UPSD3312D-40U6 datasheet(21/231 Pages) STMICROELECTRONICS

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uPSD33xx

MCU MODULE DISCRIPTION

This section provides a detail description of the

MCU Module system functions and peripherals, in-

cluding:

■

8032 MCU Registers

■

Special Function Registers

■

8032 Addressing Modes

■

uPSD33xx Instruction Set Summary

■

Dual Data Pointers

■

Debug Unit

■

Interrupt System

■

MCU Clock Generation

■

Power Saving Modes

■

Oscillator and External Components

■

I/O Ports

■

MCU Bus Interface

■

Supervisory Functions

■

Standard 8032 Timer/Counters

■

Serial UART Interfaces

■

IrDA Interface

■

I2C Interface

■

SPI Interface

■

Analog to Digital Converter

■

Programmable Counter Array (PCA)

Note: A full description of the 8032 instruction set

may be found in the uPSD33xx Programmers

Guide.

8032 MCU REGISTERS

The uPSD33xx has the following 8032 MCU core

registers, also shown in Figure 11.

Figure 11. 8032 MCU Registers

Stack Pointer (SP)

The SP is an 8-bit register which holds the current

location of the top of the stack. It is incremented

before a value is pushed onto the stack, and dec-

remented after a value is popped off the stack. The

SP is initialized to 07h after reset. This causes the

stack to begin at location 08h (top of stack). To

avoid overlapping conflicts, the user must initialize

the top of the stack to 20h if all four banks of reg-

isters R0 - R7 are used, and the user must initialize

the top of stack to 30h if all of the 8032 bit memory

locations are used.

Data Pointer (DPTR)

DPTR is a 16-bit register consisting of two 8-bit

registers, DPL and DPH. The DPTR Register is

used as a base register to create an address for in-

direct jumps, table look-up operations, and for ex-

ternal data transfers (XDATA). When not used for

addressing, the DPTR Register can be used as a

general purpose 16-bit data register.

Very frequently, the DPTR Register is used to ac-

cess XDATA using the External Direct addressing

mode. The uPSD33xx has a special set of SFR

registers (DPTC, DPTM) to control a secondary

DPTR Register to speed memory-to-memory

XDATA transfers. Having dual DPTR Registers al-

lows rapid switching between source and destina-

tion addresses (see details in DUAL DATA

POINTERS, page 37).

Program Counter (PC)

The PC is a 16-bit register consisting of two 8-bit

registers, PCL and PCH. This counter indicates

the address of the next instruction in program

memory to be fetched and executed. A reset forc-

es the PC to location 0000h, which is where the re-

set jump vector is stored.

Accumulator (ACC)

This is an 8-bit general purpose register which

holds a source operand and receives the result of

arithmetic operations. The ACC Register can also

be the source or destination of logic and data

movement operations. For MUL and DIV instruc-

tions, ACC is combined with the B Register to hold

16-bit operands. The ACC is referred to as “A” in

the MCU instruction set.

B Register (B)

The B Register is a general purpose 8-bit register

for temporary data storage and also used as a 16-

bit register when concatenated with the ACC Reg-

ister for use with MUL and DIV instructions.

AI06636

Accumulator

B Register

Stack Pointer

Program Counter

Program Status Word

General Purpose

Data Pointer Register

PCH

DPTR(DPH)

PCL

PSW

R0-R7

DPTR(DPL)

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