Which USB to serial adapter should I buy?

black is the ground colour.


Thought this too, but then the colors of the cables are crossed, which is no problem actually.

So I have to remove +5V and 3,3V. Which colors are the correct colors for TXD amd RXD?

The color is not important the position is important

Are you making your own cables?

That is clear, but I would like to know if the pins have assigned colors normally?

The cable on the photo as included, when I bought it.

Don't overthink it…

If you use it more often, it might make sense to rip the leads apart - so you can attach the individual leads separately (easier to work with, not quite as rigid; the unused connectors not flapping around/ getting into the way). Aside from GND (for which black and/ or white is a natural choice), the colours really don't matter - you're never going to connect 3.3V or 5V anyways and rx/ tx need to be shuffled around as needed (until it works).


There is no standard, just a common practice that has white and green for RX and TX. Beyond that there is no understanding about which one is which since RX on one side becomes TX on the other and vice versa, one side will always have them turned around.

Your header has two pins carrying voltage, maybe that's why they didn't include a red wire to clearly indicate VCC. Which is actually smart because there's a 50% chance a red wire could carry the wrong voltage. To avoid confusion you should definitely put black on GND (that's as standard as it gets), and that frees your white and green (light green? or is that grey?) for RX and TX.


The colors appear to originate from the resistor color code. They have no meaning with regard to Rx or Tx.

As others have said, use black for GND, and choose among the other colors for Rx and Tx. I suggest using colors with good contrast, i.e. not the combination of white and grey.


Thanks, that is a good idea.

Not to harp on this point too much (in the end, for all the devices care, the wires could all be shades of pink), but now I'm intrigued as to how you came to that curious conclusion.

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"Rainbow" ribbon cable very commonly uses the EIA resistor code, the last half of which is on the cable posted.
Blue = 6
Purple = 7
Gray = 8
White = 9
Black = 0


Interesting, I was not aware that rainbow cables did that (or I never noticed.) Thanks. The black one stands out then, but it may be simply "wrapped" around to zero.