alt Hacker NewsI 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 whatever), or different cable sizes for each.
3. Automatic type detection - TTL/RS-232, RS-422, RS-485, or different connector types by each.
Ideally I'd do this on a 8p8c or 10p10c connector, because of ease of making cables, with various resistance values across pins 1-8, or 1-10 to tell you what kind of interface it was.
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That sounds completely useless. Who needs a standard that is not actually standardizing anything?
If you are willing to design a board with with 8p8c connector, identification resistor, and protection parts, then you might as well put RS-232/RS-422 transceiver. Those are very cheap nowadays, might even be cheaper than the connector itself. And you standardize on crossover cables, there will be no need DCE-DTE detection.
(Not that anyone would need this today. If you are connecting to existing serial port, there is USB, and USB-serial adapters are very cheap. And if you are designing a serial-based communication system, say for the robot, then CAN or RS485 are much better choices)
you are over-engineering it. At the end of the day, it's a debug connector, when you use it, you should know what you are doing. The more thing you add to debug connector, the more thing you have to debug when the debug connector not working.
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
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 (let's say 0402 or even 0201) and left those out too to save the last 0.01 cent.