Maxim Integrated 71M6521BE Energy Meter IC Family Software User Manual

Page 39

71M652X Software User’s Guide

Revision 1.7

TERIDIAN Proprietary

39 of 138

Type definitions for internal data, 256 bytes, in the upper 128 bytes addressed indirectly:

typedef unsigned char idata

uint8i_t;

typedef unsigned short idata

uint16i_t;

typedef unsigned long idata

uint32i_t;

typedef signed char idata

int8i_t;

typedef signed short idata

int16i_t;

typedef signed long idata

int32i_t;

This is fairly fast, not battery-backed-up memory, slower than the data in the lower 128 bytes of internal memory.
Competes with data for space.

Type definitions for external data, 256 bytes of 2K of CMOS RAM:

typedef unsigned char pdata

uint8p_t;

typedef unsigned short pdata

uint16p_t;

typedef unsigned long pdata

uint32p_t;

typedef signed char pdata

int8p_t;

typedef signed short pdata

int16p_t;

typedef signed long pdata

int32p_t;

The upper byte of the XDATA address is supplied by the SFR 0xBF (ADRMSB) on the 71M6521 meter ICs. On other
8051 processors, P2 is used for this purpose. This memory range is accessed indirectly, still fairly fast, not battery
backed-up. This is a logical place for nonvolatile globals like power registers and configuration data.

Type definitions for external data, 2Kbytes of CMOS RAM, accessed indirectly via a 16-bit register:

This is the slowest but largest memory are, not battery backed-up. It can be used for everything possible. On Keil's
large model, this is the default.

typedef unsigned char xdata

uint8x_t;

typedef unsigned short xdata

uint16x_t;

typedef unsigned long xdata

uint32x_t;

typedef signed char xdata

int8x_t;

typedef signed short xdata

int16x_t;

typedef signed long xdata

int32x_t;

Type definitions for external read-only data, located in code space:

typedef unsigned char code

uint8r_t;

typedef unsigned short code

uint16r_t;

typedef unsigned long code

uint32r_t;

typedef signed char code

int8r_t;

typedef signed short code

int16r_t;

typedef signed long code

int32r_t;

Access is indirect via a 16-bit register. This is the slowest but largest space, nonvolatile programmable flash memory. It
should be used for constants and tables

This manual is related to the following products:

71M6521FE Energy Meter IC Family Software 71M6521DE Energy Meter IC Family Software