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Capture DDR Contents With JTAG Interface

Last modified by Microchip on 2026/08/17 10:41

For Load Pre-saved Snapshot Image mode, you must manually capture the raw DRAM context through the JTAG interface.

The standard boot sequence starting from ROM boot begins. 

The kernel and application are ready.

Enter Snapshot mode by typing the following command:

> echo mem > /sys/power/state

Connect JTAG interface and run the SEGGER® J-Link® executable file on the host computer.

> connect
> speed 20000

J-Link.exe file

Save Double Data Rate (DDR) content.

Halt the CPU.

> Halt

Disable Memory Management Unit (MMU).

For SAM9X60 or SAM9X7 series:

> wce 0 1 0 0 0x0005217A

For SAM5 or SAMA7 series:

> wce 0 1 0 0  0x10C53C7c

Save to a binary file.

savebin <filename>, <addr>, <NumBytes> (hex)

For example:

Save SAM9X60 DDR context from 0x20000000, size 0x8000000 (128 MB).

> savebin binary.bin 0x20000000 0x8000000

Save SAM7D65 DDR context from 0x60000000, size 0x20000000 (512 MB).

> savebin binary.bin 0x60000000 0x20000000
Warning

Saving 128 MB of data from DRAM takes approximately 15 minutes, while saving 256 MB of data takes 30 minutes by JTAG interface.

Jlink.exe file

Power off the board.

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