Introduction
This document contains a detailed description of the M68HC11 E series of 8-bit microcontroller units (MCUs). These MCUs all combine the M68HC11 central processor unit (CPU) with high-performance, on-chip peripherals.
The E series is comprised of many devices with various configurations of:

• Random-access memory (RAM)
• Read-only memory (ROM)
• Erasable programmable read-only memory (EPROM)
• Electrically erasable programmable read-only memory (EEPROM)
• Several low-voltage devices are also available.
With the exception of a few minor differences, the operation of all E-series MCUs is identical. A fully static design and high-density complementary metal-oxide semiconductor (HCMOS) fabrication process allow the E-series devices to operate at frequencies from 3 MHz to dc with very low power consumption.

FEATUREs
Features of the E-series devices include:
• M68HC11 CPU
• Power-saving stop and wait modes
• Low-voltage devices available (3.0–5.5 Vdc)
• 0, 256, 512, or 768 bytes of on-chip RAM, data retained during standby
• 0, 12, or 20 Kbytes of on-chip ROM or EPROM
• 0, 512, or 2048 bytes of on-chip EEPROM with block protect for security
• 2048 bytes of EEPROM with selectable base address in the MC68HC811E2
• Asynchronous non-return-to-zero (NRZ) serial communications interface (SCI)
• Additional baud rates available on MC68HC(7)11E20
• Synchronous serial peripheral interface (SPI)
• 8-channel, 8-bit analog-to-digital (A/D) converter
• 16-bit timer system:
   – Three input capture (IC) channels
   – Four output compare (OC) channels
   – One additional channel, selectable as fourth IC or fifth OC
• 8-bit pulse accumulator
• Real-time interrupt circuit
• Computer operating properly (COP) watchdog system
• 38 general-purpose input/output (I/O) pins:
   – 16 bidirectional I/O pins
   – 11 input-only pins
   – 11 output-only pins
• Several packaging options:
   – 52-pin plastic-leaded chip carrier (PLCC)
   – 52-pin windowed ceramic leaded chip carrier (CLCC)
   – 52-pin plastic thin quad flat pack, 10 mm x 10 mm (TQFP)
   – 64-pin quad flat pack (QFP)
   – 48-pin plastic dual in-line package (DIP), MC68HC811E2 only
   – 56-pin plastic shrink dual in-line package, .070-inch lead spacing (SDIP)