P89LPC9321FN NXP Semiconductors, P89LPC9321FN Datasheet - Page 24

• Manufacturer Part Number: P89LPC9321FN
• Description: MCU 8-Bit 89LP 80C51 CISC 8KB Flash 2.5V/3.3V 28-Pin PDIP Tube
• Manufacturer: NXP Semiconductors

NXP Semiconductors
P89LPC9321_1
Product data sheet
7.13 Memory organization
7.14 Data RAM arrangement
7.15 Interrupts
The various P89LPC9321 memory spaces are as follows:
The P89LPC9321 also has 512 bytes of on-chip data EEPROM that is accessed via SFRs
(see
The 768 bytes of on-chip RAM are organized as shown in
Table 6.
The P89LPC9321 uses a four priority level interrupt structure. This allows great flexibility
in controlling the handling of the many interrupt sources. The P89LPC9321 supports
15 interrupt sources: external interrupts 0 and 1, timers 0 and 1, serial port TX, serial port
RX, combined serial port RX/TX, brownout detect, watchdog/RTC, I
comparators 1 and 2, SPI, CCU, data EEPROM write completion.
Each interrupt source can be individually enabled or disabled by setting or clearing a bit in
the interrupt enable registers IEN0 or IEN1. The IEN0 register also contains a global
disable bit, EA, which disables all interrupts.
Type
DATA
IDATA
XDATA
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•
•
•
•
DATA
128 bytes of internal data memory space (00H:7FH) accessed via direct or indirect
addressing, using instructions other than MOVX and MOVC. All or part of the Stack
may be in this area.
IDATA
Indirect Data. 256 bytes of internal data memory space (00H:FFH) accessed via
indirect addressing using instructions other than MOVX and MOVC. All or part of the
Stack may be in this area. This area includes the DATA area and the 128 bytes
immediately above it.
SFR
Special Function Registers. Selected CPU registers and peripheral control and status
registers, accessible only via direct addressing.
XDATA
‘External’ Data or Auxiliary RAM. Duplicates the classic 80C51 64 kB memory space
addressed via the MOVX instruction using the DPTR, R0, or R1. All or part of this
space could be implemented on-chip. The P89LPC9321 has 512 bytes of on-chip
XDATA memory, plus extended SFRs located in XDATA.
CODE
64 kB of Code memory space, accessed as part of program execution and via the
MOVC instruction. The P89LPC9321 has 8 kB of on-chip Code memory.
Section
On-chip data memory usages
7.14).
Data RAM
Memory that can be addressed directly and indirectly
Memory that can be addressed indirectly
Auxiliary (‘External Data’) on-chip memory that is accessed
using the MOVX instructions
Rev. 01 — 9 December 2008
8-bit microcontroller with accelerated two-clock 80C51 core
Table
P89LPC9321
6.
2
C-bus, keyboard,
© NXP B.V. 2008. All rights reserved.
Size (bytes)
128
256
512
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