UPSD3254 STMICROELECTRONICS [STMicroelectronics], UPSD3254 Datasheet - Page 18

• Manufacturer Part Number: UPSD3254
• Description: Flash Programmable System Devices with 8032 Microcontroller Core
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

UPSD3254A, UPSD3254BV, UPSD3253B, UPSD3253BV
ARCHITECTURE OVERVIEW
Memory Organization
The uPSD325X devices’ standard 8032 Core has
separate 64KB address spaces for Program mem-
ory and Data Memory. Program memory is where
the 8032 executes instructions from. Data memory
is used to hold data variables. Flash memory can
be mapped in either program or data space. The
Flash memory consists of two flash memory
blocks: the main Flash (1 or 2Mbit) and the Sec-
ondary Flash (256Kbit). Except during flash mem-
ory programming or update, Flash memory can
only be read, not written to. A Page Register is
used to access memory beyond the 64K bytes ad-
dress space. Refer to the PSD Module for details
on mapping of the Flash memory.
Figure 5. Memory Map and Address Space
Registers
The 8032 has several registers; these are the Pro-
gram Counter (PC), Accumulator (A), B Register
(B), the Stack Pointer (SP), the Program Status
Word (PSW), General purpose registers (R0 to
R7), and DPTR (Data Pointer register).
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SECONDARY
FLASH
32KB
Flash Memory Space
MAIN
FLASH
128KB
256KB
OR
FF
7F
0
INT. RAM
Addressing
Addressing
Indirect
Indirect
Direct
Internal RAM Space
(256 Bytes)
or
SFR
Addressing
Direct
The 8032 core has two types of data memory (in-
ternal and external) that can be read and written.
The internal SRAM consists of 256 bytes, and in-
cludes the stack area.
The SFR (Special Function Registers) occupies
the upper 128 bytes of the internal SRAM, the reg-
isters can be accessed by Direct addressing only.
There are two separate blocks of external SRAM
inside the uPSD325X devices: one 256 bytes
block is assigned for DDC data storage. Another
32K bytes resides in the PSD Module that can be
mapped to any address space defined by the user.
Figure 6. 8032 MCU Registers
DPTR(DPH)
PCH
FFFF
FF00
EXT. RAM
(DDC)
DPTR(DPL)
External RAM Space
(MOVX)
256B
R0-R7
PSW
PCL
SP
A
B
EXT. RAM
Accumulator
B Register
Stack Pointer
Program Counter
Program Status Word
General Purpose
Register (Bank0-3)
Data Pointer Register
8KB
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