Energy Meter IC Family Software Instruction Manual

71M652X Software User’s Guide

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5 DEMO CODE DESCRIPTION

5.1 80515 DATA TYPES AND COMPILER-SPECIFIC INFORMATION

5.1.1 Data Types

The 80515 MPU core is an 8-bit micro controller (MPU); thus operations that use 8-bit data types such as “char” or

“unsigned char” work more efficiently than operations that use multi-byte types, such as “int” or “long”. The Keil C51

compiler supports ANSI C data types as well as data types that are unique to the generic 8051 controller family. Table

5-2 lists available data ty

pes. Please refer to the Keil Cx51 Compiler User’s Guide for more details.

Various types of address spaces are available for the 80515 MPU core of the 71M652X, and in order to utilize the

various memory space types efficiently, the Demo Code uses variable type definitions (typedefs.) presented in this

chapter.

To understand the data types, it helps to examine the internal data memory map of the 80515 MPU core, as shown in

Table 5-1: .

Address Direct addressing Indirect addressing

0xFF

Special Function Registers

(SFRs)

RAM

0x80

0x7F

Byte-addressable area

0x30

0x2F

Bit-addressable area

0x20

0x1F

0x00

Table 5-1: Internal Data Memory Map