ESP8266 Community Forum

- Thu Dec 11, 2014 4:48 pm #4611 OK, am I being a total idiot (please don't answer that!)

I have been communicating with the ESP, sending AT commands to connect to my local network and generally playing about. I have just started to disconnect her and noticed that I have TX on the ESP connecting to TX on the TTL (and RX to RX). I am sure this is wrong, it should be RX-TX, TX-RX. So just in case the silkscreen on my TTL is erroneous, I connected her up to the Arduino (which does need the ATMEGA removed to talk serial); sure enough, this device will only communicated TX-TX, RX-RX!

Kind Regards,
Harold Clements

ICQ: 621094716

- Thu Dec 11, 2014 5:21 pm #4612

OK, am I being a total idiot (please don't answer that!)

OK , I won't!

Just to make life more interesting SOME hardware suppliers label their serial-out ports TX, and SOME label them RX. If you're interested it depends wether they consider their HW to be DCE or DTE (Google is your friend).

Many, many, many of our tinkering colleagues, and ICT professionals have fallen in the deep pit, you've fallen into. Haven't you seen the bones in the pit, now you now where they came from.

My advice is to ALWAYS distrust RX/TX pin-labels of serial ports and TEST yourself, and READ in the doc what the serial-out and serial-in of the equipment is.
- A simple LED+resistor or multimeter will show activity on the serial-outline line.
- remember my "jiggling 3.3V to the serial-in line" to make sure that you get the INPUT-line, thats why!

Maybe you made the mistake for the first time, believe you me, it will probably not be the last time!

Isn't electronics fun!!!!

- Thu Dec 11, 2014 5:37 pm #4614 Again, an excellent explanation of which I am extremely grateful for.

Thank you once more,
Harold...

Kind Regards,
Harold Clements

ICQ: 621094716

- Fri Dec 12, 2014 12:50 am #4625

SOME hardware suppliers label their serial-out ports TX, and SOME label them RX. If you're interested it depends wether they consider their HW to be DCE or DTE (Google is your friend).

in general, a usb to serial boards are DTE.

I have just started to disconnect her and noticed that I have TX on the ESP connecting to TX on the TTL (and RX to RX). I am sure this is wrong, it should be RX-TX, TX-RX.

can you post a picture of your usb to serial, so other guys here can be warned about how it is labeled, in case they have same usb to serial.

i have seen some boards where TX pin is labeled RX, and vice versa. and makers have good reason for it.
common ones, most labels are describing the pin itself. whether it is TX or RX pin.
and there are labels, describing which pin is to connect to it. TX pin is labeled RX, because the label RX, is not to describe the pin itself, but to tell users that it is where you connect the RX of the device to be connected, in our case, RX pin of the lovely ESP8266.