J-Link Control Panel

The J-Link web control panel allows the user to monitor the J-Link status and the target status information in real-time. It also allows the user to configure the use of some J-Link features such as flash download, flash breakpoints and instruction set simulation. The J-Link web control panel can be accessed via the J-Link tray icon () in the tray icon list or via http://localhost:19080. This icon is available when a debug session is started. To open the status page, simply click on the tray icon.

Tabs

The J-Link web control panel supports different features which are grouped in tabs. The organization of each tab and the functionality which is behind these groups will be explained in this section.

General

Web control panel - General tab

In the General section, general information about J-Link and the target hardware is shown:

Element	Meaning
Process	Path of the file which loaded the DLL.
Module	Path of the DLL invoking this Web control panel instance.
Version	DLL version and compile date.
J-Link	OEM of the connected J-Link, the hardware version and the Serial number.
Selected device	Selected device.
Endian	Target endieness.
Voltage	Target current measured between ground pin (GND) and reference pin (VTref).
Target interface	Shows the selected target interface (JTAG/SWD) and the current JTAG speed.
Host interface	Shows the host interface that is selected and the IP or SN of the J-Link.

Settings

Web control panel - Settings tab

In the Settings section project- and debug-specific settings can be set. It allows the configuration of the use of flash download and flash breakpoints and some other target specific settings which will be explained in this topic. Settings are saved in registry.

Files

In the Files section, the following information is shown:

Element	Meaning
Log file	Path to the active J-Link log file.
Settings file	Path to the active Settings file.
Script file	Path to the currently used J-Link script file.

Additionally, the log file override can be activated. If activated, the J-Link log file will be created at the path shown under "Log file".

Flash download

In the Flash download section, settings for the use of the J-Link FlashDL feature and related settings can be configured.

Element	Explanation
Flash download	On - Enables the J-Link FlashDL feature. Off - Disables the J-Link FlashDL feature.
Compare	Compare method.
L1-Verify	Disable/Enable L1 verify.
L2-Verify	L2 verification method.
Status	Enabled (green LED) - Flash downloads enabled. Disabled (red LED) - Flash downloads disabled

Flash breakpoints

In the Flash breakpoint section, settings for the use of the FlashBP feature and related settings can be configured. When a license for FlashBP is found, the color indicator is green and "Enabled, license found" appears right to the FlashBP usage settings.

Element	Explanation
Flash breakpoints	Selection Meaning Auto This is the default setting of FlashBP usage. If a license has been found the FlashBP feature will be enabled.Otherwise FlashBP will be disabled internally. On Enables the FlashBP feature. Off Disables the FlashBP feature.
Show window during program	When this checkbox is enabled the "Programming flash" window is shown when flash is re-programmed in order to set/clear flash breakpoints.
Status	Indicates if flash breakpoints are enabled and if a license for the FlasBP feature was found.

Misc

In the Misc. section, some additional settings can be set.

Element	Explanation
Override device selection	If enabled, Manual device selection is enabled. This especially makes sense when J-Link can not identify the device name given by the debugger or if a particular device is not yet known to the debugger, but to the J-Link software.
Allow caching of flash contents	If enabled, the flash contents are cached by J-Link to avoid reading data twice. This speeds up the transfer between debugger and target.
Allow instruction set simulation	If enabled, instructions will be simulated as far as possible. This speeds up single stepping, especially when FlashBPs are used.
Modify breakpoints during execution	Allows the user to change the behavior of the DLL when setting breakpoints if the CPU is running. The following options are available: Selection Meaning Allow Allows settings breakpoints while the CPU is running. If the CPU needs to be halted in order to set the breakpoint, the DLL halts the CPU, sets the breakpoints and restarts the CPU. Allow if CPU does not need to be halted Allows setting breakpoints while the CPU is running, if it does not need to be halted in order to set the breakpoint. If the CPU has to be halted the breakpoint is not set. Ask user if CPU needs to be halted If the user tries to set a breakpoint while the CPU is running and the CPU needs to be halted in order to set the breakpoint, the user is asked if the breakpoint should be set. If the breakpoint can be set without halting the CPU, the breakpoint is set without explicit confirmation by the user. Do not allow It is not allowed to set breakpoints while the CPU is running.

Breakpoints

Web control panel - Breakpoints tab

In this section all breakpoints and watchpoints which are in the DLL internal breakpoint and watchpoint list are shown.

