Main Features of 80C51, 87C51 and 80C31 Microcontrollers

All these three types of microcontrollers are 8-bit manufactured by NXP semiconductors with embedded Intel processors.

Some of the key features of these microcontrollers are listed in the following sections but it is important to note that, you can get the full and latest details on each of the specific device from the official documentation.

Microcontroller & Peripheral Related Features

The key features of these microcontrollers include:

• They all have MCS-51 architecture.
• They are based on CMOS technology.
• Have 4K x 8 ROM (no ROM in 80C31).
• 128 x 8 RAM.
• Memory addressing capability of 64K (ROM and RAM).
• Special function registers (SFRs).
• Six interrupt sources.
• Three power control modes including STOP CLOCK, IDLE and POWER DOWN modes.
• Two clock speed ranges of 0-16 MHz and 0-33 MHz.
• Low EMI (inhibit ALE).
• Three package style options (40-pin dual in-line, 44-pin plastic leaded chip carrier and 44-pin plastic quad flat pack).
• Two 16-bit counters/timers, four eight-bit I/O ports and full duplex-enhanced UART.

Architecture and Pin Connection Diagram

The following figures below shows the architecture and pin connection in the 40-pin dual in-line package.

Architecture:

Pin Connection

Registers

Registers are classified as general purpose registers and special function registers. The 80C51 family of microcontrollers has an accumulator, B-register and four register banks, each having eight-bit wide registers R0 to R7. The registers R0 to R7 are used as scratch-pad registers. Additionally, there is an eight-bit wide stack pointer and a 16-bit wide program counter. Special function registers include program status word (PSW), data pointer (DPTR), timer registers, control registers and capture registers.

Related article: CPU Registers

Addressing Modes

The 80C51 family of microcontrollers, supports five addressing modes including register addressing, register direct addressing, register indirect addressing, immediate addressing and base register plus index register addressing.

Related: 6 Types of Microprocessor Addressing Modes

Power Modes

The 80C51 family of microcontrollers provides a variety of operational modes that can be used to reduce power consumption. These include STOP CLOCK MODE which enables the clock speed to be reduced down to 0 MHz, IDLE MODE when the CPU puts itself to sleep while all of the on-chip peripherals stay active and POWER DOWN MODE in which the oscillator is stopped. Additionally to the power saving operational modes, it also provides ONCE^TM (On-Circuit Emulation) MODE which facilitates in-circuit testing and debugging.

Interrupts

The 80C51 family of microcontrollers supports five factored interrupts. These include external interrupt 0, external interrupt 1, timer/counter 0 interrupt, timer/counter 1 interrupt and serial port interrupts.

Related articles:

• The Basic Structure of Intel 8051 Microcontroller
• The MOV Instruction in Intel 8051 (MCS-51) Microcontroller
• How to Interface PIC Microcontroller to Input & Output Devices
• The Intel 8085 Microprocessor
• How a Microcontroller can be used in a Temperature Measurement System