GPS datalogging shield issue

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gillerire
 
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GPS datalogging shield issue

Post by gillerire »

Hi everybody,

I'm having an issue with the GPS datalogging shield. I have soldered it all together and uploaded the standard logging sketch without a problem, but when I turn it on it logs for a few minutes and then seems to die.

I'm using the EM-406A GPS module. When I plug in power the GPS LED comes on to signify that it is searching for satellites. Then it begins to flash once it gets a lock, and so does the green LED on the shield to show that it has started logging (the red LED on the shield also lights up). After a few minutes both LEDs on the shield switch off and the LED on the GPS module becomes very dim and blinks randomly.

If I open the file on the SD card, it has data recorded for the few minutes while it was working and nothing else.

Anybody have any ideas?

PS - I'm in Australia if that makes any difference.

jdl2001
 
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Re: GPS datalogging shield issue

Post by jdl2001 »

Are you running off wall power or batteries? Does the Arduino also die or go dim? If it's not weak batteries and the Arduino is still glowing brightly, make sure the power solder joint for the GPS is solid. Other than that, I'm at a loss. Frustrating I'm sure.

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gillerire
 
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Re: GPS datalogging shield issue

Post by gillerire »

Thanks for your help :)

It is running off a 9V battery. I also thought it might be a power issue so bought a brand new battery but got the same result.

I'll check what the Arduino does when I get home tonight, and also have a look over the solder joints.

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adafruit_support_bill
 
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Re: GPS datalogging shield issue

Post by adafruit_support_bill »

That would be consistent with a fading battery, but if a new cell does the same thing, you probably have a different problem.
If you post photos of the front & back of the board we'll have a look for any assembly issues.

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gillerire
 
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Re: GPS datalogging shield issue

Post by gillerire »

Ok, I have done a few more tests:

When using a 9V battery the Ardunio does indeed go crazy when the GPS/shield goes crazy.

I plugged it into wall power and had no problems at all.

Seems to indicate that it is an issue with power when attached to the battery. Is 9V too small?

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adafruit_support_bill
 
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Re: GPS datalogging shield issue

Post by adafruit_support_bill »

9v batteries are only suitable for relatively low-drain applications. They have a fairly high internal resistance and low power density. An Arduino with a couple blinking leds will run on one for quite a while, but both the GPS and the SD card are significant loads and will drain it quickly.

If you need the portability of battery power, a good alternative is the 6xAA holder: http://www.adafruit.com/products/248
rechargeable 7.2v packs are also readily available and work well.

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gillerire
 
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Re: GPS datalogging shield issue

Post by gillerire »

Well, I guess that's problem solved then :)

I'll go find myself a 6xAA battery holder.

Thanks for your help.

jsluke
 
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Re: GPS datalogging shield issue

Post by jsluke »

I use a 9V battery to power my GPS Logger and I have additional sensors. With a standard 100mA/h battery I get just over 1 hour of battery life. I recently bought a pack of 500mA/h batteries and can get over 4 hours of logging with a 9V battery. If your battery is draining that quickly I'd still suspect some form of wiring problem.

One thing I noticed is that battery life is much shorter when the GPS is first powered up. I don't know if this is the case but it seems to me that when the GPS is acquiring its position for the first time it uses more power. Perhaps a GPS specialist can advise if that's true (it's pure observation on my part with no formal measurement).

Either way, a 9V battery should give you more than a few minutes.

James.

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gillerire
 
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Re: GPS datalogging shield issue

Post by gillerire »

The plot thickens!

I'll have another look and see what I can suss out. Maybe I'll hook my meter up to the battery and see if the voltage drops significantly when it is acquiring satellites.

I'll also have another look over my soldering.

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