Question

Okay, here’s what I’m trying to program in C.

I have an 8bit binary signal from an ADC on an ATmega32.

Now I want to convert that signal into an bar with 15LED’s that increases the higher the input value is.
So basically I want to cut my 8bit signal down to a 4bit one, convert it to decimal and show it at an increasing bar.

I first had the idea to check if my input is in a specific range (which would be always a range of 255/15) but I just couldn’t figure out how.

Just checking if the input is higher than a particular value won’t work because in that way there could be more than one condition at a time true.

Have you any idea how I could solve that? Any help is highly appreciated. 😉
Thank you!

Answer 1

Use this:

uint8_t adc = GET_ADC_VALUE();

// Say LED is a 16-bit register

LED = (adc ? (1U << ((adc >> 4) + 1)) - 1 : 0x000);

So only ADC value 0 has all LEDs off, all other ADC values power on 1 to 16 LEDs. This has the advantage of not using any division (ATmega has no divisor instruction).

EDIT: The above code actually assumes 16 LEDs, if you have 15 LEDs just do:

LED= (1U << (adc >> 4)) - 1;