AVR-Chat

David VanHorn Wrote
>Is there a reason that I can't use a char as a pointer in an array of ints?
<snip>
>Started with this code:

Change ADC_Pointer declaration to

unsigned char ADC_Pointer;

Also I'd call it ADC_Index so no one thinks it is actually a pointer
>// Reads all 8 channels even though we only use two.
>ISR(ADC_vect)
>{	// Store in array of locations per channel flag
>	
>	// Read the channel data MUST BE IN LOW-HIGH order!
>	// low byte of ADC_Reading = ADCL
>	// high byte of ADC_Reading = ADCH
>	ADC_Data[ADC_Pointer] = ADCW;          // ADC_Reading;
>
>	// Select the next channel
>	ADC_Pointer++;  						//Only I ever increment this!
>	if (ADC_Pointer > 7) ADC_Pointer=0;

Change above two lines to (1)

        ADC_Pointer = (ADC_Pointer+1)&7u; /* Use only 3 low oder bits as an
index */

If GCC is smart enough it might elide the automatic expansion of type width
since it makes no difference.  

Robert

1- This is logically equivalent to what you are doing but very few
compilers are capable of optimizing the if statement to a masking operation.

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