Ozone Online Breakpoint Debugging Guide

This section describes how to use Ozone for breakpoint and step-by-step debugging.

1. Early Crash Breakpoint Setup

If the system crashes during the Bootloader phase, immediately after Bootloader, during early startup initialization (or during sleep wake-up), attaching J-Link directly is often too late. You can set breakpoints directly in the code.

• Assembly level setup: Add a B . infinite loop in the Reset_Handler of drivers/cmsis/sf32lb5xx/Templates/arm/startup_bf0_hcpu.S (replace with the corresponding chip model).

Note: The path for startup_bf0_hcpu.S when compiling with GCC differs from Keil. The GCC path is: drivers/cmsis/sf32lb5xx/Templates/gcc/startup_bf0_hcpu.S

Reset_Handler   PROC
                B        . ; // First instruction executed after MCU reset, add breakpoint

• C language level setup: Add an assembly-level breakpoint at the beginning of SystemInit() or rtthread_startup().

__asm("B ."); // Set breakpoint

Or:

HAL_sw_breakpoint(); // Set breakpoint

Note

Do not use while(1); as a breakpoint, because compiler optimizations may discard all statements after it.

After setting this, the system will halt at that instruction. After connecting J-Link and Ozone, use the command setpc PC+2 to advance the PC register by 2 bytes to skip the breakpoint, then you can start step-by-step tracing.

2. Ozone Debugging Guide

Ozone is SEGGER’s official full-featured debugger, which is more stable than Keil for crash investigation and multi-core debugging.

J-Link connects to HCPU by default. If debugging HCPU, this step can be skipped. If you need to debug LCPU, execute the corresponding batch script in a Windows CMD window, such as SIFLI-SDK\tools\segger\jlink_lcpu_a0.bat (55 series), jlink_lcpu_pro.bat (58 series), or jlink_lcpu_56x.bat (56 series). This batch file executes a few low-level commands. You can also enter these two commands directly in the J-Link window to manually switch to LCPU:

w4 0x4004f000 1
connect
w4 0x40070000 0
exit

(Note: You can also switch SWD to LCPU debugging by writing registers directly in code.)

2.1 Creating an Ozone Project and Connecting

Create a new project: Open Ozone and create a new project.

Select the debug chip: Navigate to the SIFLI-SDK\tools\svd_external path and select the corresponding chip model directory to open and select the SVD file.

Select connection interface: Select J-Link (SWD/JTAG). If not found, check the connection and power supply.

Select firmware: Select the compiled *.axf or *.elf file. Note the file extension difference: Keil-compiled files have the .axf extension, while GCC-compiled files have the .elf extension.

In Ozone, select File then Open, and find the firmware you want to import.

Attach to program:

• Attach & Halt Program: Connect J-Link to the CPU and halt at the current PC pointer (recommended for crash investigation).

• Attach & Run Program: Connect to the CPU and continue running from the current PC.

Start debugging: After clicking the run program arrow icon, the CPU can be stepped through. You can add breakpoints, view call stack information, and register states.

2.2 Common Ozone Debugging Issues

Issue 1: Target Connection Lost - Frequent Disconnections After Connecting

The following disconnection dialog frequently appears shortly after connecting, interrupting the debugging session:

Cause and Solution: This occurs because when connecting to Ozone for debugging, the Memory window is enabled by default and reads uninitialized (such as PSRAM) or non-existent memory addresses, causing read failures and disconnections. Before connecting for debugging, make sure to close Ozone’s Memory window and other unused windows.

Issue 2: Enabling RT-Thread RTOS Thread Awareness in Ozone

To view system threads in Ozone, copy the plugin \tools\segger\RtThreadOSPlugin.js from the SDK to the Plugins\OS\ directory under the Ozone installation path. Reopen the project and enable Project.SetOSPlugin("RtThreadOSPlugin"); to switch and debug RT-Thread threads online.

Issue 3: Ozone Shows “File not found” (Redefining Source Code Path)

When the flashed binary was not compiled locally (e.g., investigating a crash scene sent by someone else), Ozone shows File not found and cannot locate the C source code for step-by-step tracing.

Solution:

• Single file not found: Right-click the file, select Locate File, and navigate to the corresponding local C source file.

• Batch file base address mismatch: Enter the Project.AddPathSubstitute command in the Ozone command window to relocate the path. For example, replace the Linux compilation path in the ELF with the local Windows path.

Issue 4: Ozone Debug Connection Fails

Error shown:

Solution: You need to add the flash driver and XML configuration file just like for J-Link, so that Ozone is supported.

C:\Program Files\SEGGER\Ozone\Devices\SiFli\SF32LB55X****.elf
C:\Program Files\SEGGER\Ozone\JLinkDevices.xml
# Different J-Link or Ozone versions may have the following paths:
C:\Users\yourname\AppData\Roaming\SEGGER\JLinkDevices.xml
C:\Users\yourname\AppData\Roaming\SEGGER\JLinkDevices\Devices\SF32LB55X****.elf

Issue 5: How to Debug LCPU with Ozone

J-Link connects to HCPU by default for debugging.

Solution: To debug LCPU, execute the batch file in a Windows CMD command window: SIFLI-\tools\segger\jlink_lcpu_a0.bat (55), jlink_lcpu_pro.bat (58), jlink_lcpu_56x.bat (56). The batch file executes the commands in \tools\segger\jlink_lcpu_xxx.jlink:

w4 0x4004f000 1
connect
w4 0x40070000 0
exit

You can also enter these two commands directly in the J-Link window to switch to LCPU.