J-Mem memory viewer is a GUI application to display and modify the RAM and SFRs (Special Function Registers) of target systems while the target is running. J-Mem is part of the J-Link Software and Documentation Pack, which is available for download on the SEGGER webpage.
Setting up J-Mem
When starting J-Mem a configuration dialog pops up, letting you select the needed configurations to connect to J-Link and the target.
Note: To make sure the connection to the target device can be established correctly, the device, as well as the interface and interface speed have to be given on start of J-Mem.
J-Mem user interface
The user interface of J-Mem shows the content of a memory region from the target that J-Link is connected to. Furthermore, details about the connection to the target are displayed in the status bar.
The memory window provides a range of different options regarding the displayed memory.
In the following, these options are explained in detail from left to right (as seen in the screenshot above).
- 1 refers to 8-bit access,
- 2 refers to 16-bit access and
- 4 refers to 32-bit access.
A custom <Fill Value> can be chosen that the selected memory region is filled with. The region to fill can be determined by setting the <Start Address> and either the <End Address> or <Size>.
Save memory data
Similar to the "Fill memory" option, the memory region to be saved can be determined by setting the <Start Address> and either the <End Address> or <Size>.
By default, J-Mem only reads the memory to be displayed once when it is shown for the first time. Using the "Periodic Refresh" option, a time interval for the refresh rate of the displayed data can be set.
One of the following intervals can be selected:
- 100 ms
- 200 ms
- 500 ms
- 1 s
- 2 s
- 5 s
The time interval "off" is the default and does not refresh the displayed memory periodically.
Command line options
There are no command line options available for J-Mem.