STC12LE5616AD datasheet(61/377 Pages) STC

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512 Bytes

expanded RAM

01FFH

0000H

Auxiliary RAM

3.2.2 Auxiliary RAM

There are 512 bytes of additional data RAM available on STC12C5620AD. They may be accessed by the

instructions MOVX @Ri or MOVX @DPTR. The auxiliary RAM is the default target for the address range from

0x0000 to 0x01FF and can be indirectly accessed by move external instruction, “MOVX @Ri” and “MOVX @

DPTR”.

For KEIL-C51 compiler, to assign the variables to be located at Auxiliary RAM, the “pdata” or “xdata” definition

should be used. After being compiled, the variables declared by “pdata” and “xdata” will become the memories

accessed by “MOVX @Ri” and “MOVX @DPTR”, respectively. Thus the STC12C5620AD hardware can access

them correctly.

An example program for internal expanded RAM demo of STC12C5620AD :

;/*--------------------------------------------------------------------------------*/

;/* --- STC MCU International Limited -----------------------------------*/

;/* --- STC 1T Series MCU internal expanded RAM Demo -----------*/

;/* If you want to use the program or the program referenced in the */

;/* article, please specify in which data and procedures from STC */

;/*-------------------------------------------------------------------------------*/

#include <reg52.h>

#include <intrins.h>

/* use _nop_() function */

sfr AUXR = 0x8e;

sfr IPH = 0xb7;

sfr WDT_CONTR = 0xe1;

sfr ISP_DATA

= 0xe2;

sfr ISP_ADDRH

= 0xe3;

sfr ISP_ADDRL

= 0xe4;

sfr ISP_CMD

= 0xe5;

sfr ISP_TRIG

= 0xe6;

sfr ISP_CONTR

= 0xe7;

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