PIN versus CON Declarations
playinmyblues_nscc
Posts: 38
Hi. I am working my way through the StampWorks book and have come across a small issue regarding the naming pins. In programs for experiments 11, 12, and 13 (and maybe others) there are declarations in the
I/O Definitions section. Here is an example from experiment 12 (framed by asterisks):
********************************************************
' -- I/O Definitions --
E PIN 1 ' Enable pin
RW PIN 2 ' Read/Write
RS CON 3 ' Register Select
LcdBus VAR OUTB ' 4-bit data bus
********************************************************
The whole program is inside a zip file downloaded under the "Downloads and Resources" section here: http://www.parallax.com/Store/Microcontrollers/BASICStampProgrammingKits/tabid/136/CategoryID/11/List/0/SortField/0/Level/a/ProductID/329/Default.aspx
When this program is run directly from the source code, it runs as it should. When the line dealing with I/O Pin 3 is named as a "PIN" instead of a "CON" as shown above, the program runs the same.
My question is why are I/O Pins 1 and 2 named as PINs whereas I/O Pin 3 is named a CON? Is it to demonstrate that either declaration will work or is there something that I have missed or not come across yet?
Just for reference, page 20 in the StampWorks book under the section called "4. Naming I/O Pins" provides information about the declaration and naming of I/O pins but nothing about naming the pins with the CON declaration. I also reviewed pages 99 - 102 in the Basic Stamp Syntax and Reference Manual about the use of the PIN declaration but did not find out why the difference above might occur.
I/O Definitions section. Here is an example from experiment 12 (framed by asterisks):
********************************************************
' -- I/O Definitions --
E PIN 1 ' Enable pin
RW PIN 2 ' Read/Write
RS CON 3 ' Register Select
LcdBus VAR OUTB ' 4-bit data bus
********************************************************
The whole program is inside a zip file downloaded under the "Downloads and Resources" section here: http://www.parallax.com/Store/Microcontrollers/BASICStampProgrammingKits/tabid/136/CategoryID/11/List/0/SortField/0/Level/a/ProductID/329/Default.aspx
When this program is run directly from the source code, it runs as it should. When the line dealing with I/O Pin 3 is named as a "PIN" instead of a "CON" as shown above, the program runs the same.
My question is why are I/O Pins 1 and 2 named as PINs whereas I/O Pin 3 is named a CON? Is it to demonstrate that either declaration will work or is there something that I have missed or not come across yet?
Just for reference, page 20 in the StampWorks book under the section called "4. Naming I/O Pins" provides information about the declaration and naming of I/O pins but nothing about naming the pins with the CON declaration. I also reviewed pages 99 - 102 in the Basic Stamp Syntax and Reference Manual about the use of the PIN declaration but did not find out why the difference above might occur.
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