Note:

It is possible for the debugger to bypass the breakpoint functionality of the J-Link software by writing to the debug registers directly. This means for ARM7/ARM9 cores write accesses to the ICE registers, for Cortex-M3 devices write accesses to the memory mapped flash breakpoint registers and in general simple write accesses for software breakpoints (if the program is located in RAM). In these cases, the J-Link software cannot determine the breakpoints set and the list is empty.

Set code breakpoint

In this section, a code breakpoint can be set.

Element	Explanation
Adress	Specifies the Address of the breakpoint to be set.
Mode	Defines if the break point to be set is in Thumb or ARM bode.
Permitted	Defines which kind of breakpoints is permitted: SoftBP (RAM) SoftBP (Flash) Hardware
Set	Sets a break point with the specifications defined above.

Set watchpoint

In this section, a code breakpoint can be set.

Element	Explanation
Adress	Specifies the address of the watchpoint to be set.
Adress mask	Specifies the address mask used for comparison. Bits set to 1 are masked out, so not taken into consideration during address comparison.
Access type	Defines which type of access is watched. Selection Meaning Read Trigger on read access only Write Trigger on write access only Any Trigger on any access type
Access size	Specifies the access size on which the watchpoint will trigger. Selection Meaning S8 Trigger on 8-bit accesses only S16 Trigger on 16-bit accesses only S32 Trigger on 32-bit accesses only Any Trigger on all accesses.
Data	Specifies the Data on which the watchpoint is to be set.
Data Mask	Specifies data mask used for comparison. Bits set to 1 are masked out, so not taken into consideration during data comparison.
Set	Sets a break point with the specifications defined above.

Example - Set watchpoint

• Do break on access to address 0x20000000
• Do break only on access to this specific address, and not on an address range
• Do break on any access type
• Do break on all access sizes
• Do not care for the value of the data at this address.

Address:	0x20000000
Address mask:	0x0
Data:	0x0
Data mask:	0xFFFFFFFF

Code breakpoints

List of all code breakpoints which are in the DLL internal breakpoint list.

Element	Explanation
Handle	Handle of the breakpoint.
Address	Address where the breakpoint is set.
Permitted impl.	Permitted implementation (see "Permitted" in Set code breakpoint).
Actual impl.	The actual breakpoint implementation type.

Data breakpoints

List of all data breakpoints which are in the DLL internal breakpoint list.

Element	Explanation
Handle	Handle of the breakpoint.
Address	Address where the breakpoint is set.
Data	Breakpoint data and mask.
Access	Access type (8-, 16-, 32-bit, Write/Read).
Unit	Unit type.

Vector catch

List of all active vector catches which are in the DLL internal list.

Element	Explanation
Vector	Vector, a catch is enabled for.

RTT

Web control panel - RTT tab

The RTT tab is a RTT interface. It provides

• general information about the current RTT session.
• the ability to start and stop RTT.
• RTT I/O functionality (reading and sending RTT data via different channels).

For general information about RTT, please refer to RTT.

Manual start

Element	Explanation
Control block address	Address of the RTT control block (Set by user).
Start button	Starts RTT.

Status & Settings

This sections shows information about the current RTT session and provides the selection of some RTT settings.

Element	Explanation
Running	LED indicating if RTT is active or not (green == active)
TELNET port	TELNET port used for RTT.
Status	Status of the RTT session. Indicates, if the RTT control block has been found and the address it was found at.
Mode	RTT mode used.
Control block	Shows the control block address and how it was found.
Data rate	Data rate [bytes/s].
Total received	Total data received via RTT [bytes].
Buffered	Data currently buffered in the DLL [bytes].

Target -> Host

This section handles the data from target to host.

Element	Explanation
Show data for channel	Selects from which channel data is supposed to be shown.
Clear button	Clears the received data log.
Log	Shows the data received from the target via RTT.

Host -> Target

This section handles the data from host to target.

Element	Explanation
Show data for channel	Select the channel data is supposed to shown for.
Show data as	Select if data is shown as bytes (HEX) or strings.
Send CR on <Return>	If checked a carriage return (\r) character is appended to the data sent to the target.
Send LF on <Return>	If checked a line feed (\n) character is appended to the data sent to the target.
Clear button	Clears the sent data log.
Log	Shows the data received from the target via RTT.
Line edit	Data to be sent to the target.
Send button	Sends the data inside the line edit to the target device.

Log

Web control panel - Log tab

In this section the log output of the DLL is shown. Additionally, some filters can be applied and the active DLL time + the count of API calls is shown. The user has the following options:

• Filtering the log
• Clear the log
• Start and Stop showing data in the Log window.

