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Recipe · Beginner · SPI flash

How to dump a SPI flash chip from your browser

I had a small router board with an 8-pin flash and no firmware download. Before erase, write, or experiments, the job was simple: make a clean backup and keep it untouched.

SPI flash memory chip on an SPI bus.
For flash repair work, the first useful artifact is a known-good dump, not a clever patch.

Wiring View

SPI flash BP Flash CS GPIOchip CS#Flash SCK GPIOchip CLKFlash MISO GPIOchip DO / IO1Flash MOSI GPIOchip DI / IO0BP GNDchip GND3.3Vchip VCC
Generated from the wiring summary: SPI flash to BP.
Step 1

Put Bit Pirate in flash adapter mode

The browser flash tool talks to the dedicated Flashrom serprog adapter. Start it from USB adapter mode, choose the flash adapter, enter your selected GPIOs, then let the board reboot into that USB mode.

Step 2

Use the browser tool

  1. Open the Web SPI Flash Programmer.
  2. Click Connect and select the Bit Pirate serial port exposed by the adapter.
  3. Click Probe chip. Check JEDEC ID, likely chip, and capacity.
  4. If the chip ID is stable, use Dump chip.
  5. Use Save full dump and keep the original file read-only in your project folder.

What the result means

Good sign

A stable JEDEC ID and the same capacity after repeated probes usually means the clip, power, and SPI lines are usable. For anything important, dump twice and compare the files before trusting the backup.

Troubleshooting

A changing JEDEC ID is usually physical: clip alignment, long wires, weak power, wrong chip voltage, or the target board pulling on the bus. Slow down the setup before increasing speed or trying a write. A bad backup is worse than no backup because it feels reassuring.

  • WP# or HOLD# are floating when the chip expects them high.
  • The board is still powered and another chip is driving the SPI bus.
  • The SOIC clip is shifted by one pin or barely touching.
  • Only one dump was saved, so there is nothing to compare.

SPI flash browser dump FAQ

Why keep hashes for flash dumps?

Hashes let you compare backup files without reopening them byte by byte. Matching hashes are a compact way to document that two reads produced the same image.

Can I dump a SPI flash chip in-circuit?

Sometimes, but in-circuit access can fail if the target board powers the chip, holds reset lines, or drives the same SPI bus. A socket or removed chip is more reliable for important backups.

Why is detected capacity important before dumping?

The detected capacity defines how much data a full-chip dump should read. It also gives you a sanity check before comparing backups or deciding whether a file matches the chip.

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