INTRODUCTION

The 68HC11 is a powerful 8-bit data, 16-bit address microcontroller from Motorola with an instruction set that is similar to the previous 68xx (6801, 6805, 6809) microcontrollers. Depending on the variety, the 68HCll has built-in EEPROM/OTPROM, RAM, digital I/O, timers, ND converter, PWM generator and synchronous and asynchronous communications channels (RS232 and Serial Peripheral Interface (SPI)). Typical current draw is less than 20ma.

68HC11 SERIES OF MICROCONTROLLERS

The MC68HCll family has many versions described as follows:
HC11A series microcontrollers
8K ROM (A8), ROMless (A0, A1), 256 RAM, 512 EEPROM (A1, A8), SPI,
SCI, 3 IC 5 OC, 8 channel 8 bit A/D

HC11C0 microcontrollers
ROMless, on board bank switching to support memory maps up to 256K. Chip selects on board, on chip Read Enable and Write Enable signals, 256 RAM, 8 channel 8 bit A/D. BC11D series microcontrollers

HC11D microcontrollers
Smallest and cheapest member of the hc11 Family. ROMless (D0), 4K ROM (D3), 4K EPROM (7llD3)-No A/D or EEPROM, but has standard timers and serial ports. 

HC11E series microcontrollers
Same as A series except 512 bytes RAM and 512 EEPROM (2048 for E2). Pin compatible, only difference is one timer pin (PA4) can be used for IC or OC instead of just OC. Also have EPROM devices and larger memory-hc7lle9 (12K OTP), hc7lle20 (20K OTP).

HC11F series microcontrollers
ROMless, non-multiplexed address/data bus with 4 chip selects built in. 1K RAM, 512 bytes EEPROM, same peripherals as E series.

HC11G series microcontrollers
16K ROM/EPROM, Non multiplexed address/data bus, 512 RAM, 4 channel PWM, 10 Bit ND converter, 2 separate 16 bit timers.

HC11K4 microcontroller
24K ROM/EPROM, 1Mb addressing using on chip memory mapping. Non-multiplexed address and data bus. 4 programmable chip selects, S channel 8 bit A/D. 4 channel PWM, 768 bytes RAM.

Several of the microcontrollers within the M68HC11 family have 'x1' and 'x0' versions. These are identical to the main member of the series but have some of their on-chip functions disabled. For example, MC68HC11A1 is identical to the MC68HC11A8 except that its ROM is disabled. An MC68HC11A0 has disabled EPROM and EEPROM arrays.

Normally all series within the M68HC11 family have both a ROM version and an EPROM version. Any device in the M68HC11 family that has a 7 preceding the 11 is a device containing EPROM instead of ROM (e.g., MC68HC711E9). These devices operate exactly as the ROM based version (e.g., MC68HCllE9) but can be programmed by the user. EPROM-based devices in a windowed package can be erased and reprogrammed. While EPROM-based devices in standard packages are one-time-programmable (OTP).