What Is ISP Pinout

ISP (In-System Programming) is a hardware-level access method that allows technicians to communicate directly with a device's eMMC or UFS storage chip through dedicated test pads on the motherboard, bypassing the main CPU and Android OS entirely. On the Samsung SM-A336B (Galaxy A33 5G), ISP access is essential when the device cannot boot, is locked at the bootloader, or has suffered a failed firmware flash. By connecting a compatible tool directly to the ISP test points, technicians can read, write, or erase storage content at the chip level — enabling FRP removal, dead boot repair, and full firmware restoration without needing to desolder the storage chip.

SM-A336B ISP Test Points

The SM-A336B uses a UFS 2.2 storage interface, and the ISP test pads are located on the back side of the main motherboard near the UFS package. The primary pads required for ISP access are listed below. Coordinates are approximate and should be confirmed visually using a high-resolution board schematic or known-good reference image before probing.

  • CLK — UFS clock signal pad; provides the reference clock for data transfer
  • DATA0 (DQ0) — Primary data line for UFS communication
  • DATA1 (DQ1) — Secondary data line
  • VCC — Main storage power supply (2.9V–3.0V); used to power the UFS die
  • VCCQ — I/O voltage rail (1.8V); powers the UFS interface logic
  • GND — Common ground reference; multiple ground pads available near the UFS footprint
  • RST — Reset line; used by some tools to initialize the UFS device

Exact pad labels and physical coordinates should be verified against a Samsung SM-A336B board map or a trusted ISP reference image prior to connection.

When Technicians Use ISP

ISP is the preferred repair method in several critical scenarios: the device is completely dead and does not respond to USB or power; standard Odin or Download Mode is inaccessible due to a corrupted bootloader; FRP (Factory Reset Protection) persists after a factory reset and cannot be cleared through software tools; or the device bootloops continuously after a failed OTA or manual firmware update. ISP bypasses all software-level locks, making it indispensable for these situations.

How to Access the Pinout

Follow these steps carefully to connect to the SM-A336B ISP test points:

  • Power off the device completely and disconnect the battery.
  • Remove the motherboard from the chassis following standard disassembly procedure.
  • Locate the UFS test pad cluster on the back side of the board using a schematic or reference image.
  • Clean the pad area with IPA and a soft brush to remove flux or contamination.
  • Attach fine-gauge ISP cables or probes from your tool to CLK, DATA0, DATA1, VCC, VCCQ, GND, and RST.
  • Connect your ISP tool (e.g., EasyJTAG Plus or UMT) to your PC and launch the appropriate software.
  • Select the UFS chip and SM-A336B profile, then apply voltage and initiate the desired operation.

Safety Tips and Warnings

Always work on an ESD-safe mat and wear an anti-static wrist strap — UFS dies are extremely sensitive to electrostatic discharge. Never apply voltage before confirming all probe connections are correct; reversed or floating lines can permanently damage the UFS chip. Verify VCCQ does not exceed 1.8V and VCC does not exceed 3.0V. Use fine-tip probes to avoid bridging adjacent pads. Do not attempt ISP repair without a confirmed schematic reference, as pad misidentification is a leading cause of board damage on this model.

Pin / Test Point Reference

PinDescription
CLKUFS clock signal test pad — Required for all ISP operations
DAT0Primary UFS data line (DQ0) — Main data transfer line
DAT1Secondary UFS data line (DQ1) — Required for UFS protocol
VCCUFS main power supply pad (~2.9–3.0V) — Do not exceed 3.0V
VCCQUFS I/O voltage pad (1.8V) — Powers interface logic; do not exceed 1.8V
GNDGround reference pad — Multiple GND points available near UFS
RSTUFS reset line — Used by some tools for chip initialization

Tools required: EasyJTAG Plus, UMT (Ultimate Multi Tool), Medusa Pro II, Hydra Tool, RIFF Box 2

Supported operations: Read Firmware, Write Firmware, FRP Erase, Dead Boot Repair, Full eMMC/UFS Backup, Bootloader Repair

⚠ Safety note: VCCQ must not exceed 1.8V; VCC must not exceed 3.0V. Use ESD precautions. Confirm pad locations against a verified schematic before applying power. Incorrect probing can permanently destroy the UFS chip.