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Re: 關於PIC18F8722外部介面的問題
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版主
 
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先看一下這份應用筆記: AN869
http://www.microchip.com/stellent/idc ... eId=1824&appnote=en012106
發表於: 2007/2/8 9:59
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關於PIC18F8722外部介面的問題
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新會員
 
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Dear All:
我的硬體架構是PIC18F8722 + CPLD 利用PIC18F8722的外部記憶體介面,去做memory map IO的動作,由CPLD去對外部記憶體介面解碼. 我用示波器測量外部記憶發現,AD0- AD7的波形與我預期的不同. 我定址0x20001 – 0x20005時, 示波器測量AD0後發現波型的變化並不是由 1-0-1-0-1-0而是 0-1-1-0-0, 我感覺是AD1的訊號出現在AD0上面了,整各訊號shift了.WHY?? 程式碼如下 rom far unsigned char volatile *dataptr; dataptr = (rom far unsigned char volatile*)0x20001; spi_tx[0]=*dataptr; dataptr++; spi_tx[1]=*dataptr; dataptr++; spi_tx[2]=*dataptr; dataptr++; spi_tx[3]=*dataptr; dataptr++; spi_tx[4]=*dataptr; 我用ICD2 debug 時候有確認dataptr的變化是由0x20001 – 0x20005 PIC18F8722的 config bit設定如下 Processor Mode : Ext Microcontroller Address Bus Width: 8 bit Bus Width:8 bit external bus
發表於: 2007/2/7 18:14
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