Flaw in code and I can't find it?

[ScruffR]

@ridgerunnersjw

int *p_a;
int a[4];

p_a = &a[0];

Are you absolutely sure this is where the error is flagged?
Since this code builds absolutely fine for me I'm pretty sure you have some other code that fails instead.

@ScruffR

As we already said, without seeing your entire code we won’t be able to spot your error.

BTW, in your calculation

@ridgerunnersjw

avg[sensor] = ((float)(sum))/NUMBER_SAMPLES * 3.3/4096;

You have an off-by-one error.
You'd need to divide by 4095 since the maximum reading of the ADC would be 4095.
For a full amplitude signal the division should result in a factor of 1 but 4095 / 4096 will not give you that.

Also a slight reorder of that calculation will make it slightly shorter and also more "precise"

avg[sensor] = (3.3 * sum) / (NUMBER_SAMPLES * 4095);