Bootstrap Examples

These examples are very small and they are designed to fit in less than 256 bytes (less than 240 to leave room for the stack). They represent typical programs that can be uploaded during the 68HC11 bootstrap mode.

• Hello World Tutorial for 68HC11 bootstrap mode
• Blink program for a Christmas tree.
• Simple Hello World for 68HC11 bootstrap mode
• External RAM booter.
• Check the memory and return the target board memory layout.
• Dump the content of memory.
• Internal Eprom loader and burner.

In general to compile and link these programs, you will use the following command:

      m6811-elf-gcc -o file.elf -nostdlib -nostartfiles \
		    -Wl,-defsym,_io_ports=0x1000 \
		    -Wl,-defsym,_.tmp=0x0 -Wl,-defsym,_.z=0x2 \
		    -Wl,-m,m68hc11elfb \
		    -mshort -Os -fomit-frame-pointer -msoft-reg-count=0 \
		    file.c
    

In this cryptic and long command, the following options are used by the compiler:

-mshort	This option tells gcc to use 16-bit integers.
-Os	This option tells gcc to optimize for size.
-fomit-frame-pointer	This option tells gcc to remove the frame pointer.
-msoft-reg-count=0	This option tells gcc to avoid to use soft registers (except _.tmp and _.z which are sometimes necessary)

And the following options are used by the linker:

-nostdlib	The standard libraries are not passed to the linker.
-nostartfiles	The standard startup files are not used during the link.
-defsym _io_ports=0x1000	The linker will define the symbol _io_ports and assign it the value 0x1000. This symbol is used by the examples to access the 68HC11 registers.
-defsym _.tmp=0x0 -defsym _.z=0x0	This will define the symbol _.tmp used by gcc.