Word array behaving like byte array.... wierd

[forgie]

Hi there,
I have a piece of code which looks like thus:
<code>
Sample_Buffer[Sample_Index] = ADC_Buffer
</code>


All of these variables are declared as variables. When I check the data, Sample_Buffer[Sample_Index] is always less then 256, although I know that the data in ADC_Buffer is often higher then this.

I have tested it by changing the code to this:

<code>
if ADC_Buffer > 255 then
lcdout cmd, cls, "BIG NUM"
endif
sample_buffer[sample_index] = adc_buffer
</code>

And sure, enough, "BIG NUM" is spat out on the LCD. If I use the same check for the Array Variable after copying the data into the array, it always comes back as being < 256.

Where is the other half of my word going??? Has anyone else seen similar behaviour? Am I doing something really stupid?

EDIT: This is on an 18f452, using PBP 2.43

[Melanie]

We assume that...

ADC_Buffer has been defined as a WORD variable

and that...

Sample_Buffer has been defined correctly as a WORD ARRAY

[forgie]

<code>
Sample_Buffer var word[n_samples] 'Array to store samples in
Sample_Index var word
ADC_Buffer var word 'Return value for ADC_Reading
</code>

This is copied straight from my sourcecode....

[NavMicroSystems]

This is copied straight from my sourcecode....

	Sample_Buffer	var word[n_samples]

Are you really using a variable (n_samples) to specify the size of the array?

[forgie]

Lol I don't think PBP would compile if it were a VAR... nope, it's a constant and it's equal to 300.

[Bruce]

See if this works. If not, it might be due to your older version of PBP. I know
they've made a few changes/fixes for the 18F series since v2.43.

Tested with PIC18F452 PBP v2.46:

' Lab-X1 LCD definitions
Define  LCD_DREG        PORTD
Define  LCD_DBIT        4
Define  LCD_RSREG       PORTE
Define  LCD_RSBIT       0
Define  LCD_EREG        PORTE
Define  LCD_EBIT        1
Define  LCD_COMMANDUS   2000
Define  LCD_DATAUS      50

n_samples CON 300
Sample_Buffer var word[n_samples] 'Array to store samples in
Sample_Index var word
ADC_Buffer var word 'Return value for ADC_Reading

CLEAR
ADCON1 = 7      ' Set PORTA and PORTE to digital
ADC_Buffer = 1200
PAUSE 1000
lcdout $fe,1     ' Cls  Clear LCD screen

Main:
     FOR Sample_Index = 0 to 299
       Sample_Buffer[Sample_Index] = ADC_Buffer
       ADC_Buffer = ADC_Buffer + 100
       LCDOUT "Sample: ",DEC Sample_Index," = ",DEC Sample_Buffer[Sample_Index]
       PAUSE 2000
       LCDOUT $fe,1     ' Cls  Clear LCD screen
    NEXT Sample_Index
    GOTO Main
    
    end

[NavMicroSystems]

Lol I don't think PBP would compile if it were a VAR... nope, it's a constant and it's equal to 300.

you said:

This is copied straight from my sourcecode....

and there was no

n_samples CON 300

ROFL