GRMON3 is a hardware monitor optimized for SPARC/LEON and RISC-V/NOEL-V systems, providing a non-intrusive debug environment. The target system can be monitored and controlled by the graphical user interface with scripting support. A large number of debug link interfaces are supported and the debugger can be user adapted for several system configurations.

GRMON3 has full support for multi-core systems, such as the GR740 Quad-Core LEON4 SPARC V8 Processor GR740 device, the dual-core GR712RC and NOEL-V demonstration FPGA bitstreams.


  • Read/write access to all LEON and NOEL-V registers and memory
  • Execution control with support for multiple CPUs and OS threads
  • Built-in disassembler and trace buffer management
  • Breakpoint and watchpoint management
  • Command-line mode
  • Remote connection to GNU debugger (GDB)
  • Auto-probing and initialization of LEON or NOEL-V peripherals and memory settings
  • Error injection for fault-tolerant LEON processors
  • Supported debug interfaces: USB, Ethernet, JTAG, UART and SpaceWire
  • Common Flash Interface (CFI) compatible Flash PROM programming
  • Tcl scripting support
    • All GRMON commands are Tcl commands
    • Custom commands and device drivers can be implemented by the user
    • Hooks for installing custom handlers executed on certain events
    • Peripheral device register bits available as Tcl variables
    • TAB-completion on Tcl variables, procedures, file names etc.
  • In-application help for all commands
  • Context-based virtual memory handling
  • Translates virtual addresses for GDB, e.g. it's possible to debug the VxWorks/Linux kernel

Graphical User Interface

The GRMON3 GUI greatly extends the traditional monitoring and control capabilities of GRMON:

  • Debug-link and system configuration dialog
  • Multi-core LEON/RISC-V and OS threads execution status and backtrace view
  • Disassembly view with symbol and breakpoint information
  • Breakpoints view for managing breakpoints and watchpoints
  • Memory, CPU register and I/O register inspection and edit views
  • Optimized SPARC/LEON and RISC-V/NOEL-V IU register view
  • C/C++ source level debugging including source code view, stepping and line breakpoints
  • Variables and expressions views.
  • Application launch dialog
  • Tcl terminal views with history, tab-completion, etc.
  • Application terminals via UART forwarding
  • GRLIB SOC system hardware overview

Supported target devices

Supported platforms and system requirements

GRMON3 is provided for platforms: Linux, Windows 7 and Windows 10.

Documentation and download

GRMON3 User's Manual is available on-line.

Professional and evaluation versions of GRMON3 for Linux and Windows can be obtained from the download page.