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10.1.3 A user guide to use shadow memory
(a) Set Bus Control Register [1:0] (EAh)= 01b (DMA mode).
(b) Configure the DMA source address to be the DMA destination address.
(c) Configure the DMA Transfer Count
(d) Register according to the transfer size you need.
(e) After DMA is transferred, set Bus Control Register [1:0] (EAh) to 2’b10 (Shadow mode).
(f) If the system is 8-bit boot mode, remember to switch to 16-bit mode after shadowing. Otherwise the
code fetching from SDRAM will still be 8-bit mode.

代碼片斷：
  unsigned cnt;
  unsigned seg;

asm cli

outport (BCR, 0x8001);
for (seg = 0xe; seg <= 0xf; seg++)
{
cnt = 0;
outport (DMA0SRCH, seg);
outport (DMA0SRCL, 0);
outport (DMA0DSTH, seg);
outport (DMA0DSTL, 0);
outport (DMA0TCNT, 0xffff);

outport (DMA0CR, START_DMA);

while (inport(DMA0TCNT))
if (cnt++ > 1000)
goto done;
}
outport (BCR, 0X8003);

outport (AUXCR, inport(AUXCR) | ~(0x80)); /* Enable 16-bit bus width */

asm sti
return 0;

    done:
asm sti
printf ("error: can not Shadow memory\n");

return -1;

為什么修改 bus width to 16 后，0xfff2 USIZE 位清不掉？？？

北京老陳	1樓
	RDC1610c shadow memory Post By：2005-9-16 16:49:00 [只看該作者] 10.1.3 A user guide to use shadow memory (a) Set Bus Control Register [1:0] (EAh)= 01b (DMA mode). (b) Configure the DMA source address to be the DMA destination address. (c) Configure the DMA Transfer Count (d) Register according to the transfer size you need. (e) After DMA is transferred, set Bus Control Register [1:0] (EAh) to 2’b10 (Shadow mode). (f) If the system is 8-bit boot mode, remember to switch to 16-bit mode after shadowing. Otherwise the code fetching from SDRAM will still be 8-bit mode. 代碼片斷： unsigned cnt; unsigned seg; asm cli outport (BCR, 0x8001); for (seg = 0xe; seg <= 0xf; seg++) { cnt = 0; outport (DMA0SRCH, seg); outport (DMA0SRCL, 0); outport (DMA0DSTH, seg); outport (DMA0DSTL, 0); outport (DMA0TCNT, 0xffff); outport (DMA0CR, START_DMA); while (inport(DMA0TCNT)) if (cnt++ > 1000) goto done; } outport (BCR, 0X8003); outport (AUXCR, inport(AUXCR) \| ~(0x80)); /* Enable 16-bit bus width */ asm sti return 0; done: asm sti printf ("error: can not Shadow memory\n"); return -1; 為什么修改 bus width to 16 后，0xfff2 USIZE 位清不掉？？？

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x10	2樓
	Post By：2005-9-16 20:31:00 [只看該作者] USIZE是read only位。

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北京	3樓
	Post By：2005-9-19 9:36:00 [只看該作者] (f) If the system is 8-bit boot mode, remember to switch to 16-bit mode after shadowing. Otherwise the code fetching from SDRAM will still be 8-bit mode. 如何處理？？

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x10	4樓
	Post By：2005-9-19 12:17:00 [只看該作者] 我們的ETR232i不需要這樣的shadow。你主要想實現什么功能？

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