M68HC11
REFERENCE MANUAL
PINS AND CONNECTIONS
MOTOROLA
2-1
SECTION 2
PINS AND CONNECTIONS
This section discusses the functions of each pin on the MC68HC11A8. Most pins on
this microcontroller unit (MCU) serve two or more functions. Information about the
practical use of each pin is presented in these pin descriptions. This section also in-
cludes information concerning pins that are exposed to illegal levels or conditions. The
most common source of illegal levels or conditions is transient noise; however, a de-
signer may wish to take precautions against potential misapplication of a product or
failures of other system components such as power supplies. Consideration of these
factors can influence end-product reliability.
The basic connections for single-chip-mode and expanded-mode applications are pre-
sented in
2.5 Typical Single-Chip-Mode System Connections
and
2.6 Typical Ex-
panded-Mode-System Connections
. These basic systems can be used as the
starting point for any user application and can minimize the time required to achieve a
working prototype system. The explanation of these basic systems includes informa-
tion concerning additions, such as additional memory on the expanded system.
System noise generation and susceptibility primarily depend on each system and its
environment. The MC68HC11A8 is designed for higher bus speeds than earlier
MCUs; since it is high-density complementary metal-oxide semiconductor (HCMOS),
signals drive from rail to rail, unlike earlier N-channel metal-oxide semiconductor
(NMOS) processors. Since these factors can significantly affect noise issues, the sys-
tem designer should consider these changes.
2.1 Packages And Pin Names
The following figures show pin assignments for several members of the M68HC11
MCU Family. The pin assignments for the MC68HC24 port replacement unit (PRU)
are also presented for reference although the PRU is not discussed in detail in this
manual.
Detailed mechanical data for packages may be found in the data sheets or technical
summaries. Ordering information, which relates part number suffixes to package types
and operating temperature range, are also found in the data sheets or technical sum-
maries.
2.1.1 MC68HC11A8
The MC68HC11A8 is available in either a 52-pin plastic leaded chip carrier (PLCC)
package or a 48-pin dual-in-line package (DIP). The silicon die is identical for both
packages, but four of the analog-to-digital (A/D) converter inputs are not bonded out
to pins in the 48-pin DIP. The MC68HC11A1 and MC68HC11A0 devices also use the
same die as the MC68HC11A8, except that the contents of the nonvolatile CONFIG
register determine whether or not internal read-only memory (ROM) and/or electrically