Rainbow Electronics DS89C450 - Manual (Page 14)

DS89C430/DS89C440/DS89C450 Ultra-High-Speed Flash Microcontrollers
14 of 48
Figure 5. Functional Diagram
CONTROL
AND
SEQUENCER
INTERNAL
REGISTERS
DECODER
IR
INTERRUPT
CPU
SERIAL I/O TIMER/
COUNTERS
1kB x 8
RAM
16kB/32kB
64kB x 8
FLASH
I/O PORTS
SFRs
DPTR
DPTR1
SP
PC
AR INC
AR
WATCHDOG TIMER
AND
POWER MANAGER
CLOCK
AND
RESET
MEMORY
CONTROL
ROM
LOADER
XT
AL
2
XT
AL
1
RST
P
SEN
E
A
ALE/
PR
O
G P0 P1 P2 P3
ADDRESS BUS
INTERNAL CONTROL BUS
DETAILED DESCRIPTION
The DS89C430, DS89C440, and DS89C450 are pin compatible with all three packages of the standard 8051 and
include standard resources such as three timer/counters, serial port, and four 8-bit I/O ports. The three part
numbers vary only by the amount of internal flash memory (DS89C430 = 16kB, DS89C440 = 32kB, DS89C450 =
64kB), which can be in-system/in-application programmed from a serial port using ROM-resident or user-defined
loader software. For volume deployments, the flash can also be loaded externally using standard commercially
available parallel programmers.
Besides greater speed, the DS89C430/DS89C440/DS89C450 include 1kB of data RAM, a second full hardware
serial port, seven additional interrupts, two extra levels of interrupt priority, programmable watchdog timer,
brownout monitor, and power-fail reset. Dual data pointers (DPTRs) are included to speed up block data-memory
moves with further enhancements coming from selectable automatic increment/decrement and toggle select
operation. The speed of MOVX data memory access can be adjusted by adding stretch values up to 10 machine
cycles for flexibility in selecting external memory and peripherals.
A power management mode consumes significantly lower power by slowing the CPU execution rate from one clock
period per cycle to 1024 clock periods per cycle. A selectable switchback feature can automatically cancel this
mode to enable normal speed responses to interrupts.
For EMI-sensitive applications, the microcontroller can disable the ALE signal when the processor is not accessing
external memory.
Dallas Semiconductor
DS89C430/DS89C440/
DS89C450