Since the introduction of the MC68HCIIA8 microcontroller in 1984, the family has grown to more than a dozen primary derivatives and nearly 100 million units have been sold. Today there are versions of the MC68HC11 with ROM, RAM, EPROM and EEPROM on a single device.
Other major peripheral systems on M68HC11 family members include 8-bit and 10-bit analog to digital (A/D) converters, two types of serial I/O systems, complex timers, a pulse accumulator (event counter), PWM timers, handshake parallel I/O, flexible chip selects and system protection circuits. Bus speeds have increased to 4 MHz on some versions, there are now non-multiplexed bus versions, and a version that allows for more than a megabyte of address space is available. Several OTP and EPROM versions are also available.
This paper looks beyond the obvious uses of the MC68HC11 and its on-chip peripherals to investigate some of the less apparent aspects of this powerful MCV. Practices which can help to avoid application difficulties are also be discussed.