What Is ISP Pinout

ISP (In-System Programming) is a direct hardware method that allows technicians to communicate with a device's NAND flash storage — in this case UFS memory — by bypassing the main CPU boot process entirely. Rather than relying on the device to power on and enumerate over USB, ISP establishes a connection through dedicated test pads on the PCB that are wired directly to the UFS interface. This technique is essential when standard software-based flashing tools cannot reach the device, such as when a bootloader is corrupted, the device is hard-bricked, or software FRP removal has failed. For the Samsung SM-A256, ISP access targets the UFS interface lines exposed on the motherboard, enabling read, write, and erase operations at the raw storage level.

SM-A256 ISP Pinout Diagram

The Samsung SM-A256 (Galaxy A25 5G) uses a UFS 2.2 storage interface. The ISP test points are located on the rear face of the main PCB, typically near the UFS chip. The key pads are as follows:

  • VCC — 2.9 V power supply to UFS (main supply rail)
  • VCCQ — 1.8 V I/O voltage for UFS interface signals
  • GND — Ground reference
  • RST — UFS reset line (active low)
  • DATA0+ / DATA0− — UFS differential data lane 0 (TX/RX pair)
  • DATA1+ / DATA1− — UFS differential data lane 1 (TX/RX pair)
  • REF CLK — Reference clock input to UFS device

Note: Exact pad coordinates and silkscreen labels for the SM-A256 PCB revision are not yet confirmed in public schematics. Refer to your ISP adapter manufacturer's latest pinout card for verified pad mapping before probing.

When Technicians Use ISP

ISP access on the SM-A256 is most commonly required in the following scenarios: the device is completely dead and does not respond to any USB connection; the bootloader partition has been corrupted during a failed OTA or manual flash; FRP (Factory Reset Protection) lock cannot be cleared through ADB, download mode, or standard unlocking tools; or the device is stuck in an endless boot loop caused by a damaged system partition. Because the SM-A256 runs Android 14 with Samsung's latest security patches, software-level FRP methods are frequently ineffective, making hardware ISP the reliable fallback.

How To Access ISP Points

Follow these steps to safely establish an ISP connection on the SM-A256:

  • Fully discharge the battery or disconnect it before opening the device.
  • Disassemble the rear panel and carefully remove the motherboard using appropriate spudgers and heat.
  • Identify the UFS ISP test pads on the rear of the PCB using a verified schematic or ISP adapter template.
  • Clean the pads with IPA and a soft brush to ensure good contact.
  • Attach an ISP adapter (e.g., EasyJTAG UFS adapter or UFI Box adapter) by aligning the pogo pins precisely to the pads.
  • Connect the adapter to your PC and launch your ISP tool (EasyJTAG Plus, UFI Box, or UMT).
  • Apply power only through the tool — do not reconnect the battery during ISP operation.
  • Perform the desired operation: read, write, or FRP erase, and safely disconnect before reassembly.

Safety Tips and Precautions

Working with UFS ISP carries real risk of permanent data loss or component damage if done incorrectly. Always observe these precautions:

  • Never exceed 1.8 V on VCCQ lines; over-voltage will destroy the UFS interface controller instantly.
  • Use ESD protection — wear an anti-static wrist strap and work on a grounded mat.
  • Double-check polarity and pad alignment before applying power; reversed connections can short the power rails.
  • Do not interrupt power during a write or erase operation — this will brick the UFS permanently.
  • Always back up a full dump before performing any erase or write operation.
  • Use only tools with SM-A256 / Exynos 1280 verified support to avoid incompatible voltage profiles.

Pin / Test Point Reference

PinDescription
VCCMain power supply to UFS chip (2.9 V) — Do not exceed rated voltage
VCCQI/O voltage rail for UFS signals (1.8 V) — Critical — overvoltage destroys UFS
GNDGround reference pad
RSTUFS reset signal (active low)
DATA0+UFS differential data lane 0 positive (TX/RX) — Handle as matched impedance pair
DATA0−UFS differential data lane 0 negative (TX/RX) — Handle as matched impedance pair
DATA1+UFS differential data lane 1 positive (TX/RX)
DATA1−UFS differential data lane 1 negative (TX/RX)
REF CLKReference clock input to UFS device

Tools required: EasyJTAG Plus with UFS adapter, UFI Box, UMT (Ultimate Multi Tool), Medusa Pro II, ISP pogo-pin adapter for SM-A256

Supported operations: Read Firmware / Full Dump, Write Firmware, FRP Erase, Dead Boot Repair, IMEI Repair (where legally permitted), Partition Erase

⚠ Safety note: Use 1.8 V VCCQ only — overvoltage permanently destroys the UFS IC. Always disconnect the battery before probing. Never interrupt power during write/erase.