MAC7200 datasheet(537/976 Pages) FREESCALE

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SSM Bus Aborts

MAC7200 Microcontroller Family Reference Manual, Rev. 2

Freescale Semiconductor

459

Because the DMA is executing independently of the processor core, using the STATUS register in software

is discouraged, as the latency for the execution of the above code may be longer than the DMA is actually

active. Use of this register is intended for debug purposes only.

25.5.4

Using the MEMCONFIG register

Bit 15 of the MEMCONFIG register is reserved for future use; therefore you should mask this bit out when

reading this register, as shown in the following code example:

In File registers.h:

#define SSM_BASE_ADDRESS

0xFC008000/* Example only ! */

/* Following example assumes short is 16-bits */

volatile unsigned short *MEMCONFIG = (volatile unsigned short *)

(SSM_BASE_ADDRESS+0x0004);

In File main.c:

#include "registers.h"

unsigned short memconfig;

unsigned char sram_valid;

unsigned char sram_size;

unsigned char iflash_valid;

unsigned char iflash_size;

unsigned char dflash_valid;

unsigned char dflash_size;

memconfig = *MEMCONFIG & 0x7fff;

sram_valid = (unsigned char) (memconfig & 0400) >> 10;

iflash_valid = (unsigned char) (memconfig & 0020) >> 5;

dflash_valid = (unsigned char) (memconfig & 0001);

sram_size = (unsigned char) (memconfig & 7800) >> 11;

iflash_size = (unsigned char) (memconfig & 02C0) >> 6;

dflash_size = (unsigned char) (memconfig & 001e) >> 1;

25.6

SSM Bus Aborts

The SSM module supports Peripheral Bus bus aborts, and enforces the following memory map:

Supervisor Access: Unused.

25.7

SSM Differences from MAC71xx

•

Added PER_ABORT field to the ERROR register

•

Added Nexus information to STATUS register

•

Changed SRAMSIZE field from 4 bits to 5 bits and re-encoded

Table 25-13. SSM Bus Aborts

Abort

Allowed

$0000-$000f

$0010-$3fff

MAC7200 Datasheet(PDF) 537 Page - Freescale Semiconductor, Inc

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