Developer Comment by Pat Hickey on March 6, 2009 at 12:27pm

The data pin on an arduino won't be able to output enough current to power the GPS. You need to use a linear regulator in order to power it from a battery, or a real 5V pin on a board you already have. Never depend on a data pin as a power source.

A capacitor of about 0.1uF is always a good idea, but your problem here is that the current protection circuitry inside the AVR is cutting the voltage on that pin.

Moderator Comment by Chris Anderson on March 6, 2009 at 4:15pm

Yes, just to confirm what Otto said, you can't power the GPS with the data pins. They're not designed to output any significant current, and you're bound to get glitches like you've seen (and possibly burn out the Atmega)

Comment by HugePanic on March 10, 2009 at 1:45pm

Hello gentlemen,

the problem seems to be different!

Whatever power source i choose, i still get these glitches (Even with a external battery).

Whenever the GPS´ TX pin is connected to serial-read-pin (pin0) of the arduino, i get these glitches.
I don´t get these glitches when i simply give 5v so the serial-read-pin.

Even if there is no GPS code (send/receive data) i get glitches...

When i disable all Serial funktion (means that i don´t call Serial.begin), the glitches are gone. --> i don´t think that there is a soldering problem for this....

It seems that the serial data of the GPS is disturbing so mutch, that it can´t read the receiver signals correctly.

I am reading the receiver data with Signal = pulseIn(pin, HIGH). That should be the correct way to do that... ??

I could filter the receiver signals to find and ignore the glitches, but that isn´t the way i wan´t it to be done.


Does anybody have a good/better idea how to solve this???

Moderator Comment by Chris Anderson on March 10, 2009 at 1:52pm

So, are you saying that when the GPS is plugged into ArduPilot's GPS connector and the ArduPilot board is powered the regular way and you're using the ArduPilot code, you get GPS glitches? Or are you using some other custom configuration of hardware and/or software?

We can only support you if you're using the recommended configuration--it's too hard for us to diagnose hardware and software combinations that we've never seen or used.

Comment by HugePanic on March 10, 2009 at 2:15pm

I am NOT using a ArduPilot.
I am using a Arduino dicemilla. The EM-406a GPS module is connected to the Serial pins.

Moderator Comment by Chris Anderson on March 10, 2009 at 2:27pm

Oh. I'm afraid I can't help--we're only supporting ArduPilot. Maybe someone else here has some suggestions?

Out of curiosity, why aren't you using ArduPilot? It's cheaper than a diecimila and makes all the stuff you want to do very easy. Smaller, lighter, etc.

Comment by HugePanic on March 10, 2009 at 3:02pm

Ardupilot is my fall back solution!

But it's about loosing the battle when i switch to a bought system that runs pretty much out of the box now.

My idea is DIY, and i don't want to stop just because of that problem.

By the way: Did you analyse the signals you can read with the ardupilot? My glitches are about 10-20% of the signal, so if you only switch channes (digital) you wouldn't notice them...

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