Freescale 68HC08
Encyclopedia
The 68HC08 is a broad family of 8-bit
microcontroller
s from Freescale Semiconductor
(formerly Motorola
Semiconductor).
HC08's are fully code-compatible with their predecessors, the Motorola 68HC05
. Like all Motorola processors that share lineage from the 6800
, they use the von Neumann architecture
as well as memory-mapped I/O. This family has five CPU register
s that are not part of the memory. One 8-bit accumulator
A, a 16-bit index register
H:X, a 16-bit stack pointer SP, a 16-bit program counter
PC, and an 8-bit condition code register CCR. Some instructions refer to the different bytes in the H:X index register independently.
Among the HC08's there are dozens of processor families, each targeted to different embedded applications. Features and capabilities vary widely, from 8 to 64-pin processors, from USB 1.1 connectivity to LIN
.
The Freescale RS08 core is a simplified, "reduced-resource" version of the HC08.
The Freescale HCS08
core is the next generation of the same processors.
8-bit
The first widely adopted 8-bit microprocessor was the Intel 8080, being used in many hobbyist computers of the late 1970s and early 1980s, often running the CP/M operating system. The Zilog Z80 and the Motorola 6800 were also used in similar computers...
microcontroller
Microcontroller
A microcontroller is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory in the form of NOR flash or OTP ROM is also often included on chip, as well as a typically small amount of RAM...
s from Freescale Semiconductor
Freescale Semiconductor
Freescale Semiconductor, Inc. is a producer and designer of embedded hardware, with 17 billion semiconductor chips in use around the world. The company focuses on the automotive, consumer, industrial and networking markets with its product portfolio including microprocessors, microcontrollers,...
(formerly Motorola
Motorola
Motorola, Inc. was an American multinational telecommunications company based in Schaumburg, Illinois, which was eventually divided into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011, after losing $4.3 billion from 2007 to 2009...
Semiconductor).
HC08's are fully code-compatible with their predecessors, the Motorola 68HC05
Motorola 68HC05
The 68HC05 is a broad family of 8-bit microcontrollers from Freescale Semiconductor .Like all Motorola processors that share lineage from the 6800, they use the von Neumann architecture as well as memory-mapped I/O. This family has five CPU registers that are not part of the memory...
. Like all Motorola processors that share lineage from the 6800
Motorola 6800
The 6800 was an 8-bit microprocessor designed and first manufactured by Motorola in 1974. The MC6800 microprocessor was part of the M6800 Microcomputer System that also included serial and parallel interface ICs, RAM, ROM and other support chips...
, they use the von Neumann architecture
Von Neumann architecture
The term Von Neumann architecture, aka the Von Neumann model, derives from a computer architecture proposal by the mathematician and early computer scientist John von Neumann and others, dated June 30, 1945, entitled First Draft of a Report on the EDVAC...
as well as memory-mapped I/O. This family has five CPU register
Processor register
In computer architecture, a processor register is a small amount of storage available as part of a CPU or other digital processor. Such registers are addressed by mechanisms other than main memory and can be accessed more quickly...
s that are not part of the memory. One 8-bit accumulator
Accumulator (computing)
In a computer's central processing unit , an accumulator is a register in which intermediate arithmetic and logic results are stored. Without a register like an accumulator, it would be necessary to write the result of each calculation to main memory, perhaps only to be read right back again for...
A, a 16-bit index register
Index register
An index registerCommonly known as a B-line in early British computers. in a computer's CPU is a processor register used for modifying operand addresses during the run of a program, typically for doing vector/array operations...
H:X, a 16-bit stack pointer SP, a 16-bit program counter
Program counter
The program counter , commonly called the instruction pointer in Intel x86 microprocessors, and sometimes called the instruction address register, or just part of the instruction sequencer in some computers, is a processor register that indicates where the computer is in its instruction sequence...
PC, and an 8-bit condition code register CCR. Some instructions refer to the different bytes in the H:X index register independently.
Among the HC08's there are dozens of processor families, each targeted to different embedded applications. Features and capabilities vary widely, from 8 to 64-pin processors, from USB 1.1 connectivity to LIN
Local Interconnect Network
The LIN-Bus is a vehicle bus standard or computer networking bus-system used within current automotive network architectures....
.
The Freescale RS08 core is a simplified, "reduced-resource" version of the HC08.
The Freescale HCS08
Freescale S08
The 9S08 is a 8-bit microcontroller family originally from Motorola, now produced by Freescale Semiconductor, descended from the Motorola 6800 microprocessor. It is a CISC microcontroller. The 9S08 devices are more powerful and usually less expensive than the aging 68HC05 microcontrollers, and...
core is the next generation of the same processors.