IF THEN Help

Bassist

I need to send "sre*" to a 232 device. I am able to do that but I need to send the string when pin0 = 1. I have not been able to figure out the IF THEN· statement. Any help will be appreciated. Thanks in advance.

Franklin

Show us your code!

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- Stephen

Bassist

Here you go.· If there is a better way to do this please let me know.

Record:
· IF (IN0 = 1) THEN Main




·Main:
·· DO
· SEROUT 16, 16780, [noparse][[/noparse]"sre*",CR]

· PAUSE 2500
· LOOP


· END

Franklin

So, does that code work for you? If not you need to think about what the commands do and why it is not working. (HINT) What happens if IN0 is not 1

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- Stephen

erco

No parens.

IF IN0=1 THEN Main

unless you are using a BS1, in which case

IF PIN0=1 THEN Main

The PBasic editor turns colors to help ID syntax/typing errors. Make sure you used "zero" and not "oh".

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·"If you build it, they will come."

Bassist

I took the parens out and it still works the same. When I look at it with Hyperterminal it displays sre* after 2.5 seconds whether the If statement is in or not....

erco

You do have an external connection to pin0 that goes from zero volts to +5v volts? Guaranteed? Make direct connections and retry.

Attach your entire program.

And per Stephen, you must have something like:

Record:
IF (IN0 = 1) THEN Main
goto record' loop back if IN0=0

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·"If you build it, they will come."

Bassist

Thanks Erco, that did the trick. Today is my first day so I have alot to learn. I have another question. I think I read that if you are using the programming·port to send data out·that you need both the transmit and receive wires connected to get the proper voltage levels. The application I hope to use this for requires the receive wire be connected to another device, so I will only have the transmit wire available. Will·this work? Do I need to use a MAXIM 232 and a output pin?· Thanks again to both of you, I appreciate the help!



' TEST.bs2
' This program transmits the string "sre*" followed by a
' carriage-return at 2400 baud, inverted, N81 format.

' {$STAMP BS2}
' {$PBASIC 2.5}
·INPUT 0

·Record:
· IF IN0 = 1 THEN Main
· GOTO Record

·Main:
· DO
· SEROUT 16, 16780, [noparse][[/noparse]"sre*",CR]
· PAUSE 2500
· LOOP

· END

Bassist

I was mixed up on the receive and transmit wires on the last post. I will only have the receive wire available, not the transmit. TNX

Bassist

I found out I need CR/LF for this to work. I do not see LF referenced anywhere... HELP

Bassist

Okay so I'm stupid...

Bassist

when I add LF here:

Main:
DO
SEROUT 16, 16780, [noparse][[/noparse]"sre*",CR,LF]
PAUSE 2500
LOOP

END

It spits out the string repeatedly no matter the state of input 0. I think I need to send the hex representation of sre*CRLF as the string. How do I do this? Thanks, Tab

Franklin

Why would you think it would act otherwise, Look at your code:

start loop
serout
wait a while
repeat loop
there is no checking of anything in the loop

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- Stephen

Bassist

I removed the DO and LOOP. It works better but is still not doing what I want.

Spiral_72

Computers do EXACTLY what you tell them, nothing more, nothing less. It's a different way of thinking, kind of like telling a child what to do.


An If-Then statement works like this:

If IN0 = 1 then do something........if not, then go to the next instruction.

So, if you have:

IF IN0 = 1 then goto main

Main:
send some serial data

END



It will execute the Main routine regardless of pin 0's state because if IN0 = 1, it goes to the routine Main. If IN0 = 0 it falls through the condition (because it's not true) and executes the next command, which happens to be THE MAIN ROUTINE!!!

By doing the

Record:
IF IN0=1 goto Main
goto Record

You'll check pin 0 over and over forever..... or until pin 0 = 1...... the little "GOTO Record" is the next instruction past the If-Then condition, so when the If-Then is false, it executes the next command which starts the check again. When pin 0 = 1, it leaves the little check routine and executes new code (your Main routine)


The END statement stops everything. Period. It don't do no mo' until you power off or hit the reset button..... So depending on what you want you code to do, you might want to put a "Goto Record" after your Main routine, but before the END command.... so if pin 0 = 1, it sends your serial data, then starts the whole program again.


I hope all that makes sense and is helpful..... Now I go back to work [noparse]:)[/noparse]

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"puff"...... Smile, there went another one.

Bassist

Thanks Spiral_72. That helps!