SPI pins renaming to avoid casual references to slavery?

We are in the midst of many racial conflicts right now and IMO it could all be avoided by simply not talking about racism at all.
Frankly, I’ve never associated the pin names MOSI/MISO with slavery, not even unconsciously, but some people think otherwise and soon we might see COPI/CIPO pin names instead of MOSI/MISO on new datasheets, .

What are your thoughts on this?

This is craziest idea i have ever seen. this is only going to create more confusion when design schematics, create another TX/RX situations, destroy 40 year old traditons and for what? because in the US some people had slaves centuries ago? “Master” and “Slave” in SPI Specifications never associated with actual slavery. They were named that way because roles and way “master” and “slave” was interacting with each other, because in electronics SPI controlled “Slave” can’t do anything without “Master” command. Word “Controller” and “Peripheral” are already in use in electronics in different meaning and this is going to create only confusion and it is not going to simplify anything. It is going to make documenation harder to read. “MISO” and “MOSI” are clear in any sitations and any SPI modes which can not be told about “COPI” and “CIPO”.

This not about inclusive community, “MISO” and MOSI" does not prevent anyone to become engineer. This is artificially created problem by incompetent people for only one reason! CONTROL! If this change actually happens, in future it will be used to cancel people because they didn’t used correct wire names.

What will be next? “Mastercard” will be declared racist and will be renamed as “Controllercard”?

We don’t need politics in science and engineering!


100 %.

I think it’s an interesting idea.

Tech is a very homogenous group - in my experience, it’s overwhelmingly white, male, straight. I think, as a result of that homogeneity, it makes us a little blind to details outside of our own lived experience. As an example: when was the last time you had to think twice about going to a bar alone as white, straight man? It’s not something that anyone can do in complete safety. Don’t take my word for it - ask any twenty-something woman who’s tried online dating.

I think that this naming convention is something that’s not a big deal to most white people, but I also think it sends a message about what we, the engineering community, care about and prioritize. It makes me wonder, idly: “Who has chosen to stay away from engineering because they received a signal that we’re not inclusive?”

1 Like

What does race and sexual orientation have to with electronics? This names doesn’t make engineering community (idk what this even mean) any better. this is only going to make matters worse. if this actually passed in several years we will see master and PhD Dissertations banned because “They didn’t used correct language in SPI Documentation”

This is about CONTROL!

You’ve emphasized the word control in two posts now. It is almost as if you’re sensitive to being enslaved by a master.

Joking aside, I’m not getting your point on “if this is actually passed”. We’re discussing convention and norms, not a law as far as I understand the conversation. Society evolves.

As far as engineering goes, why care if something is relabeled? As an engineer, I’m far more interested if functionality changes.


If people tell me that my use of a technical term has other meanings and makes them feel bad in any way, I believe them and think of things I can do to avoid using that term. It seems very simple really - the cost to me is very small, and I’m told that it benefits other people (for reasons that make sense), so … why not? It’s not politics - it’s just being kind to other people.

As for being confusing, if you can cope with TWI being a pseudonym for I2C, you can deal with COPI being a pseudonym for MOSI.


Changing the names seems like a mild inconvenience.

There’s a question of where does this end? Do we ban the words master and slave entirely?

The truth is that they’re useful in this context to describe the relationship between two communicating devices. Nothing more. Anyone who makes a relation between this and human slavery is being a little silly in my opinion.

I don’t see why someone would be offended by that, without also being offended purely by seeing those words.

That said I’m a fairly privileged male who’s never had to do deal with any issues of slavery so I’m aware I might not have the whole picture. If there’s a general consensus that this needs to be changed, I’m somewhat agnostic as long as the replacement is equally descriptive and easy to use.

1 Like

Every leftist propaganda is starting like this. first they say “lets discuss it” then it becomes “Problematic”, after that “It is offensive” and finally it “Racist, it must be terminated”.

SPI protocol exists 40 years already and suddenly it became offensive? in election year? “Master” and “Slave” is very widely used term in electronics and you want 40 years of work rewritten?

Now they are offering us words “Controller” and “Peripheral”. “Controller” and “Peripheral” are already widely used terms in electronics e.g Microcontroller, HDMI Controller, UART Controller etc. and now we are designating lines with it. Imaging you are designing complex system with UART, SPI and I2C protocols, those word are main terms used in UART and I2C. This is going to make reading datasheet nightmare especially for students and young engineers who are just learning those protocols.

But really frightening part is that this is not about fighting against racism it, end result of this will be censorship in thesis publications. They will ban you work because “you used offensive language” by labeling you schematics “MISO” and “MOSI”.

If someone feels bad because 40 years old protocol is using words “Master” and “Slave”, they better deal with they complexes rather than redefining language and standards.

This is not about making electronics more convenient (which it clearly does the opposite) this is about specific political agenda infiltrating science and engineering.

@PavleTsotskolauri, @yosheli, welcome to the forum. To you and to everyone, I’m fine leaving this post up, but let me be the first to say that I will not abide by any hateful language here. Even excited language, I really don’t have the patience for. This is a place to discuss electronics in a calm, civil manner.

