Innovation Center: Linux Cross Assemblers

Sunday, July 31, 2011

Linux Cross Assemblers

Motorola/Freescale 680X/6811 cross assemblers for Unix/Linux

Masm is a modification of the Motorola DOS freeware assembler that works on UNIX/Linux environments. This assembler package supports the following microprocessors: 6800, 6801, 6804, 6805, 6809, and 68HC11. I have added command line arguments to allow generation of Intel Hex files and a 64K binary image format in addition to the default Motorola S records. A variety of EPROM programmers are thus supported.

Buf is a utility that allows a Unix/Linux machine to download S record files directly to the Buffalo monitor program that is found on the Motorola 6811EVM development board. Buf is distributed under the Gnu GPL license.

The microprocessor break reset circuit below is required for fully automatic operation of buf. The circuit allows buf to reset a running program and jump into the Buffalo monitor program by detecting a break signal on the serial line. This speeds up the code testing cycle and allows the 68HC11 to be in a remote location. This circuit has allowed software to be developed on a microprocessor system that was sitting hundreds of miles away across the internet, connected to a Unix machine’s serial port.

An example 68HC11 assembly language program is included as a useful starting point. This code makes use of the Unix Gnu C preprocessor and #define statements so that both the RAM based BUFFALO version and the EPROM based version can be built from a single assembly language file.