General > General Technical Chat
'Master' and 'slave': Tech terms face scrutiny amid anti-racism efforts
PlainName:
--- Quote ---It's never clear whether TX on a schematic is the *transmit out*, or *transmit signal in*.
--- End quote ---
It should always be out on a DTE (terminal), in on a DCE (modem).
If you have a problem with that then you'll also likely have a problem with the master/slave style too because you need to know which is the master and which the slave to work out what's in or out.
PlainName:
--- Quote ---TX is always output, RX is always input. Using name "TX" as "transmit signal in" sounds like an error, unless it's just a signal between the transmitting device and the physical interface driver chip.
--- End quote ---
I'm going to be diplomatic here: wrong wrong wrong wrong wrong wrong. And it's wrong :)
madires:
There are more problems with banning words. It's censorship! Those who want to rename an SPI master or a master branch because they think it might be racist are actually trying to enforce censorship which makes it even worse.
Siwastaja:
--- Quote from: dunkemhigh on June 21, 2020, 01:14:16 pm ---
--- Quote ---It's never clear whether TX on a schematic is the *transmit out*, or *transmit signal in*.
--- End quote ---
It should always be out on a DTE (terminal), in on a DCE (modem).
--- End quote ---
This is a source of confusion.
DTE/DCE classification is a higher level standard introduced by IBM, between computers or terminals, and modems, implementing kind of "master/slave" roles I specified above. Note, flow control is added as well. They arbitrarily decided to connect "TX" to "TX", and "RX" to "RX", so that you have to know the role (DTE vs. DCE) of the devices; only after that you can "simply" connect wires with same names together; and connecting DTE to DTE requires a special "crossover cable".
But all of this is utterly irrelevant, and only serve to confuse, in most use cases where "UART" interfaces are met today, where they are just bidirectional data links, nothing less, nothing more, and it's completely up to the designer of the higher level what relationships to introduce, under what terms. Younger generation designing UART things all the time know do not even have a freaking idea what we are talking about. So, copying the DTE/DCE terminology is not a sane choice when, for example, communicating between two microcontrollers on a PCB. If you want to take the IBM terminology, I suggest you use the typical 9/25 pin D connector types as well, with stickers showing whether your devices are DTE or DCE. Quite a niche today, really.
In this sense, we are both correct and wrong; just talking about different layers. To further clarify, my initial comment is neither right or wrong; it's not an official standard, it's a suggestion and describes how I and many others name things, and I truly think it's for the least amount of confusion. (Always when in doubt, be explicit; hence "cpu_to_modem" for example!)
madires:
When you want to connect two DTEs you simply use a null modem cable. ;) BTW, the gender of the DB9/25 connector already indicates if it's a DTE or DCE.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version