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lcd tutorial


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Nibs

Fri Jun 12 2009, 07:57AM

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help needed newbie question
following lcd tutorial but don't know where info comes from
code asm
lcd_ data equ P2
lcd_d7 equ P2.7
lcd_rs equ P1.0

after the equ where is it refering to how do i get that info
what does P2,P2.7,P1.0,P1.1,P1.2 mean

gopi

Fri Jun 12 2009, 11:49AM

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It says that lcd_data is equal to P2. i.e., it is very similar as if like within 'C' language " #define pi 3.14".

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ExperimenterUK

Fri Jun 12 2009, 01:06PM

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Nibs wrote ...

after the equ where is it refering to how do i get that info
what does P2,P2.7,P1.0,P1.1,P1.2 mean

In this case P2 stands for Port 2.
P2.7 means pin 7 of port 2.

The assembler programs already "knows" that P2 means port 2 because some simple
definitions are built in.
Many similar definitions are built into assemblers, you should be able to find them listed in
header files supplied with your program.

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Ajay Bhargav

Fri Jun 12 2009, 02:59PM

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Nibs, which part of tutorial you feel hard to understand, Do tell me i will improve it.

I think if i add a circuit in that place that will help is it? do give me your feedback.

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Nibs

Sat Jun 13 2009, 09:55PM

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newbie i had problem understanding the first bit of asm code didn't realise it was defining it to mcu port and portbit the part after equ p2.7 or equ P1.0,P1.2 haden't seen anything defined like that ,only seen lcd_rs equ portD,1 the tutorial helped me so much still a long way to go playing with cursor movement would like to get to display both lines and just stop not loop:bye
LCD_data equ P2 ;LCD Data port
LCD_D7 equ P2.7 ;LCD D7/Busy Flag
LCD_rs equ P1.0 ;LCD Register Select
LCD_rw equ P1.1 ;LCD Read/Write
LCD_en equ P1.2 ;LCD Enable