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Author Topic: Powering the GSM shield when not "shielded"  (Read 2503 times)
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Hi All,

I am currently using my GSM shield sat on top of a uno to send some data from a sensor to xivley. The shield starts up registers, connects, sends the data and then disconnects and shuts down. In order to save some power consumption I am moving away from the full UNO board and I have built a barebones atmega328 on a breadboard. For some reason when I try to power the shield via jump wires from the breadboard it can carry out a couple of connections to the server but it then hangs. This can then cause it to hang sporadicaly in a number of places, even when registering on to the network.

I assume this is a power issue and I am not getting the correct amps out to the board? As I say it can run fine from the uno via usb but not when powered in any other way externally. So what are you guys using? I have seen 4 AA's 8 AA's, capacitors in series etc but what is the most stable and typical usage?
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What gauge size is your jumper wires?
Not all wires can carry that much of current.
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Hmm maybe that is the issue. Currently have nothing to measure it with but heres a pic: https://www.dropbox.com/s/xczr68pxar7ylw7/2013-09-23%2017.33.30.jpg?m
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I was using something like that back then, it didn't work. That is around AWG28 I guess. Pretty thin wires.
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Hmm I'll have to see if I can find something a bit bigger then. Will the breadboard itself be a limiting factor also? Any recommendations on wire size?
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Ok switched to a better wire rated to about 2A but still no joy. I dont get how shielded and powered via usb the code and GSM runs perfectly not one crash.

Ive done the following setups:

1. Arduino and GSM shielded and running from USB = No crashes runs fine

2. Arduino and GSM not shielded but running via wires to pins. 5v to gsm Vin, 7 to Ctrl, Rst to Rst, 2 to TX, 3 to Rx, GND to GND. Uno powered by USB. Crashes at AT+CGREG everytime.

3. Arduino and GSM not shielded but running via wires to pins. 7 to Ctrl, Rst to Rst, 2 to TX, 3 to Rx. Uno powered by USB and GSM shield powered by 9v bat. Crashes at AT+QIACT everytime.


For clarification: Serial comms with the Uno dies whilst printing out the AT commands in debug mode. The GSM shield itself still flickers away and looks to be connected.

Here is a good output when running shielded:
Code:
AT%13%
63 72>AT%13%%13%%10%OK%13%%10%
AT+CGREG?%13%
72 103>AT+CGREG?%13%%13%%10%+CGREG: 0,2%13%%10%%13%%10%OK%13%%10%
AT+CGREG?%13%
103 6>AT+CGREG?%13%%13%%10%+CGREG: 0,2%13%%10%%13%%10%OK%13%%10%
AT+CGREG?%13%
6 37>AT+CGREG?%13%%13%%10%+CGREG: 0,2%13%%10%%13%%10%OK%13%%10%
AT+CGREG?%13%
37 68>AT+CGREG?%13%%13%%10%+CGREG: 0,1%13%%10%%13%%10%OK%13%%10%
AT+IFC=1,1%13%
68 85>AT+IFC=1,1%13%%13%%10%OK%13%%10%
AT+CMGF=1%13%
85 101>AT+CMGF=1%13%%13%%10%OK%13%%10%
AT+CLIP=1%13%
101 117>AT+CLIP=1%13%%13%%10%OK%13%%10%
ATE0%13%
117 0>ATE0%13%%13%%10%OK%13%%10%
AT+COLP=1%13%
0 6>%13%%10%OK%13%%10%
AT+CGATT=1%13%
6 12>%13%%10%OK%13%%10%
AT+QIFGCNT=0%13%
12 18>%13%%10%OK%13%%10%
AT+QICSGP=1,"giffgaff.com","giffgaff","password"%13%
18 24>%13%%10%OK%13%%10%
AT+QIMUX=0%13%
24 30>%13%%10%OK%13%%10%
AT+QIMODE=1%13%
30 36>%13%%10%OK%13%%10%
AT+QINDI=1%13%
36 42>%13%%10%OK%13%%10%
AT+QIREGAPP%13%
42 48>%13%%10%OK%13%%10%
AT+QIACT%13%
48 54>%13%%10%OK%13%%10%
AT+CGATT=0%13%
54 68>%13%%10%+PDP DEACT%13%%10%

