C arrays, etc

[Colt45]

I'm working on a little project that involves a 10bit ADC.

I want to take the adc value and then read the output value off an array.. simple enough.


but... I don't need the 10bit accuracy. a 1KB array is kind of excessive when 100B would be accurate enough. (not to mention I've only got 8KB of ROM)

so would the best way of doing this?
I was thinking to take the ADC input, divide by 10 and then read that off a 102 byte array?
Or is there an easier way?

I'm not terribly good at this so any ideas would be good 🙂

or is there a short way of writing an array with duplicate values? i.e. values 0 - 20 (out of 1024) are all 0xFF or something like that.

thanks

 

[DaveSimmons]

It's binary so you'd want to /8 (128-element) or /16 (64-element), which you can do by shifting right 3 or 4 bits.

 

[notfred]

Yeah, do what Dave said, shift right by few bits. Each bit will divide the total by two, so shifting right by 1 will give you 512 values, by 2 gives you 256, by three gives you 128, and by 4 give you 64.

value >>= 1; // or 2, 3, or 4

 

[Colt45]

Sounds good - I really should have thought of that.
I guess I did post it at 3 AM. 😉

thanks guys.