General > General Technical Chat

'Master' and 'slave': Tech terms face scrutiny amid anti-racism efforts

<< < (133/352) > >>

Siwastaja:

--- Quote from: dunkemhigh on June 21, 2020, 02:29:50 pm ---
--- Quote ---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"
--- End quote ---

Exactly the same with MOSI. You have to know if that bit of kit is a receiver or transmitter, master or slave, sender or consumer

--- End quote ---

No, no! MOSI always connects to MOSI, MISO always connects to MISO; the names are the same on typical master devices (like microcontrollers), and slave devices (like sensors). That's the whole point. No crossover connections ever needed.

That shifts the responsibility elsewhere, though: to the chip interface designer. They need to know that if they are designing a master, MISO will be an input, but if they are designing a slave, MISO will be an output.


--- Quote from: dunkemhigh on June 21, 2020, 02:32:01 pm ---You need to know whether a device is a master or slave, no? And when a microcontroller can be a master and slave, what is the pin function with the label MISO?

--- End quote ---

If the microcontroller is master, MISO is input: "master in"; if the microcontroller is slave, MISO is output ("slave out"). The great thing is the specification is fully supplied in the name itself, so it's very easy to remember. That's exactly the point about "explicit". The IBM TX/RX naming carries a hidden viewpoint which isn't in the name.

PlainName:

--- Quote ---If the microcontroller is master, MISO is input: "master in"; if the microcontroller is slave, MISO is output ("slave out"). The great thing is the specification is fully supplied in the name itself
--- End quote ---

I will hold my hands up to saying that completely passed me by, presumably from not actually using a masmicro as a slave - the MO has always been out.

Siwastaja:
I regularly use microcontrollers in both master and slave configurations for SPI.

Although master obviously is a more common configuration because that's what you use when interfacing with most existing chips, like sensors, displays, etc.

SPI is great for transferring memory structures between two microcontrollers, usually with DMA, so that both parties can work "almost" like it was a single-MCU solution. In this case, one of the MCUs is obviously a slave, but both equally share their memories, the only difference is that master is the one driving the clock and chip select. (STM32 chips, for example, add a support for hardware checksum generation and checking, to make such use case more robust.)

magic:

--- Quote from: SilverSolder on June 21, 2020, 11:12:02 am ---Perhaps the best systems just provide a framework to let people do their own thing...

--- End quote ---
At some point those systems inevitably start to believe that radicals are people too and then the fun begins ;)

retrolefty:
 My memory of the RS232 standard ( DTR, RTS, CTS, etc) was an ATT definition dating from the 1960s, IBM had nothing to do with it. In those days one classified a specific device as a terminal device or a communication device, where a 'computer' was not specifically defined as either one, as a computer could in practice be hardwired to terminals or modems or both.

 As a field engineer in the 70s I was often required to wire serial links between different manufactures devices and it was almost always a hassle without schematics to determine if a given device's connector pin wired to a physical electrical input or output. Many times the control pins were not even used by a device so things like flow control didn't even function and if needed would depend on software flow control using Xon/Xoff ASCII characters if supported by both sides on the link. Also connector gender did not define it's classification as male to male or female to female cables would often have to be made.

 Bottom line is the setting up RS232 links was mostly a snake pit/ time sink that the SPI interface naming solved.
 nicely. 

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod