IF B0 < 0 !?!?! in PIC Basic

[arvinfx]

hi

I need to compare a NEGATIVE variant value with 0 in (Pic Basic pro Studio).

look at the code

if  B0 < 0 then  
lcdout $fe,1,"-" 
else 
lcdout $fe,1,"+" 
endif

and if i set B0 = -30 or any negative value the output on LCD is +

what happened to Pic Basic pro!

 

[arvinfx]

help plz

 

[bassnut]

I dont know about Pic basic pro, but most simple basic languages dont allow negative values, only positive integers, so somewhere set your "0" to say 127 (half of 255, by adding 127 to the original value) and then use your code the way it is but with "if B0 < 127", so 127 becomes the "default" zero thoughout your program.

 

[arvinfx]

I dont know about Pic basic pro, but most simple basic languages dont allow negative values, only positive integers, so somewhere set your "0" to say 127 (half of 255, by adding 127 to the original value) and then use your code the way it is but with "if B0 < 127", so 127 becomes the "default" zero thoughout your program.

Thanks but this way is very bulk of code and process!

Is any way in assembly language?

 

[ericgibbs]

Thanks but this way is very bulk of code and process!

Is any way in assembly language?

hi,
How have you defined B0, as byte/word ....?

The Basic only uses unsigned BYTE/WORD Integers, but signed DWORD

 

[arvinfx]

hi,
How have you defined B0, as byte/word ....?

The Basic only uses unsigned BYTE/WORD Integers, but signed DWORD

I use Word!

B0 var word

 

[Nigel Goodwin]

I use Word!

B0 var word

So positive numbers only.

 

[ericgibbs]

I use Word!

B0 var word

As a simple test DIM B0 as DWORD.

Perhaps there is an easier way to solve the problem... whats the 'source' of the B0 variable, how is it derived.?

 

[arvinfx]

As a simple test DIM B0 as DWORD.

Perhaps there is an easier way to solve the problem... whats the 'source' of the B0 variable, how is it derived.?

B0 is a output value of DS1820 (1-Wire thermometer )

I use PICBasic Pro v2.45 and your sample code is for Visal Basic!

 

[ericgibbs]

B0 is a output value of DS1820 (1-Wire thermometer )

I use PICBasic Pro v2.45 and your sample code is for Visal Basic!

I know you use PICBasic, I downloaded the instruction manual so that I could answer your question, which if you read the VAR definitions it clearly tells you which are signed and unsigned variables.

As the attached image is from the PICBasic Pro manual how do you come to the conclusion its for Visual Basic.

Have you tried DIM B0 as DWORD.?

 

[ericgibbs]

B0 is a output value of DS1820 (1-Wire thermometer )

As I understand the DS1820, its a WORD output format.?

Have you considered using the Th and TL in the users Alarm registers, bit7 the Sign(S) bit defines neg/pos values.

Also if you are trying to measure down to -55Cdeg, why not just add 55 to the read value and do an unsigned test for negative temperatures.?

 

[arvinfx]

As I understand the DS1820, its a WORD output format.?

Have you considered using the Th and TL in the users Alarm registers, bit7 the Sign(S) bit defines neg/pos values.

Also if you are trying to measure down to -55Cdeg, why not just add 55 to the read value and do an unsigned test for negative temperatures.?

I think its end way to do my compare !

Ok

I test bit of Signe and if it is present my code is:

if b0 >65000 then ; is negative value!?
If b0 < 65531 then  ; Is b0 < -3 
lcdout $c0,1,"-" 
end if 
endif

its correct!?

 

[bassnut]

No, you still cant do "is b0 < -3" if the b0 variable is a word ;-).

 

[ericgibbs]

hi,
Look at this image.

If the upper byte of the tempr value is greater than 0x00 then the tempr is negative.

OK.?

 

[arvinfx]

No, you still cant do "is b0 < -3" if the b0 variable is a word ;-).

you say i use Dword?! PICBASIC haven`t this variable men!

 

[arvinfx]

OK , thanks a lot
I now what to do now

 

[ericgibbs]

you say i use Dword?! PICBASIC haven`t this variable men!

I have downloaded the manual from this site.!

PICBASIC Programming &mdash; Evolved | Proton Development Suite

Thats where I got the DWORD from..

 

[arvinfx]

I have downloaded the manual from this site.!

PICBASIC Programming &mdash; Evolved | Proton Development Suite

Thats where I got the DWORD from..

Look at this :

https://i44.tinypic.com/68dcmf.jpg

 

[Nigel Goodwin]

You've never explained (and still haven't) exactly what compiler you're using - but it seems pretty likely that it doesn't do negative numbers.

 

[arvinfx]

You've never explained (and still haven't) exactly what compiler you're using - but it seems pretty likely that it doesn't do negative numbers.

Please look at 9th post at first page.