I’ll be honest, I had a small bit of a reaction when I first read about this, but only because it was unprompted. “That would be an inconvenience!”. But once I stopped and thought, ‘OK, so now it’s COPI and CIPO’, my brain settled right in.

I think we should actually be talking about their recommendation to switch to "SDO’ and “SDO”. That, in my opinion, is the only offensive thing in the statement. The _I_O, _O_I is the real innovation, let’s keep that. Because I mess up my in’s and out’s a LOT.


Some people here need to calm down. This isn’t about control, taking away anything from you, or any other conspiracy-laden whinging that comes with it. It’s about empathy and making people feel more comfortable while engineering. How is that so hard to recognise?

Hello @ChrisGammell

can you tell which was the hateful language that i used?

The IEEE have been discussing the use and replacement of master/slave within an engineering context for many years. This isn’t a left/right/election conspiracy, but rather a genuine attempt at using clear language in a consistent way.
Both language end engineering evolves over time, and there are many new situations where this kind of relationship needs to be referenced, and the really problematic issue is that (in the English language) there isn’t such a clear and universal word-pair as master and slave to replace them. Whether we like it of not, these words do have a significant amount of baggage, so finding alternative words seems like a sensible move. This doesn’t imply any consequences for what already exists, simply finding a better way to communicate in the future.
To put this into context, every journal has a style and language guide that authors must follow, and have done since they started - is this censorship too?


Yeah, I mean I don’t really hold a strong opinion on this. I don’t understand why it is a big issue, and my question is are we going to forbid the use of those words in other contexts? Removing the words does not remove the awful history unfortunately.

But @Liivatera puts it well when they say there is baggage with Master and Slave. I agree with that. If a substantial portion of existing/new engineers feel uncomfortable with it, then it’s an issue whether I think so or not.

Changing them? Well… since it’s a really easy thing to do, I guess it’s not really a problem. Though I feel sorry for whoever has to go digging through decades of legacy datasheets to make the change haha!

1 Like

Maybe hold some kind of vote on it to decide, then implement it pro-actively to all new technical documents.

Then give some level of understanding to retro-active uses of the terms so that people aren’t penalized for using the old terms if it’s what they’re used to.

That seems to me the most logical and balanced approach.

1 Like

I wasn’t accusing you of that. I was saying that this is a charged topic and I’m not going to allow language I deem unsavory.

I’m indifferent, I don’t understand at all what it really solves but then again, not a hill I’m even remotely interested in dying on.

Yes this is a hot topic (among many others), I think it is good to allow/have a respectful, lively discussion about it: differing opinions as long as they can be debated w/o personal attacks. This is a lot of what we lost in current culture or it being suppressed now causing extremism to be the only route.

There is so much irony these days, sometimes I just want to cry, I literally read some twitter threads yesterday condemning the police about not doing anything about a drive by shooting at Seattle’s CHOP zone.

IMO, it sucks that having a conservative ideology must draw a direct inference to intolerance. I like to be free to live my life, respect others, be respected and pay low taxes.
If only everyone was an engineer so they would be inherently wired to solve problems :slight_smile: (I’m way to much of an idealist)

1 Like

so you don’t go out to many bars in the glasgow gorbals then? :wink:

sdo/sdi/dout/din is pretty common.

I’ll note that avoiding Master/Slave doesn’t require changing the letters of the acronym; At work we’re switching over to using Microcontroller Out Sensor In / Microcontroller In Sensor Out

As for why: Because I really don’t care what sequence of letters is on my schematic as long as I can understand what it’s communicating, and if that is a little thing I can adapt to that will make someone feel more welcome and comfortable in my community, WHY THE HELL NOT.

As a card carrying member of The Majority™ in this and most contexts, it’s easy to dismiss or not even consider things that would give others pause, which means the environment that grows up organically around me and others like me is a reflection of our concerns.

Imagine an EE community made up of exclusively of former slaves and their descendants. They almost certainly wouldn’t use Master/Slave as part of their technical lexicon because they would make the conscious choice to use something else, and this one small “inconsequential” change would combine with others to create an environment different from ones grown around people of a different background.

Now imagine an prospective EE that comes to a crossroads and sees both groups; one that has changed something that they don’t like, and another that didn’t care to think about it or decided it didn’t matter. Maybe this EE prospect wouldn’t notice the difference and would choose a community based on some other criteria. But maybe they do notice, either because they come from a people who were enslaved, or for some other reason.

Consciously or unconsciously one group will almost certainly be more welcoming to them than the other. I know one of these communities exists, and I’m doubtful about the existence of the other which means there are a whole class of people that will not feel as welcome as they could in our community and why? Because we couldn’t be bothered to change something that we didn’t care about until now?

I know there are certainly some now that are saying to themselves “well if something so small would keep them out of engineering, clearly they probably shouldn’t be one anyways” or some other gate-keeper-ey bull, to this I say: you literally have no idea what such a person is capable of so maybe wait until the data is in before making a decision. You know, like an engineer.