Electronic – The difference between Atmel ATmega16u2-MU and -MUR

There isn't really much difference there may be some differences in which chips are supported under Codevision so you may want to check for the chip you plan to use.

There are different IDE's available Codevsion has its own IDE and there are different IDE to choose from for Atmel's avr C (like AVR Studio 4) But you could also use WinAVR which is uses GCC, or you could use GCC with another IDE of your choice or you can go without the IDE entirely. If you do use GCC this is a good website to check out AVR Libc. For even more information and tutorials about AVR you should check AVR Freaks.

No assertions from me :-) - I don't know enough about this cpu to assert anything. The following is based on experience, the datasheet and a good helping of guestimating.

Summary: Not enough data BUT

• 200 +/- 50uA/MHz + allowance for activated peripherals as per Table 7-6 p46 in datasheet

Copied below.

In your position I'd

• Lean heavily on Atmel.

• Do some measurements myself.

• Refine the rudimentary method suggested below.

Interestingly, the total of peripheral currents below sum to about 100 uA/MHz so the core consumption predominates. This suggests

• a minimum of about 150 uA/MHz (a bit less than 165) and

• a maximum of about 360 uA/MHz (based on the two ill defined datasheet examples = 260 + 100 from table).

I'd not lightly dismiss Fibonacci numbers as a "light load".
A significant portion of the current drain for a CMOS processor comes from charging and discharging capacitive nodes, whether memory bits or port pins or registers or whatever. Anything that causes more bit changes is liable to require more power. I don't know why their division routines is lower powered, but something that "just adds" is potentially able to change as many bits as most things.