Can defines be changed with port input?

[Archangel]

Hello Again Everyone,
Is it possible to alter <h4>DEFINES</h4> by assigning an alias or variable to their value and then making them subject to port input?
I want to alter the DEFINE HSER_SPBRG and LCD lines = X defines by switching port inputs, but I get assembler errors if I try method listed below.
Thank You for your patience, and help.
Joe



DEFINE HSER_SPBRG BAUD ' FOR 20MHZ 129 = 2400, 32=9600,25 @ 4 for 2400
define BAUD Var
BAUD = 129
if PortB.3 =1 then
BAUD = 32

[Acetronics2]

Hi, Joe

As DEFINEs write to special registers or PBP constants ... you could consider it's "a kind" of CON statement !!!

for values, a look to PBPxx.lib and the function listing could give you the value name ... in order you to change it.

For registers, It wil be much better to change their values Through assembler ( As DEFINEs do ...) : Addressing them directly ...

But Think to disable the concerned peripheral before any change ... or the mix might be funny ...

Alain

[Charles Linquis]

You don't need to change defines to change the baud rate. In PBP, the baud rate generator gets set once, at the beginning of the program. Your program can change it any time later by writing to the SPBRG register. I switch between baud rates all the time in my programs.

Just remember - when using the UART, your program writes the output buffer and moves on, which means that you can still be outputting a byte many instructions after the HSEROUT. You should wait at least two byte-times after any HSEROUT command before you change the baud rate.

[Archangel]

You don't need to change defines to change the baud rate. In PBP, the baud rate generator gets set once, at the beginning of the program. Your program can change it any time later by writing to the SPBRG register. I switch between baud rates all the time in my programs.

Just remember - when using the UART, your program writes the output buffer and moves on, which means that you can still be outputting a byte many instructions after the HSEROUT. You should wait at least two byte-times after any HSEROUT command before you change the baud rate.

Hi Charles,
Happy Thanksgiving to you and all who share this forum!
I am thankful to all who post here.

So are you saying, the statement posted below:
<h4>DEFINE HSER_SPBRG 32 ' __ _ FOR 20MHZ 129 = 2400, 32=9600,25 @ 4 for 2400, </h4> might be written as something like:<h4> IF PortB.n = 1
THEN HSER_SPBRG = 32
ELSE
HSER_SPBRG = 129</h4>
JS

EDIT
AHHHH SOOO
I see, just define it to your default and change it later with SPBRG = "new setting number"
<h3>THANKS CHARLES !</h3>

[mister_e]

SPBRG is the USART register. so just writing to it change the baudrate.

SPBRG=x
SPBRG=y
'
'
'
and so on

AND you could also skip all DEFINEs, just write to the according register... as the PICMultiCalc .

RCSTA = $90 ' Enable serial port & continuous receive
TXSTA = $24 ' Enable transmit, BRGH = 1
SPBRG = 129 ' 9600 Baud @ 0.16%

[Archangel]

AND you could also skip all DEFINEs, just write to the according register... as the PICMultiCalc .

Thank You mister_e,
so many subtel little turns and twists to learn. Can you answer this?
If I define

DEFINE LCD_LINES 2

and send

serout PortB.4,T9600,[254,128,"9600 baud line 1~"] '128 so as not to add space
pause 100
serout PortB.4,T9600,[254,192,"9600 baud line 2~"] 
pause 100
serout PortB.4,T9600,[254,148,"9600 baud line 3~"] 
pause 100
serout PortB.4,T9600,[254,212,"9600 baud line 4~"]
pause 100

It still displays all 4 lines as if define was set to 4?
JS