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Re: pic18F452使用8255扩展pin 的问题?
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資深會員
 
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對阿
我本來就沒什麼沒禮貌 不過看來你果然也是沒禮貌的 哈哈哈~
發表於: 2005/8/24 17:12
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Re: pic18F452使用8255扩展pin 的问题?
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新會員
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mr. nicecookie,
i think people who rude is you. 沒禮貌....?? If you do not know the answer please keep quiet. I had solved the problem, it do not work because of less one command. Thanks for every one who may help me to think. Sorry for typing english here because the PC I am using now do not have a chinese input software. Thank u.
發表於: 2005/8/23 19:51
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Re: pic18F452使用8255扩展pin 的问题?
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資深會員
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還大蝦勒
沒禮貌.... 不鳥你
發表於: 2005/8/19 9:52
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pic18F452使用8255扩展pin 的问题?
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新會員
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我的程序需要很多pin, 所以,用8255来扩展, 但是只有
input 没有output, 不懂是什么原因, 请大虾帮忙看看我的部分程序, 给我一些指点. bcf CS ;chip select = 0 ;;Reset 8255 ;;NOTE : Active high for 8255 Reset bsf RESET_8255 ;RESET = 1,clr the control register n all ports (A,B,C) call DELAYL bcf RESET_8255 ;power on ;reset the 8255 using the RESET pin ;set the write pin (WR) high ;put the control word on the data bus (selects the Mode) ;set A0 and A1 pins high ;set the write pin (WR) low for a very short duration, keeping A0 & A1 high ;set the write pin (WR) high again bsf _WR movlw 0x00 movwf TRISD movlw b'10000000' ;MODE:MODE SEL:PORTA:PORTC(UPPER):MODE SEL:PORTB:PORTC(LOWER) movwf PORTD ;data from portD of PIC nop bsf A0 ;Control Word -> data bus , A0 =1 bsf A1 ;Control Word -> data bus , A1 =1 bcf _WR nop nop bsf _WR ;output movlw 0x00 movwf TRISD movlw 0xff movwf PORTD ;OUTPUT OPERATION to 8255, portA (WRITE) ;Data bus --> portA bcf A1 ; A1 A0 _RD _WR bcf A0 ; 0 0 1 0 nop bsf _RD bcf _WR NOP nop bsf _WR 在线等待,,,,,~~~~~~~ 谢谢
發表於: 2005/8/18 17:06
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