone and a PC tool (like SPD Research Tool) to read/write flash memory before the Android operating system loads.

GitHub +2

Key Aspects of FDL Mode:

  • Two-Stage Process: FDL is typically split into two stages, FDL1 and FDL2.

    • FDL1: Initializes the external RAM.

    • FDL2: Loads into RAM to perform the actual writing/reading of the flash memory.

  • Functionality: This mode is crucial for unbricking phones, removing user locks, upgrading firmware, or dumping existing firmware files.

  • Accessing the Mode: Devices are typically placed into FDL mode by powering them off and connecting them via USB while holding a boot key, often the Volume Down key.

  • Tools: The mode is used with tools like DFTPro ,EFTPro , UnlockTool , Chimera and many others!