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.


The TSIM3 simulator and the GRMON3 debugger share a powerful scripting framework based on Tcl. Tcl scripts can adapt to minor differences in the respective Tcl environments so that the same script can be used in both TSIM3 and GRMON3. This enables users to easily transition from the simulation environment to real hardware validation, considerably reducing development time and improving overall productivity.

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.