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 without relying on the main CPU or operating system. By locating and connecting to specific test pads on the PCB, a programmer tool can read, write, or erase the storage at the raw data level. This technique is essential when standard software flashing tools such as Odin or QFIL fail to detect the device, making ISP the last reliable option for low-level data recovery and repair.

On the Samsung Galaxy A72 (SM-A725), ISP access bypasses the Snapdragon 720G SoC and interfaces with the UFS storage directly through dedicated test points arranged on the motherboard. This enables operations that are otherwise impossible through USB-based flashing methods.

SM-A725 ISP Test Points

The Samsung Galaxy A72 uses a UFS 2.1 storage interface rather than a standard eMMC bus. The ISP pads on the SM-A725 motherboard are small exposed copper contacts typically located near the UFS storage chip on the rear side of the main PCB. The primary signal lines required for UFS ISP access are:

  • VCCQ — 1.2 V I/O supply for the UFS PHY layer
  • VCC — 2.95 V main power supply to the UFS chip
  • GND — Common ground reference
  • RESET — Active-low reset line to the UFS device
  • DATA+ / DATA− — Differential MIPI M-PHY lanes (TX and RX pairs)
  • REF CLK — Reference clock line for the UFS PHY

Exact pad coordinates on the SM-A725 PCB have not been independently verified in a publicly confirmed schematic; technicians should cross-reference a known-good board pinout diagram or use a continuity meter to confirm pad identity before connecting any programmer.

When Technicians Use ISP

ISP access on the Galaxy A72 is typically required in three main scenarios. First, dead-boot repair: if the device fails to power on after a failed OTA update or interrupted Odin flash, ISP allows the firmware to be rewritten directly. Second, pattern or FRP lock removal: when the device is hard-locked and no EDL or download mode is accessible, ISP can erase the relevant partition. Third, flash corruption recovery: bad blocks, corrupted bootloaders, or wiped partition tables can be rebuilt by writing a full firmware dump via the programmer.

Accessing the Test Points

Follow these steps to perform ISP access on the SM-A725:

  • Fully discharge the battery and disconnect it from the motherboard before any work.
  • Remove the motherboard from the chassis and clean the PCB surface around the UFS area with isopropyl alcohol (99%).
  • Identify the UFS ISP pads using a verified schematic or pinout diagram.
  • Solder thin gauge (0.1 mm) enamelled wire to each pad — CLK, CMD/DATA lanes, VCC, VCCQ, GND, and RESET.
  • Connect wires to the appropriate ISP socket or direct wire port on your programmer.
  • Open your programmer software, select Samsung SM-A725 or the matching UFS profile, and power the board through the programmer's regulated supply.
  • Execute read, erase, or write operations as required.

Safety Tips and Precautions

Working at the ISP level carries significant risk. Always observe the following precautions:

  • Never apply more than 2.95 V to VCC or 1.2 V to VCCQ — over-voltage will permanently damage the UFS chip.
  • Confirm GND continuity before powering the board to avoid short circuits.
  • Always create a full NAND dump before erasing or writing any partition.
  • Use a current-limited bench supply set to 300 mA maximum during initial connection testing.
  • Avoid touching exposed pads with bare hands — static discharge can corrupt or destroy the UFS storage.
  • Work in a well-lit environment with a stereo microscope to prevent solder bridges between adjacent pads.

Pin / Test Point Reference

PinDescription
VCCMain power supply to UFS chip — 2.95 V — Supplied via programmer regulated output
VCCQI/O power supply for UFS PHY — 1.2 V — Separate rail from VCC; do not tie together
GNDCommon ground reference for all ISP signals — Verify continuity before powering board
RESETActive-low hardware reset line to UFS device
DATA+ / DATA−MIPI M-PHY differential TX/RX lane pair for UFS data transfer — Keep wire length equal and as short as possible
REF CLKReference clock input to UFS PHY — typically 19.2 MHz — Frequency may vary; confirm with programmer profile

Tools required: EasyJTAG Plus with UFS adapter, UMT (Ultimate Multi Tool) with ISP cable, Medusa Pro II with UFS box, Soldering station (fine tip, ≤300 °C), 0.1 mm enamelled copper wire, Stereo microscope, Current-limited bench power supply, 99% isopropyl alcohol and brush

Supported operations: Read Full NAND Dump, Write Firmware, FRP Erase, Dead Boot Repair, Partition Table Restore, User Data Wipe, IMEI Backup (read only)

⚠ Safety note: UFS VCC must not exceed 2.95 V; VCCQ must not exceed 1.2 V. Over-voltage permanently destroys the storage chip. Always dump NAND before any write or erase operation.