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LAT v PORT

 
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Storic



Joined: 03 Dec 2005
Posts: 182
Location: Australia SA

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LAT v PORT
PostPosted: Mon Dec 11, 2006 6:37 am     Reply with quote
A question on LAT and PORT. in this link http://www.ccsinfo.com/forum/viewtopic.php?t=29126
I made ref to the PORT BIT,
Code:
#byte State_L = 0xF81 // PORT B; PORT A = 0xF80
#bit Status_LED = State_L.2

the example reference LAT BIT.
Code:

#byte    Port_B = 0xF8A
#bit     Status_LED = Port_B.5

I used the PORT BIT when testing weather the PORT BIT is High or Low,
Can I assume that LAT BIT controls the BIT high or low.

ANdrew
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rwyoung



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PostPosted: Mon Dec 11, 2006 8:25 am     Reply with quote
Read the PORT bit, write the LATch bit.
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Storic



Joined: 03 Dec 2005
Posts: 182
Location: Australia SA

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PostPosted: Mon Dec 11, 2006 3:13 pm     Reply with quote
Smile Thanks
I found this after my post, your help is clearer than the extracted quote below

Confused (as extracted from the microchip pdf file "39564c.pdf")
Quote:

Each port has three registers for its operation. These
registers are:
• TRIS register (data direction register)
• PORT register (reads the levels on the pins of the
device)
• LAT register (output latch)
The data latch (LAT register) is useful for read-modify-
write operations on the value that the I/O pins are
driving.

The Data Latch register (LATB) is also memory
mapped. Read-modify-write operations on the LATB
register reads and writes the latched output value for
PORTB.

extracted from "9.0 I/O PORTS"

ANdrew
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