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arbitrary shutdown of GM862-GPS - SparkFun Electronics

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Tips and questions relating to the GPS modules from SFE
By Gauner
#36828
I have the module on the Sparkfun $29.95 breakout board connected to the PC serial port via MAX2323.
Everything is fine, i can send and receive commands to the module.

But as soon as ist connects or tries to connect to a GSM-network, the modules shuts down itself.
So, everything is cool, until i put in a SIM card and enter the PIN.
Or, if i unplug the antenna, I can reach the simcard, the module stays on, because it gets no network.
But, as soon as unlocked SIM AND antenna is connected, so the module could connect to a network unhindered - arbitrary self-switchoff. :-(

Current firmware version is 07.02.403
I already changed to a former firmware 07.02.402 - same problem.

Has anyone experienced this behavior as well?
How can I be helped?
Last edited by Gauner on Fri May 14, 2010 4:04 am, edited 1 time in total.
User avatar
By leon_heller
#36829
Can your supply deliver enough current to meet the peak requirement when transmitting?

Leon
By Gauner
#36830
Yes, very sure. I have a precision DC Power supply. The module pulls 10mA current, and the current limit of the supply (2A) doesn't take effect yet. It is way under the limit.

What else can it be?
By busonerd
#36835
Gauner - when you transmit, your power will burst much higher than 10ma - up to 2 A, or greater,

Cheers,

--David Carne
By Gauner
#36836
Hmm, I have my supply limit set to 2.5 A, and: I have a LED on it, which lights up, if the current limit gets active - in this case it doesn't, really!
The current doesn't go up!
I think i know why: ;-) Because the module doesn't connect to a network. it prefers to switch itself off.
Obviously before even connecting, because it happens before the current goes up.
But, really sure sure sure, the current is not limited below 2.5 A, and the voltage is stabilized like a charm to 3.8 V.
By Gauner
#36837
Is there a chance to get any debug output from it, to see what it does and what happens inside?
Do You think I got a corrupt module?
By busonerd
#36850
I doubt the module is corrupt - do you have any capacitance near the power supply to the module? If not, you might want to add some, especially if you have a cable run to the power supply.

I highly suspect its a power supply issue. The symptoms you describe are identical to ones we've dealt with many times before, which is the module turning on its RF section, and then browning out, and shutting down.

Cheers,

--David Carne
By Gauner
#36893
Oh yes, that was it! Having read Your posting I tried a bigger capacitor - now it works! I had a too small one.

Thank You very very much!
By Anadian
#40530
Hello,

I also have problems with Telit GM862-GPS modules.

I have 6 of them.

They shuts down themselfs regulary after 3-4 days.
Within this period they are working just fine, but after that I found them in power off mode (status LED stops blinking),
like when they are turned OFF with on/off button.
If the modules are again turned on via on/off button, they continue to work without any problems,
but after 3-4 days they again shuts down themselfs ...


Does anyone had similar problem, or have any idea what is going on ?


I am pretty shure that there are no problems with power supply.

It is stabilised at 3.89 V, and capable of 2.5 A continuous current draw.
As of capacitors, there are 2 x 100 uF/10V low ESR tantalum capacitors very close to the module and are bypassed with 22nF ceramic cap.,
also there are 2 x 1000uF/6.3V Panasonic capacitors that are also very close to the module and L5973D
voltage regulator (which runs very cold), PCB power supply tracks are wide and short, power supply wires are also short and of heavy gauge,
so there are no problems with voltage drops.
Also, module metal case pins are soldered to PCB groundplane - GND.
Everything runs at room temperature, and there are no any noticable heat dissipations ...

Please, anyone have an idea why modules are powering down themselfs after 3-4 days of operation ??


Best regards,
Anadian K.
User avatar
By leon_heller
#40532
A voltage transient from the mains supply?

Leon
By Anadian
#44895
Hi,

Thanks Leon.

But modules don't runs from mains, they all are installed in the cars, they run from car batteries.

They shuts down themselfs regulary after a few days of perfect operation.

Anyone have a clue what else could be a problem ?

Best regards,
Anadian K.
User avatar
By leon_heller
#44897
It could be a transient from the car supply, then. Have you got any transient protection, like an AVX TransGuard, on the regulated supply input?

Leon
By noceco33
#45604
Gauner wrote:As soon as ist connects or tries to connect to a GSM-network, the modules shuts down itself.
So, everything is cool, until i put in a SIM card and enter the PIN.
Or, if i unplug the antenna, I can reach the simcard, the module stays on, because it gets no network.
But, as soon as unlocked SIM AND antenna is connected, so the module could connect to a network unhindered - arbitrary self-switchoff. :-(
I have the same problem, But I dont know what is the current wich I feeding my device (I´m not in the lab now, and is my fist day with GM862).

I´m ussing Arduino, and the supply is via USB cable, as the data. So tomorrow I going to check that. I need 2mAmp??
And if that is not the problem, can you (Gauner, Busonerd or someone) explain me th capacitors stuff??

By the way I don´t think that is gonna be the problem, cos my university bought me a builded board from a company, so I suposed that that company check the capacitors!!

Thanks
User avatar
By leon_heller
#45605
You must have a 100 uF low-ESR 100 uF capacitor like a tantalum directly across the GM-862 supply pins. It's in the hardware manual.

Leon
By jvd
#78588
Sorry for bringing this up again, but has anyone tried a low-esr aluminum electrolytic capacitor (I'm thinking Panasonic FM). (through-hole = easier to prototype). I'd go for 6800 uF to keep the current drain lower . Just not sure if there is a reason this wouldn't work?