Central Processing Unit

The Central Processing Unit (CPU) processes information in accordance with a program of instructions and data in a particular language called "machine code". The CPU controls all the system operations and provides control signals for enabling and disabling the various peripherals and I/O devices.

The 68HC05 CPU core is the most popular 8-bit microcontroller architecture in the world with well over 1 BILLION units shipped. The accumulator based HC05 CPU is a relatively easy to program and understand architecture. In addition to the accumulator, the CPU's core has an index register, a 5-bit stack pointer, and a 5-bit condition code register. The instruction set features 10 uncomplicated addressing modes including 8 and 16-bit indexing from the 16-bit program counter. Bit manipulation instructions are provided to set, clear, test, or jump based on a bit value anywhere in the memory map. Math functions include add, subtract, and multiply.

The HC05 CPU is a fully static low power HCMOS design that features flexible power management capabilities. Wait mode reduces power consumption by approximately 50% by discontinuing CPU processing. The clock continues to run in wait mode inorder to service interrupts immediately. Stop mode stops the clock and all internal processing to reduce power consumption to micoroamps. Both modes maintain memory and enable an interrupt to wake up the CPU.