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Forum Index : Microcontroller and PC projects : Port Function

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viscomjim
Guru

Joined: 08/01/2014
Location: United States
Posts: 925

Posted: 08:28am 10 Jun 2015

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Working on a project where I need to read 4 I/O lines at one time and write 4 I/O lines at one time. So for the write I see I can use the port command something like this...

port(2,4) = &HF

But for the function to read a 4 bit port does one do this...

A = port(2,4)

or

A = &H(port(2,4))

assigning the 4 bits of the port to a variable?

Thanks!!!!!

Chris Roper
Senior Member

Joined: 19/05/2015
Location: South Africa
Posts: 280

Posted: 08:51am 10 Jun 2015

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viscomjim said But for the function to read a 4 bit port does one do this...

A = port(2,4)

or

A = &H(port(2,4))

The first option, if you then want it displayed:

PRINT HEX$(A)

or

PRINT BIN$(A, 4)

To separate the bits you could use:

bit0 = A AND 1
bit1 = (A >> 1) AND 1
bit2 = (A >> 2) AND 1
bit3 = (A >> 3) AND 1

Cheers
Chris

Edited by Chris Roper 2015-06-11

http://caroper.blogspot.com/

viscomjim
Guru

Joined: 08/01/2014
Location: United States
Posts: 925

Posted: 10:49am 10 Jun 2015

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Thanks Chris, I will give this a whirl.

Chris Roper
Senior Member

Joined: 19/05/2015
Location: South Africa
Posts: 280

Posted: 11:47am 10 Jun 2015

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If you run this code you can watch the BIT's as you play with the input signals:

[code]
SetPin 2,din
SetPin 3,din
SetPin 4,din
SetPin 5,din

Do
Print Chr$(27)+"[2;2H"; ' locate Cursor row 2 col 2

a = Port(2,4)
Print Bin$(a,4);

Pause 100 ' prevent flashing on cursor relocate
Loop
[/code]

http://caroper.blogspot.com/

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