580
Digital Electronics
Yet another mode available with the 80C51 family of microcontrollers that helps in power saving
is the LPEP. The EPROM array contains some analogue circuits that are not required for a V CC
of less than 4.0 V. This feature can be used to save power by setting the LPEP bit, resulting
in reduced supply current. This mode should be used only for applications that require a V CC of
less than 4.0 V.
14.5 Application-Relevant Information
This section briefly presents application-relevant information in terms of general specifications,
microcontroller-related features and peripheral features on some of the common types of microcontroller
from well-known international manufacturers including Intel, Freescale Semiconductor, Microchip
Technology, Altera, Atmel, Zilog, Lattice Semiconductor, National Semiconductor, Applied Micro
Circuits Corporation (AMCC), Fujitsu, Infineon, Dallas Semiconductor, Philips Semiconductors,
Texas Instruments, Xilinx, NEC, Toshiba and so on. Some of the more widely used type numbers,
including the 80C51 family of microcontrollers (Intel and many more manufacturers), the 89C51
microcontroller (Intel and many more manufacturers), the 68HC11 family of microcontrollers
(Freescale Semiconductor) and the PIC 16X84 family of microcontrollers (Microchip Technology),
are discussed in a little more detail. For these type numbers, information such as architecture,
pin connection diagrams, functional description of different pins, addressing modes, etc., is
also presented.
14.5.1 Eight-Bit Microcontrollers
This subsection outlines salient features of popular eight-bit microcontrollers. For most of the type
numbers, the information is contained under two headings, namely microcontroller-related features and
peripheral-related features.
14.5.1.1 80C51/87C51/80C31 (Dallas Semiconductor and Other Manufacturers)
Microcontroller-related Features
MCS-51 architecture, CMOS technology, 4K × 8 ROM (no ROM in 80C31), 128 × 8 RAM, memory
addressing capability of 64K (ROM and RAM), special-function registers, 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) and three package style options (40-pin
dual in-line, 44-pin plastic leaded chip carrier and 44-pin plastic quad flat pack).
Peripheral-related Features
Two 16-bit counters/timers, four eight-bit I/O ports and full duplex-enhanced UART.
Architecture and Pin Connection Diagram
Figure 14.16 shows the architecture and Fig. 14.17 shows the pin connection diagram in the 40-pin
dual in-line package.
Registers
Registers are categorized 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. Registers R0 through R7 are used as scratch-pad registers. In addition, there is
Digital Electronics
Yet another mode available with the 80C51 family of microcontrollers that helps in power saving
is the LPEP. The EPROM array contains some analogue circuits that are not required for a V CC
of less than 4.0 V. This feature can be used to save power by setting the LPEP bit, resulting
in reduced supply current. This mode should be used only for applications that require a V CC of
less than 4.0 V.
14.5 Application-Relevant Information
This section briefly presents application-relevant information in terms of general specifications,
microcontroller-related features and peripheral features on some of the common types of microcontroller
from well-known international manufacturers including Intel, Freescale Semiconductor, Microchip
Technology, Altera, Atmel, Zilog, Lattice Semiconductor, National Semiconductor, Applied Micro
Circuits Corporation (AMCC), Fujitsu, Infineon, Dallas Semiconductor, Philips Semiconductors,
Texas Instruments, Xilinx, NEC, Toshiba and so on. Some of the more widely used type numbers,
including the 80C51 family of microcontrollers (Intel and many more manufacturers), the 89C51
microcontroller (Intel and many more manufacturers), the 68HC11 family of microcontrollers
(Freescale Semiconductor) and the PIC 16X84 family of microcontrollers (Microchip Technology),
are discussed in a little more detail. For these type numbers, information such as architecture,
pin connection diagrams, functional description of different pins, addressing modes, etc., is
also presented.
14.5.1 Eight-Bit Microcontrollers
This subsection outlines salient features of popular eight-bit microcontrollers. For most of the type
numbers, the information is contained under two headings, namely microcontroller-related features and
peripheral-related features.
14.5.1.1 80C51/87C51/80C31 (Dallas Semiconductor and Other Manufacturers)
Microcontroller-related Features
MCS-51 architecture, CMOS technology, 4K × 8 ROM (no ROM in 80C31), 128 × 8 RAM, memory
addressing capability of 64K (ROM and RAM), special-function registers, 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) and three package style options (40-pin
dual in-line, 44-pin plastic leaded chip carrier and 44-pin plastic quad flat pack).
Peripheral-related Features
Two 16-bit counters/timers, four eight-bit I/O ports and full duplex-enhanced UART.
Architecture and Pin Connection Diagram
Figure 14.16 shows the architecture and Fig. 14.17 shows the pin connection diagram in the 40-pin
dual in-line package.
Registers
Registers are categorized 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. Registers R0 through R7 are used as scratch-pad registers. In addition, there is