DS2250(T)
Soft Microcontroller Module
DS2250(T)
Copyright 1995 by Dallas Semiconductor Corporation.
All Rights Reserved. For important information regarding
patents and other intellectual property rights, please refer to
Dallas Semiconductor data books.
121395 1/19
FEATURES
• 8–bit 8051 compatible microcontroller adapts to task–
at–hand:
– 8K, 32K, or 64K bytes of nonvolatile RAM for
program and/or data memory storage
– Initial downloading of software in end system
via on–chip serial port
– Capable of modifying its own program and/or
data memory in end use
• High–reliability operation:
– Maintains all nonvolatile resources for 10 years
in the absence of V
CC
– Power–fail reset
– Early warning power–fail interrupt
– Watchdog timer
• Software Security Feature:
– Executes encrypted software to prevent unau-
thorized disclosure
• On–chip, full–duplex serial I/O ports
• Two on–chip timer/event counters
• 32 parallel I/O lines
• Compatible with industry standard 8051 instruction
set
• Permanently Powered real time clock
PIN ASSIGNMENT
40-PIN SIMM
1202140
DESCRIPTION
The DS2250(T) Soft Microcontroller Module is a fully
8051 compatible 8–bit CMOS microcontroller that offers
“softness” in all aspects of its application. This is ac-
complished through the comprehensive use of nonvola-
tile technology to preserve all information in the ab-
sence of system V
CC
. The internal program/data
memory space is implemented using 8K, 32K, or 64K
bytes of nonvolatile CMOS SRAM. Furthermore, inter-
nal data registers and key configuration registers are
also nonvolatile. An optional real time clock gives per-
manently powered timekeeping. The clock keeps time
to a hundredth of a second using an on–board crystal.
All nonvolatile memory and resources are maintained
for over 10 years at room temperature in the absence of
power.