54 74>%13%%10%+PDP DEACT%13%%10%%13%%10%OK%13%%10%

But when it crashes via 9v:
Code:
AT%13%
63 72>AT%13%%13%%10%OK%13%%10%
AT+CGREG?%13%
72 103>AT+CGREG?%13%%13%%10%+CGREG: 0,2%13%%10%%13%%10%OK%13%%10%
AT+CGREG?%13%
103 6>AT+CGREG?%13%%13%%10%+CGREG: 0,2%13%%10%%13%%10%OK%13%%10%
AT+CGREG?%13%
6 37>AT+CGREG?%13%%13%%10%+CGREG: 0,2%13%%10%%13%%10%OK%13%%10%
AT+CGREG?%13%
37 68>AT+CGREG?%13%%13%%10%+CGREG: 0,1%13%%10%%13%%10%OK%13%%10%
AT+IFC=1,1%13%
68 85>AT+IFC=1,1%13%%13%%10%OK%13%%10%
AT+CMGF=1%13%
85 101>AT+CMGF=1%13%%13%%10%OK%13%%10%
AT+CLIP=1%13%
101 117>AT+CLIP=1%13%%13%%10%OK%13%%10%
ATE0%13%
117 0>ATE0%13%%13%%10%OK%13%%10%
AT+COLP=1%13%
0 6>%13%%10%OK%13%%10%
AT+CGATT=1%13%
6 12>%13%%10%OK%13%%10%
AT+QIFGCNT=0%13%
12 18>%13%%10%OK%13%%10%
AT+QICSGP=1,"giffgaff.com","giffgaff","password"%13%
18 24>%13%%10%OK%13%%10%
AT+QIMUX=0%13%
24 30>%13%%10%OK%13%%10%
AT+QIMODE=1%13%
30 36>%13%%10%OK%13%%10%
AT+QINDI=1%13%
36 42>%13%%10%OK%13%%10%
AT+QIREGAPP%13%
42 48>%13%%10%OK%13%%10%
AT+QIACT%13%
« Last Edit: September 24, 2013, 02:44:52 pm by munkee » Logged

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It sure look like a power issue. Registering to the network will surely eat more current.
At least your 2nd setup should work. Probably some wiring mistake?

I doubt the 9V battery will do any good. Check the maximum current that can be delivered like for example the battery here: http://data.energizer.com/PDFs/522.pdf
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Thanks for the input. What type of ranges should I be looking for. Do I definitely need something rated upto 2A or would something slight lower suffice as I assume the big orange capacitor is on the board to deal with the spikes of high current required during reg?

I would ideally like to run off a lipo that I can then solar charge.

Actually just found this:

Quote
Power requirements
It is recommended that the board be powered with an external power supply that can provide between 700mA and 1000mA. Powering an Arduino and the GSM shield from a USB connection is not recommended, as USB cannot provide the required current for when the modem is in heavy use.
The modem can pull up to 2A of current at peak usage, which can occur during data transmission. This current is provided through the large orange capacitor on the board's surface.

So I guess the 700mA - 1000mA should be enough
« Last Edit: September 26, 2013, 01:50:19 am by munkee » Logged

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The design goal was to reduce the amount of current needed through the use of the huge capacitor.
Usually, the duration of 2A peak is in the us range but it is enough to cause a reset event. The capacitor tries to hold the voltage when this happens provided that the input current is not too low. I think the recommended 700-1000 mA should be enough.

When selecting battery, take a look at the maximum pulse current capability.
For example, I used a wrongly battery of Li Thionyl with 250 mA pulse current only.
The board didn't work and resets all the time. Then, I swapped to one rated for 2000 mA, then it work.
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Thanks for the info. I've gone for a solar charger since I will be using the whole setup un-attended for a while which is rated at 6000mAh with a 5v 2.1A output hopefully this does the trick!
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Have you solved the problem ??

My situation:

Atmega328 + shield powered by UsbSerial converter all works fine
Atmega328 + shield powered by 5v (2a) when the
Code:
gsmAccess.begin()
the atmega halt the sketch.

My connection :
GSM SHIELD | ATMEGA
+5v | +5v
GND | GND
Pin 2 | 4 (arduino 2)
Pin 3 | 5 (arduino 3)
Pin 7 | 13 (arduino 7)

Have you any idea ??

When  i compile the sketch:
Global variables use 1,710 bytes (83%) of dynamic memory, leaving 338 bytes for local variables. Maximum is 2,048 bytes.
Low memory available, stability problems may occur


* 2013-10-28 11.48.30.jpg (3003.08 KB, 2448x3264 - viewed 61 times.)
« Last Edit: October 30, 2013, 06:17:32 pm by ghennet » Logged

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