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Open Picoblaze Assembler

Project description

Open PicoBlaze Assembler

Opbasm is a free cross-platform assembler for the PicoBlaze-3 (PB3) and PicoBlaze-6 (PB6) microcontrollers provided by Xilinx. It will run readily on any platform with a Python interpreter. Opbasm provides a better performing solution to assembling PicoBlaze code without resorting to DOS or Windows emulation to run the native KCPSM assemblers.

Special features of Opbasm:

  • Optional m4 preprocessor macros are available when the m4 program is installed. An extensive set of built-in macros provide more advanced features than the base language. For example, converting temperature scales becomes as easy as this:

reg16(rx, s4,s5)                ; Create a virtual 16-bit register pair named rx

  load reglower(rx), s0         ; Load 8-bit Celsius temperature into low byte
  signex(rx)                    ; Sign extend to 16-bits
  expr2s(rx := rx * 9 / 5 + 32) ; Perform 16x8-bit signed arithmetic to get Fahrenheit

Support for the full PicoBlaze-6 syntax is provided as well as enabling most of the new PB6 syntax enhancements in PicoBlaze-3 code. The original templating system for ROM components is supported as well as a more flexible generic ROM component that can read .mem and .hex files directly during synthesis and simulation. A utility script is included that permits updating the ROM contents of a bitstream file without requiring resynthesis as was formerly supplied by the DOS-based KCPSM3 tools.

Files generated on non-Windows platforms will not have DOS line endings and PicoBlaze-3 files are not restricted to 8.3 file names. Opbasm also runs significantly faster than the native implementation:


Opbasm requires either Python 2.7 or Python 3.x and no additional libraries. The installation script depends on setuptools which will be installed if it isn’t currently present in your Python distribution. Optional macro support is provided when m4 is installed. You can get optional colorized output from the scripts by installing the Python colorama package. The source is written in Python 2.7 syntax but will convert cleanly to Python 3 when the installer passes it through 2to3.


You can access the Opbasm Git repository from Github. Packaged source code is also available for download. You can install direct from PyPI with the “pip” command if you have it available.


The full documentation is available online at the main Opbasm site.

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