GPS NEO-6M and resistors to RX/TX pins

[ericvill]

Good evening, everybody,

I have read in various blogs that resistors might be hooked between an Arduino unit and a Neo GPS unit...

GPS - Neo 6M V2 Supply & Logic Voltage Question

I'm considering switching an Arduino project over to use 3.3v Arduino Pro Minis. Currently I use the 5v variant. I believe this will have a side benefit of eliminating 2 resistors, but I wanted to check wtih you guys first. The Neo6m I am using specifies 3-5v supply voltage. Currently I have it hooked to 5v. And, I have 2 resistors hooked up to Neo's Rx pin (10k->GND, 4.7k->data). I saw a lot of examples this way, so that's why I did that. Looking at example configurations online, I see: 3.…

Might have fried NEO-6M GPS?

I am using an Uno, connected Vin to a 12v lead acid battery (no car involved). That is a little outside the recommended voltage I know, but it is simple and has worked okay for most of my experiments. For this experiment I connected a NEO-6M GPS, on an XBee shield, to the 3.3v arduino output, along with the proper ground and I used software serial on pins 11 and 12 for RX & TX pin connections etc. All of these things I learned from this forum, thank you all. I got good data sent to my computer …

and a few other links...

Hence, my question is as follows...
Does one need these resistors if the NEO6M GPS VCC is wired to the 3.3v (pin)?

Argument...
The GPS module is "only" sending information to the Arduino unit (in my case... a NANO)
The RX pin on the Arduino unit (hooked to the TX pin on the GPS module) does not send anything out, and, logically, there cannot be any voltage as this pin receives information from the GPS module.

I hope I have not been too folded into myself and I missed adding resistors to the GPS module in question...

I hope I could explain my "problem" well enough...

Any concrete ideas (or solutions)?

Thanks a lot,

Eric

[hmeijdam]

I use that connection without any resistors and it works fine. Your NEO will send out a serial signal switching between 0 and 3.3V. 3.3V is enough to be seen as a HIGH level by your Nano, even if the nano is running at 5V.

Sending a 5V signal from the TX pin of your Nano to the 3.3V running Neo may not be a good idea, but you are not making that connection. So only GND and the TX pin from the NEO are connected.

Keep in mind that the 3.3V pin from your Nano may or may not have enough drive strength to power your GPS module. If the 3.3V is taken from the CH340G or FT232RL chip it is very weak, intended as a 3.3V reference. If your Nano has a separate 3.3V regulator it might work.

[ericvill]

@ hmeijdam
Thanks for your answer

That is what I thought.

Basically... just connect the
3.3v,
the Ground
and the TX of the NEO to the RX of the NANO.
At least, on my setup (red) Ublox Neo6m board wired to a NANO, it works (for what I want to do (GPS clock)).

If the NEO likes to have 3.3v and it gets 3.3v from a NANO, I do not see the reason why additional resistors should be added.

The NEO as it is only sending information via its TX to the RX pin of the NANO.

Further, if really resistors would be needed, Ublox would write it everywhere in big, fat letters... and they would probably have implanted these resistors or some sort of voltage control on their boards.

Do not forget that Ublox engineers have much more experience with their products than some of us around here. (I said "some of us"... this does not mean "all of us" !!!)

Input from anybody else is welcome...

[Squirrelbd]

If your controller's GPIO output is 5v during data communication, you should use a voltage divider to step down the voltage from 5v to 3v3. Sometimes without a voltage divider circuit, it works but is not recommended. Your module can burn in the long run.

Here is an example of the use of a voltage divider during serial communication between Arduino and ESP32.

You can follow this complete guide to interface and program the NEO-6M GPS module with Arduino, which is a detailed and in-depth guide with a video explanation.