• 68HC11

Motorola 68HC11

The 68HC11 is an "old" Motorola microcontroller. Despite its age, it refuses to go away and there is still an active development community around it. Perhaps the reason for its longevity is the wide suite of development and support tools and hardware that exist for the 68HC11.

Some things that make the 68HC11 "old" are:

• It's not easily reprogrammable (unlike today's modern FLASH chips).
• It's relatively slow (maximum internal clock frequency is 2 MHz, or 3 MHz on some unique parts).
• Each instruction takes several cycles (unlike today's modern single-instruction-cycle RISC microcontrollers). The MUL (multiply) instruction, for example, takes a whopping 41 cycles.
• The device pins cannot source or sink enough current to turn on LED's, for example.
• It's either too big or too small. The "one size fits all" 68HC11 is either too small for a given project (not enough pins, for example) or is too big (52-pin package?!) when a much smaller microcontroller would do. Today's microcontroller families come with a wide variety of "sub-species" that let you choose just the right chip for the job.

Motorola followed up the 8-bit 68HC11 with the 16-bit 68HC12, which is backwards compatible with the 68HC11 but is a "big" chip in a TQFP package, making it hobbyist-unfriendly. Perhaps a better migration path from the 68HC11 is Motorola's 8-bit ["68HC908"] series of microcontrollers.

Here are some resource links:

• [http://www.axman.com Axiom Manufacturing] makes the [http://www.axman.com/Pages/neuprod8_cmm11e1.html CMM-11E1] boards that we currently use to power the Wallace robots in EGR226 and the [http://www.axman.com/Pages/neuprod8_cme11e9.html CME-11E9] boards that are used for laboratories in EGR345 and EGR424.

• [http://www.axman.com/files/MC68HC11/CMM-11A8-E9/doc/cmm11.PDF CMM-11E1 User Manual] [41KB]

• [http://www.axman.com/files/MC68HC11/CME-11E9-EVBU/doc/Manuals/CME11E9-EVBU-m.pdf CME-11E9 User Manual] [118KB]

• Motorola's [http://e-www.motorola.com/webapp/sps/site/taxonomy.jsp?nodeId=03t3ZGpnLn84498635 M68HC11 Family page]

• [http://e-www.motorola.com/files/microcontrollers/doc/data_sheet/M68HC11E.pdf 68HC11 Technical Data] Rev. 5

• [http://e-www.motorola.com/files/microcontrollers/doc/ref_manual/M68HC11ERG.pdf 68HC11 Programming Reference Guide] Rev. 1

• [http://e-www.motorola.com/files/microcontrollers/doc/ref_manual/M68HC11RM.pdf 68HC11 Reference Manual] Rev. 6