# I2C vs I²C, naming convention

Some questions involving I2C have been edited to I²C. They refers to Inter-Integrated Circuit, according to Wikipedia, is pronounced I-squared-C, a multi-master, multi-slave, single-ended, serial computer bus invented by Philips Semiconductor (now NXP Semiconductors). It is typically used for attaching lower-speed peripheral ICs to processors and microcontrollers. Alternatively I²C is spelled I2C (pronounced I-two-C) or IIC (pronounced I-I-C)

What is the preferred spelling on EE.SE? Should spelling being i2c, I2C, or I²C, or something else?

The recent edit to I2C bit banging is why I bring this up. Even the url is not handled correctly by the SE system, as the ² breaks the automatic url recognition. A search for i²c will only bring up results for IC.

• I brought up the search issue on Meta here: meta.stackexchange.com/questions/270111/… Nov 28 '15 at 11:04
• The side issue here is that just changing from one form to another is a trivial edit.
– W5VO
Nov 28 '15 at 17:14
• Don't forget TWI. Dec 4 '15 at 22:51

Spelling should be I2C, as I²C is not searchable. While I²C may be the correct spelling, SEO and in site search-ability should be preferred.

• Since I can't upvote my own answer, consider this +1 Nov 28 '15 at 8:56
• Checking the tags: i2c exists, iic does not exist, [tag:I²C] isn't even recognized as a valid tag. So I'm inclined to go with the simpler, more commonly used spelling. I'm not even sure I can roll my typewriter's platten up to make the superscript... Seriously though, I've only ever seen the superscript version used in marketing materials; all real source code I've seen or written on this uses plain "I2C" (or sometimes "two-wire interface" for those worried about infringing Philips' patent). Nov 30 '15 at 7:07
• I2C is far more common than IIC. A google search for "iic bus" turns up a full page of "I2C" results. Dec 2 '15 at 20:21
• The spelling of the tag is "i2c" so it is searchable. Dec 5 '15 at 23:13
• @peter only if tagged i2c. Dec 5 '15 at 23:15
• -1, I²C is searchable. Dec 6 '15 at 12:37
• @AndrejaKo no its not, it returns results for IC, not "I²C" or "I2C". Dec 6 '15 at 15:33
• @Passerby In my case, using Google and Firefox, it doesn't. It really does return results for I²C, with I²C being the bolded search term in results. Dec 6 '15 at 19:36
• In Google I²C is searchable and will return both I²C and I2C results. On EE.SE it isn't. But it doesn't really matter as long as things are properly tagged. Anything with i2c, will appear when I2C is searched whether or not the body of the text contains I²C. Dec 6 '15 at 20:38
• @andrejako using the SE search on android chrome, and os x safari, I²C does not come with I²C results. Your using Chrome on windows I assume? Could you provide a screenshot so I can add it to the bug post? With the address bar showing. Dec 6 '15 at 22:50
• @Passerby Sorry, a bit of miscommunication here, I'm using Firefox on Windows and Google search. I never could get usable results from SE search. Do you still need that screenshot? Dec 6 '15 at 22:57
• Ah, nope. I know Google works fine. It's se that's the issue :) Dec 6 '15 at 23:00

Spelling should be I²C, as I-squared-C is the technically correct spelling, SEO and search-ability be damned.

• While in source code I use I2C because I don't want to break compilers not handling ² correctly, everywhere else I use I²C because that's how it is called. Seems like I have to treat the URL parsing engine as a compiler if I ever end up writing a question about this. (But for me that's more like a bug and should be fixed on SE, I mean we live in the age of unicode and stuff...) Dec 3 '15 at 12:27
• @Arsenal actually, ² is a valid unicode character, and all browsers should handle it (the question, before re-editing had ² as part of its url and it would still bring up the correct question). Even Google search handles it correctly, returning both ² and 2 results. It's a bug in the SE search, and I have brought it up on Meta.Se meta.stackexchange.com/questions/270111/… Dec 3 '15 at 12:33
• Seen that and up-voted it. Dec 3 '15 at 12:36

Peronally, I write it as IIC, and have done so consistantly here on EE.SE. It stands for "Inter Integrated Circuit". I dislike cutesey abbreviations like I2 for double-I.

It should be plenty clear enough what IIC means, it's nicely searchable, and more accurately indicates what it's abbreviating anyway. Cutsey "squared" notation be damned.

• Of course, that's not how Phillips/NXP calls it. It's been I2C/I²C since day one. So by using IIC instead of I2C, your doing what you typically hate, re. Arduino "Shields" and "Sketches". Nov 28 '15 at 13:31
• llC bus, for your limited liability corporation communications?
– W5VO
Nov 28 '15 at 17:18
• tmsearch.uspto.gov/bin/… Nov 29 '15 at 4:27
• @Passe: No, Phillips is doing what I hate, which is misusing a mathematical construct for their own marketing purposes. The abbreviation stands for Inter-Integrated Circuit, which would normally be abbreviated IIC. They decided to expres II as I-squared, which is totally inappropriate since the two "I" don't represent variables that are being multiplied. It's obnoxious marketing, although not as bad as the arduino name "shield". Nov 29 '15 at 14:59
• If you don't like their marketing, call it TWI like most manufacturers (other than Phillips/NXP) do to avoid legal issues. I²C (I2C) is the correct trademarked name, so whether you like it or not IIC is not correct. Dec 2 '15 at 18:22
• remember EEPROM, aka E²PROM. there is precedence in using ...² with regards to abreviations in engineering. Doesn't matter if you don't like it, it is done and has been done for a very, very long time. Dec 3 '15 at 17:14
• I don't think it is a big deal, since most electronic naming conventions were already hopeless nonsense to begin with, before the abbreviation is invented. Just what is an "inter integrated circuit"? Something that communicates between different integrated circuits... why thank you Phillips, that's very descriptive! "Serial Peripheral Interface", "Controller Area Network". It's like some branch competition over who can come up with the most nonsensical name. Dec 9 '15 at 10:23

Spelling should be i2c, or IIC, or any other version. While acronyms tend to be capitalized, and IIC tends to be somewhat recognized, the other two options are not good for some reason.