DS2251T Datasheet, PDF (1/19 Pages) Dallas Semiconductor – 128K Soft Microcontroller Module

DS2251T
DS2251T
128K Soft Microcontroller Module
FEATURES
• 8051 compatible microcontroller adapts to its task
– 32K, 64K, or 128K bytes of nonvolatile SRAM
for program and/or data storage
– In–system programming via on–chip serial port
– Capable of modifying its own program or data
memory in the end system
– Provides separate Byte–wide bus for peripherals
– Performs CRC–16 check of NVRAM memory
• High–reliability Operation
– Maintains all nonvolatile resources for over 10
years in the absence of power
– Power–fail reset
– Early Warning Power–fail Interrupt
– Watchdog Timer
– Lithium backed memory remembers system
state
– Precision reference for power monitor
• Fully 8051 Compatible
– 128 bytes scratchpad RAM
– Two timer/counters
– On–chip serial port
– 32 parallel I/O port pins
• Permanently powered real time clock
DESCRIPTION
The DS2251T is an 8051 compatible microcontroller
module based on nonvolatile RAM technology. It is
designed for systems that need large quantities of non-
volatile memory. Like other members of the Secure
Microcontroller family, it provides full compatibility with
the 8051 instruction set, timers, serial port, and parallel
I/O ports. By using NVRAM instead of ROM, the user
can program, then reprogram the microcontroller while
in–system. The application software can even change
its own operation. This allows frequent software
upgrades, adaptive programs, customized systems,
etc. In addition, by using NVRAM, the DS2251T is ideal
PACKAGE OUTLINE
72–PIN SIMM
for data logging applications. The powerful real time
clock includes interrupts for time stamp and date. It
keeps time to one hundredth of second using its on–
board 32 KHz crystal.
The DS2251T provides the benefits of NVRAM without
using I/O resources. Between 32K bytes and 128K
bytes of on–board NVRAM are available. A non–multi-
plexed Byte–wide address and data bus is used for
memory access. This bus, which is available at the con-
nector, can perform all memory access and also pro-
vides decoded chip enables for off–board memory
ECopyright 1995 by Dallas Semiconductor Corporation.
All Rights Reserved. For important information regarding
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