General

    The 68hc11 is a powerful 8-bit data, 16-bit address microcontroller
    from Motorola with an instruction set that is similar to the older
    68xx (6801, 6805, 6809) parts.  Depending on the variety, the 68hc11
    has built-in EEPROM/OTPROM, RAM, digital I/O, timers, A/D converter,
    PWM generator, and synchronous and ansynchronous communications
    channels (RS232 and SPI).  Typical current draw is less than 10ma.


    Architecture

    CPU has two 8 bit accumulators (A & B) that can be concatenated to
    provide a 16 bit double accumulator (D).  Two 16 bit index registers
    are present (X,Y) to provide indexing to anywhere in the memory map.
    Having the two index registers means the 68hc11 is very good for
    processing data.  Although an eight bit processor, the 68hc11 has
    some 16 bit instructions (add, subtract, 16 * 16 divide, 8 * 8
    mulitply, shift, and rotates).  A 16 bit stack pointer is also
    present, and instructions are provided for stack manipulation.
    Typically multiplexed address and data bus.


    Onboard subsystems

    Timer -  Main timer system comprises of a single 16 bit counter
    clocked at the E clock (2,3,or 4 Mhz - there is a programmable
    prescaler to slow it down if required). From this single counter run
    a number of input capture and output compare registers (3-4  IC, 5 -
    4 OC). The IC and OC functions are very versatile, and pulses as
    short as 1 E clock can be generated.

    A-D Convertor - Typically 8 channel 8 bit A/D, although the G5 has a
    10 bit A/D.

    Serial Communications Interface (SCI) - Asynchronous serial
    communications; Data format - 1 Start, 8 or 9 data, and one stop bit.
    Data rate - 150 - 312500 Baud (312500 is using 4 mhz E clock)

    Serial Peripheral Interface (SPI) - Synchronous serial
    communications, comprises CLK, DATA IN, DATA OUT and optionally chip
    selects.  As well as using specific SPI devices, it is very easy to
    expand IO using the SPI and standard logic devices (e.g. 74HC595 and
    74HC165).

    The following are Motorola flavors:

    HC11 A Series
       8K ROM (A8), ROMless (A0,A1), 256 RAM, 512 EEPROM (A1,A8), SPI,
       SCI, 3 IC 5 OC, 8 channel 8 bit A/D

    HC11 C0
       Nice new device developed together with AT&T.  ROMless, on board
       bank switching to support memory maps of up to 256K.  Totally
       glueless interface - Chip selects on board, Read Enable and
       Write Enable signals now generated on chip.  256 RAM, 8 channel 8
       bit A/D - Good pricing

    HC11 D Series
       Smallest and lowest cost member of the hc11 Family.  ROMless (D0),
       4K ROM (D3), 4K EPROM (711D3) - No A-D or EEPROM.  Still has
       standard timers and serial ports

    HC11 E Series
       Same as A series execpt 512 bytes RAM and 512 EEPROM (2048 for
       E2).  Pin compatible, only difference is one timer pin (PA4) can
       now be used for IC or OC instect of just OC.  Also have EPROM
       devices and larger memory - hc711e9 (12K OTP), hc711e20 (20K
       OTP)

    HC11 F series
       ROMless, non multiplexed address/data bus with 4 chip selects
       built in.  1K RAM, 512 bytes EEPROM - otherwise same peripherals
       as E series

    HC11 G Series
       16K ROM/EPROM, Non mulitplexed address/data bus, 512 RAM, 4
       channel PWM, 10 Bit A/D convertor, 2 separate 16 bit timers

    HC11 K4
       24K ROM/EPROM, 1Mb addressing using on chip memory mapping.  Non
       multiplexed address and data  bus. 4 programmable chip selects, 8
       channel 8 bit A/D.  4 channel PWM, 768 bytes RAM

    Toshiba second-sources the 68hc11, and they list the following
    variants: A0/A1/A8 and E0/E1/E9.

    For a nice breakdown of the 68hc11 line, check out the file
    taxonomy.txt at cherupakha.media.mit.edu : /pub/miniboard/hobby-tips.
    The file contains a table detailing all of the possible combinations
    that the 68hc11 is supplied in.

    Sources??  Prices??  Hell - you can't even find the suckers!  For
    those of you who remember the old Chicken Man series on radio, "He's
    everywhere! He's everywhere!" - the 68hc11 is not Chicken Man.  The
    68hc11 - "It's nowhere, it's nowhere!"  I remember one episode in
    which our hero was fighting against an evil plot to steal all of the
    refrigerator light bulbs in the world.  Well, maybe the same thing
    happened with the 68hc11 - they just can't be found.

    Maybe it's just a clever scam.  The 68hc11 really doesn't exist.
    Instead, Motorola cobbled together a microprocessor using an Intel
    8051 running an emulation of the 68hc11 instruction set (Intel
    Inside?).

    Ruud Schramp found some in the Netherlands (sounds like an
    appropriate place to find them).  The breakdown is as follows
    (1 US dollar =+- Dfl 1.70):
       Main Importer of Holland   Dfl 15.-- (quantity >100)
       Main Importer of Holland   Dfl 19.-- (if you buy 1 and if they
                                             want to sell 1)
       Distributor                Dfl 25.-- (also no single sales)
       Shop (Display Electronica) Dfl 35.-- (quantity 1)

    Also, the 68hc11 can be found at the following places:

    Active Electronics
       1-800-677-8899

       Some prices from catalog #914:

          68HC11A1FN      13.90
          68HC11A0FN      13.40
          68HC11A1P       18.75
          68HC11A0P       16.40
          68HC11E1FN      17.90
          68HC11F1FN      29.85
          68HC24          18.00 port replacement
          68HCP11A1FN     14.90
          68HCP11A0P      17.90
          68HCP11A1P      20.90
          68HC711D3S      26.90 (OTP)
          68HC711E9FNX    37.50 (OTP)
          68HC711E9FS     44.90 (OTP)
          68HC811E2FN     28.40

          They also sell evaluation boards

    JDR Microdevices
       1850 South 10th Street
       San Jose, CA 95112-4108 USA
       Sales: (800) 538-5000 or (408) 494-1400
       Fax Orders: (800) 538-5005
       Tech Support: (800) 538-5002
       BBS: 408-494-1430

       They list the 68HC11A1P (48 pin DIP version) at $11.95 in their
       1994 electronic component catalog (#37).  They have lots of other
       good stuff in the catalog.  No minimum order.

    Newark Electronics
       Branches throughout the USA, several in Canada, one in U.K.
       One branch at:
       20700 Hubbell Avenue
       Oak Park, MI 48237-0630
       Sales: (313) 967-0600
       Fax: (313) 967-0957

       Catalog number 112 indicates that the carry Motorola micros
       (including the HC11 family.  These guys are big distributors, so
       they can probably get any part in the HC11 family, but they
       probably won't be cheap.

       Prices shown in their 1992 catalog are:

       MC68HC11E0FN (PLCC version) lists at $21.26
       MC68HC11E1FN (PLCC version) lists at $22.36

    B.G. Micro
       P.O.B. 280298
       Dallas, TX  75228
       (214)271-5546

       They usually have a couple varieties at good prices.

      family of microcontrollers

    Traditional architecture - a more traditional architecture than other
    competing products (such as the 8051 and PIC) makes it easier to
    learn and develop on (especially well-suited for teaching
    microcontrollers)

    More features - a 68hc11 is typically a "one-chip" solution since it
    often includes such items as A/D, PWM, and many I/O lines

    Popular - widely used since it is very inexpensive and has a wide
    range of development tools available (both freeware and commercial)