JohnieWalker
Newbie level 1
Hi guys,
I've read all kind of stuff on internet and this forum but one thing still confuses me.
I have a study project.
A module is connected to 8051 Port 3.
On P3.0-P3.3 this module connects switches, on P3.4-P3.7 this module connects LED's.
When switch is pressed it triggers a logical "1" to be present on the line associated with this switch.
To light a LED you need to send a logical "1" to the line associated with this LED.
The homework is:
When switch 1 (on P3.0) is pressed light up LED's 1 2 3 4 in sequence, when switch 4 is pressed light them up in 4 3 2 1 sequence.
Ports 3.0 and 3.3 which are in question are setup for input by MOV P3,#00001001b.
The big question is: should I read input pins as low or as high? So when switch "1" is pressed and it produces logical "1" on the line associated with it (P3.0), what will I read?
As I understand a logical way would be to do like that:
but it doesn't work for me, since P3.0 returns as 1 even after initial setup.
So, should I expect "0" on P3.0 (and use JC instead) when switch 1 line is "1" or I'm misunderstanding something?
Like that
Thank you.
I've read all kind of stuff on internet and this forum but one thing still confuses me.
I have a study project.
A module is connected to 8051 Port 3.
On P3.0-P3.3 this module connects switches, on P3.4-P3.7 this module connects LED's.
When switch is pressed it triggers a logical "1" to be present on the line associated with this switch.
To light a LED you need to send a logical "1" to the line associated with this LED.
The homework is:
When switch 1 (on P3.0) is pressed light up LED's 1 2 3 4 in sequence, when switch 4 is pressed light them up in 4 3 2 1 sequence.
Ports 3.0 and 3.3 which are in question are setup for input by MOV P3,#00001001b.
The big question is: should I read input pins as low or as high? So when switch "1" is pressed and it produces logical "1" on the line associated with it (P3.0), what will I read?
As I understand a logical way would be to do like that:
Code ASM - [expand]
but it doesn't work for me, since P3.0 returns as 1 even after initial setup.
So, should I expect "0" on P3.0 (and use JC instead) when switch 1 line is "1" or I'm misunderstanding something?
Like that
Code ASM - [expand]
Thank you.
Last edited: