SystemView

Yes. SystemView can run in parallel with a debugger and perform continuous recording. To ensure that data can be read fast enough, configure the debugger connection to use a high interface speed (≥ 4 MHz). Parallel connections to a target are currently supported only on Windows and Linux.

Yes. SystemView can generally be used with any J-Link that supports the target core. Older J-Links (V8 and earlier) may have limited RTT capabilities, which can result in overflow events if the RTT buffer cannot be read fast enough while many events are generated. Information about trade-in or upgrade options can be found in the purchase section.

This depends on the target device. RTT requires memory access while the target is running. On Cortex-A and Cortex-R devices, this is performed via the AHB-AP. If the device provides an AHB-AP, continuous recording with SystemView is possible.

No. RTT requires memory access while the target is running. On ARM7 and ARM9 devices, only single-shot and post-mortem recording modes are supported.

Yes. SystemView can be used with any RTOS. For task and OS execution recording, the operating system must provide hooks or trace instrumentation that SystemView can integrate with. Otherwise, the OS must be instrumented manually. If this is not possible, SystemView can still be used to record interrupt activity and user-defined events.

Yes. Even without an operating system, SystemView can record interrupt activity, verify that interrupts occur as expected, and record user events that can be used to measure module execution times.

Overflow events occur when the SystemView RTT buffer becomes full. This can happen for several reasons:

• J-Link is busy due to debugger activity and cannot read data fast enough.
• The target interface speed is too low.
• The application generates more events than fit into the buffer.

To reduce the likelihood of overflow events:

• Minimize debugger interaction while the target is running, for example by disabling live watches.
• Select a higher interface speed for all tools connected to J-Link, including the debugger and SystemView.
• Increase the size of the SystemView buffer (1 to 4 kByte).
• Run SystemView in stand-alone mode without a debugger.

Ensure that approximately 200 bytes of stack space are available for SystemView in every context that can generate SystemView events, including tasks, interrupts, and the scheduler.

Possible reasons include:

• J-Link or the target is not connected. Verify that all connections are correct.
• The target is not running. If the target is stopped, the RTT Control Block may not be found.
• The SystemView module is not configured. Ensure that the SystemView module is included in the application and that SEGGER_SYSVIEW_Conf() is called during startup.
• The J-Link Software is outdated. Make sure the latest J-Link Software and Documentation Package is installed.

Automatic detection of the RTT Control Block is only possible within a known RAM address range after initialization. Ensure that application startup has completed before starting a recording. If the RTT Control Block is located outside the known range for the selected device, select Address and enter the exact address, or select Address Range and specify a range that contains the RTT Control Block.

Invalid packets are typically generated by the target system for one of the following reasons:

• SystemView does not correctly lock while recording an event and is interrupted by another event. In this case, verify that SEGGER_SYSVIEW_LOCK() and SEGGER_RTT_LOCK() are configured correctly for the device.
• The system enters sleep or low-power mode, preventing J-Link from reliably accessing RAM. It is recommended not to use WFI or other low-power modes while a debug probe is connected.

Yes. J-Link must know which target device is connected. The drop-down list shows the most recently used devices. To select another device, simply enter its name. A list of supported devices is available in the device selection dialog.