CPU Regs

Web control panel - CPU Regs tab

The CPU regs tab shows the name and the value of the CPU registers. Additionally, the user can set the values currently written in the CPU registers.

Target Power

Web control panel - Target Power tab

The target power Tab provides information about the following:

• Current on USB side
• Current on Target side.
• Power consumption on target side (see Target Power - Limitations)
• Current state of the reset pin
• Count of detected reset pulses

The user can also change the power configuration of the J-Link in this tab.

Target Power - Limitations

The power consumption feature, as well as the power configuration feature can only be used if the connected probe supports it. The J-Link EDU Mini for example does not support these features.

SWV

Web control panel - SWV tab

In the SWV tab, SWV information is shown.

Element	Explanation
Status
Capabilities	Available SWV baudrates supported by the connected emulator.
Status	Encoding and baudrate of the SWV data received by the target (Manchester/UART, currently J-Link only supports UART encoding).
Bytes transferred	Total bytes transferred via SWV since debug session start.
Refresh counter	Total count of SWV information updates in this section since debug session start.
Refresh interval	Refresh interval.
Host buffer
Size	Reserved buffer size for SWV data on host side.
Used	Used bytes of the host buffer.
Emulator buffer
Size	eserved buffer size for SWV data on emulator side.
Used	Used bytes of the emulator buffer.
Analyzed SWO data
Log window	SWO data package information.

RAWTrace

Web control panel - RAWTrace tab

Status

Element	Meaning
Status	Trace status. If active, shows the Trace clock in [Hz].
Start Count	Trace start count. Shows how often trace was started during the current debug session.
NumBytes	NumBytes read from the Trace buffer / NumBytes of data in the Trace buffer.
Trace Buffer Size	J-Link internal trace buffer size.
Supported modes	Supported ETN-Trace modes (1-,2-,4-bit tracing).

Trace data

Element	Meaning
Raw data	Raw trace data received from device.
Frame data	Raw trace data as frames (without Full-Syncs).
Payload data	Data read from frames for ETM-ID.
ETM analyzed	Gapless program flow analysis results.

LiveTrace

Web control panel - LiveTrace tab

Element	Meaning
Packets
Received	Number of packets received and connection details (USB/IP + Address).
Lost (current)	Number of packets lost since Trace start
Lost (total)	Number of total packets lost during the debug session.
Lost List	Packet lost list counter.
Analyze info
Analyze info	Shows information about analysis speeds and analyzed packets.
Trace buffer
In use	Shows current and maximum number of the Trace buffers that are in use / can be used.
Raw data
Buffers	Number of raw trace buffers currently active Max number of buffers available Size per buffer
In Use	Number of raw trace buffers currently in use Peak of buffers in use
Total	Size of raw trace data written into buffer since start of trace.
Speed	Current raw trace data rate Peak raw trace data rate
ETM data
Buffers	Number of ETM trace buffers currently active Max number of buffers available Size per buffer
In Use	Number of ETM trace buffers currently in use Peak of buffers in use
Total	Size of ETM trace data written into buffer since start of trace.
Speed	Current ETM trace data rate Peak ETM trace data rate

Flash

Web control panel - Flash tab

The Flash tab shows the addresses and internal names of the flash banks supported for the connected device. Furthermore the areas of cached memory are shown.

Commander

Web control panel - Web Commander

The J-Link Web Commander provides a terminal that can be seen as a smaller version of the J-Link Commander, with a significantly smaller command set. This way, the user can adjust settings and read/write memory, from an active debug session. This is especially useful when using IDEs that only provide limited features which the J-Link provides by default.

Command	Explanation	Syntax
?	Show available commands.	?
exec	Execute J-Link command string.	exec <Command>
mem8	Read 8-bit memory (hex).	mem8 <Addr[hex]>,<NumItems[hex]>
mem16	Read 16-bit memory (hex).	mem16 <Addr[hex]>,<NumItems[hex]>
mem32	Read 32-bit memory (hex).	mem32 <Addr[hex]>,<NumItems[hex]>
w1	Write 8-bit to target (hex).	w1 <Addr[hex]>,<Data>
w2	Write 16-bit to target (hex).	w2 <Addr[hex]>,<Data>
w4	Write 32-bit to target (hex).	w4 <Addr[hex]>,<Data>
ih	Checks if the target is halted.	ih
clear	Clear terminal.	clear

Help

Web control panel - Help tab

The Help tab provides links to useful information sources.