| Author |
Message |
vanbayhoang
Joined: 31 Oct 2009
Posts: 5
Location: HVB
|
 31 Oct 2009 14:55 help me communicate with 8255! |
|
|
|
|
Please can any one provide me asemble code for communicate with 8255 using at89c51!
thanks!
|
|
| Back to top |
|
 |
IanP
Joined: 05 Oct 2004
Posts: 6490
Helped: 1542
Location: West Coast
|
|
| Back to top |
|
|
Google
AdSense
|
01 Nov 2009 2:21 Ads |
|
|
|
|
|
|
| Back to top |
|
|
vanbayhoang
Joined: 31 Oct 2009
Posts: 5
Location: HVB
|
01 Nov 2009 3:08 help me communicate with 8255! |
|
|
|
|
thanks!
you have asembly code? I need code asembly!
sorry!, My english is not good.
|
|
| Back to top |
|
|
IanP
Joined: 05 Oct 2004
Posts: 6490
Helped: 1542
Location: West Coast
|
01 Nov 2009 3:25 Re: help me communicate with 8255! |
|
|
|
|
First, map 8255 as an external memory - that's the easiest way ..
See attached picture ..
On power on all mode/direction bits in the Control Register are set to "0" and that means that all 3 ports are set to be outputs ..
To send data to, say, port A, use the following command:
| Code: |
MOV DPTR, #addres of A; in this example it is #4000h
MOV A, #what you want to send
MOVX @DPTR, A |
Other addresses are as follows:
Address 4000H: port A
Address 4001H: port B
Address 4002H: port C
Address 4003H: configuration register
To set Port A as inputs, you have to set D4 in the Control Register.
| Code: |
MOV DPTR, #4003h
MOV A, #00010000b
MOVX @DPTR, A |
and then:
| Code: |
MOV DPTR, #4000h; addres of Port A
MOV A, @DPTR |
will read PORT A of the 8255 ..
Rgds,
IanP
|
|
| Back to top |
|
|
vanbayhoang
Joined: 31 Oct 2009
Posts: 5
Location: HVB
|
01 Nov 2009 4:08 help me communicate with 8255! |
|
|
|
|
thanks for your help!
have fun!
|
|
| Back to top |
|
|
