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The Serial TTL connector we deserve

kohlschuetter.github.io

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Re: The Serial TTL connector we deserve

#21

Post by Geof25 »

Aloha wrote: post #18

I would tell anyone who is doing a new traditional serial connector/cable to add the following - 1. Automatic DCE-DTE detection and an interface which will rewire itself as needed to be the correct way, or you automatically know DCE vs DTE by connector gender. 2. Automatic Voltage Detection - 232 levels, TTL 5v, TTL 3v - and interfaces that are isolated enough to deal with the wrong voltage (clamping diodes or whatev…

What you are describing is going to be nightmare to work with - i.e. when you will have automatic detection of levels and it will decide to push RS232 into 3V3 MCU then you will have dead, maybe one of the kind prototype or dead expensive production device

Re: The Serial TTL connector we deserve

#23

Post by Geof25 »

wildzzz wrote: post #13

Ideally you wouldn't need to expose a TTL serial debug port to begin with. Maybe on a prototype you would want this but I'd rather just have a single connector that can expose everything (jtag or swd). Bonus points if the interface chip is on the board so it's just a USB port

Well the first problem you will hit I'd that very likely you will need to protect or isolate those lines from ESD. This will raise price of device and it will get denied just in these grounds.

Re: The Serial TTL connector we deserve

#24

Post by foresto »

eqvinox wrote: post #12
foresto wrote: post #10

Earlier quoted context omitted.

They're not random connections; they're predictable. I'm not worried about Tx briefly touching Rx or ground in these devices.

Random in the time sense. You'll get junk on your serial line, depending on the scenario that can matter a lot.

My scenario is connecting terminal emulators to getty or u-boot, which I think is a common one. A blip of line noise when plugging in would be barely considered an annoyance, easily cleared by pressing Backspace.

But yes, if someone happens to be using their serial line for some kind of sensitive signaling, then I would agree that choosing a more isolated connector (or just avoiding hotplug) would make sense.

Re: The Serial TTL connector we deserve

#25

Post by eqvinox »

foresto wrote: post #24
eqvinox wrote: post #12

Earlier quoted context omitted.

Random in the time sense. You'll get junk on your serial line, depending on the scenario that can matter a lot.

My scenario is connecting terminal emulators to getty or u-boot, which I think is a common one. A blip of line noise when plugging in would be barely considered an annoyance, easily cleared by pressing Backspace. But yes, if someone happens to be using their serial line for some kind of sensitive signaling, then I would agree that choosing a more isolated connector (or just avoiding hotplug) would make sense.

Thing is, for a serial TTL connector to become ubiquitous, it needs to cover at least something like 99% of scenarios. Or maybe 95%. 3.5mm TRS ain't that, and thus just increases general diversity in connectors.

Re: The Serial TTL connector we deserve

#27

Post by Aloha »

Geof25 wrote: post #21
Aloha wrote: post #18

I would tell anyone who is doing a new traditional serial connector/cable to add the following - 1. Automatic DCE-DTE detection and an interface which will rewire itself as needed to be the correct way, or you automatically know DCE vs DTE by connector gender. 2. Automatic Voltage Detection - 232 levels, TTL 5v, TTL 3v - and interfaces that are isolated enough to deal with the wrong voltage (clamping diodes or whatev…

What you are describing is going to be nightmare to work with - i.e. when you will have automatic detection of levels and it will decide to push RS232 into 3V3 MCU then you will have dead, maybe one of the kind prototype or dead expensive production device

Depends on what you make the default as.

Re: The Serial TTL connector we deserve

#28

Post by Aurornis »

amelius wrote: post #16

I always wonder why Molex makes only black and white connectors. This makes it needlessly difficult to use different connectors for different purposes. Same with phoenix contact but there it's mostly green terminal blocks. Is it so difficult to just offer some more colors?

They’ll make them in any color you want if you order enough.

Adding more colors would multiply their logistic and inventory requirements, which are already hard with so many different connectors multiplied by number of pin options. Multiplying that even further by number of colors that most people would never buy isn’t a win.

Re: The Serial TTL connector we deserve

#29

Post by Aloha »

eqvinox wrote: post #19
Aloha wrote: post #18

I would tell anyone who is doing a new traditional serial connector/cable to add the following - 1. Automatic DCE-DTE detection and an interface which will rewire itself as needed to be the correct way, or you automatically know DCE vs DTE by connector gender. 2. Automatic Voltage Detection - 232 levels, TTL 5v, TTL 3v - and interfaces that are isolated enough to deal with the wrong voltage (clamping diodes or whatev…

At that point it's not a debug connector anymore. Note there's a pseudo-standard for V.24/RS232 on RJ45 already, and nobody uses it for debug connectors since (a) you'd need a RS232 transceiver and (b) RJ45 connectors are honking huge. The point is to shave off the last cent, which is why you get a possibly-unpopulated 1×4 or 1×3 2.54mm header. Bonus points if the manufacturer designed series resistors into the board…

I'm open to other options, the biggest things is DTE-DCE auto detection

Re: The Serial TTL connector we deserve

#30

Post by russdill »

eqvinox wrote: post #6

The only things with a chance at succeeding in this space are putting USB-serial directly on the board + USB-C, or alternatively bluetooth classic RFCOMM profile. (The latter is a very long shot.) Apart from that, this doesn't even touch upon the various voltage levels for logic-level serial ports, or the question of whether to Vref or not to Vref. (Or RTS/CTS.)

Microcontrollers that support BLE are getting so cheap this really is becoming an option. Hopefully with some button that activates it.
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