What Is ISP Pinout

ISP (In-System Programming) is a hardware-level recovery method that allows technicians to communicate directly with a device's eMMC or UFS storage chip without relying on the main processor or bootloader. By connecting a compatible programmer to dedicated test pads on the PCB, the storage can be read, written, or repaired even when the device is completely unresponsive — a situation where software-based tools fail entirely.

For the Samsung Galaxy A9 2018 (SM-A920), ISP access is particularly valuable because the Snapdragon 660 platform can enter hard-brick states that block normal EDL (Emergency Download Mode) entry. ISP bypasses those software dependencies entirely, enabling direct manipulation of the UFS storage at the hardware layer. This makes it the method of choice for advanced repair scenarios including user data extraction, firmware restoration, and security partition erasure.

SM-A920 ISP Pinout Map

The SM-A920 uses a UFS 2.1 storage interface rather than a traditional parallel eMMC bus. The ISP test points correspond to the UFS differential lanes and power rails exposed on the board. The primary pads are located near the UFS storage IC on the main PCB, typically accessible after removing the motherboard from the chassis. Always verify pad locations under magnification before connecting.

  • CLK+ / CLK− — Differential reference clock lines for UFS timing synchronization
  • DATA+ / DATA− — Primary UFS data lane (RX/TX differential pair)
  • VCC — Main storage supply voltage (typically 2.9 V)
  • VCCQ — I/O supply voltage for UFS interface (typically 1.8 V)
  • GND — Common ground reference
  • RST — Reset line for storage controller initialization

Exact pad coordinates on the PCB silk layer are not universally published for this model. Use a high-resolution board schematic or verified ISP photo reference before probing.

When Technicians Use ISP

ISP is selected over other recovery methods in the following situations:

  • Device is hard-bricked and will not enter EDL or Download Mode through software or button combinations
  • FRP (Factory Reset Protection) must be erased when the device is fully non-functional
  • The bootloader is corrupt and standard Odin flashing is impossible
  • User data recovery is required from a device with a damaged display or power circuit
  • Userdata or EFS partition needs to be directly backed up or restored

Accessing the Test Points

Follow this procedure carefully to connect a programmer to the SM-A920 board:

  1. Power off the device completely and disconnect the battery connector on the motherboard.
  2. Remove the motherboard from the chassis and clean the area around the UFS IC with IPA.
  3. Identify the ISP test pads using a verified schematic or trusted photo reference under a microscope.
  4. Solder fine gauge wire (30–32 AWG) to each pad: CLK+, CLK−, DATA+, DATA−, VCC, VCCQ, GND, and RST.
  5. Connect wires to the appropriate ISP adapter or socket on your programmer (e.g., EasyJTAG Plus UFS adapter).
  6. Launch your programmer software, select the SM-A920 or SDM660 UFS profile, and power the board through the programmer — do not reconnect the battery.
  7. Perform the desired operation: read, write, or erase specific partitions.

Safety Tips and Warnings

ISP work on UFS devices carries significant risk if performed incorrectly. Observe the following precautions at all times:

  • Voltage: UFS VCCQ is 1.8 V. Applying incorrect voltage will permanently destroy the storage IC. Verify programmer output voltage before connecting.
  • ESD: Always work on an anti-static mat and wear a grounded wrist strap. UFS controllers are highly susceptible to electrostatic discharge.
  • Data loss: Any write or erase operation is irreversible. Back up partitions before modifying them whenever possible.
  • Pad damage: Test pads are small and fragile. Excessive heat or mechanical force will lift pads, making recovery impossible.
  • Software profile: Always select the exact device profile in your programmer. A mismatch can corrupt the partition table.

Pin / Test Point Reference

PinDescription
CLK+UFS differential clock positive lane — Part of high-speed differential pair; handle with matched-length wiring
CLK−UFS differential clock negative lane — Must be paired with CLK+ for correct timing
DATA+UFS primary data lane positive (RX/TX) — Main storage data path
DATA−UFS primary data lane negative (RX/TX) — Must be paired with DATA+
VCCUFS main power supply, typically 2.9 V — Confirm voltage with programmer spec before connecting
VCCQUFS I/O voltage, typically 1.8 V — Critical — overvoltage will destroy UFS IC
GNDCommon ground reference pad — Multiple ground pads available near UFS IC
RSTUFS storage reset line — Required for proper initialization sequence

Tools required: EasyJTAG Plus with UFS adapter, UFI Box with UFS socket/ISP cable, Riff Box 2, 30–32 AWG magnet wire, Hot air rework station, Digital microscope or stereo microscope, Anti-static mat and wrist strap, Isopropyl alcohol (99%) and brush

Supported operations: Read Full Firmware (UFS dump), Write Firmware / Restore Dead Boot, FRP Erase, EFS Backup and Restore, Userdata Partition Wipe, Bootloader Repair, IMEI Repair (via EFS write)

⚠ Safety note: UFS VCCQ is 1.8 V — incorrect voltage permanently destroys storage. Use ESD protection at all times. All write/erase operations are irreversible. Verify pad locations with a schematic before soldering.