Adafruit Industries, Essential service and business: NYC – Executive Order 202.6 - Read more.
0

Adafruit FONA 3G Spontaneously Resetting
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Adafruit FONA 3G Spontaneously Resetting

by akoz on Mon Mar 23, 2020 9:48 pm

Hello,

I just soldered the bias jumper on an "Adafruit FONA 3G Cellular + GPS Breakout" board, as recommended to enable use of an active GPS antenna (the GPS wasn't getting a lock before) but the board now behaves as if it's spontaneously resetting.

IMG_E8546 edited.jpg
IMG_E8546 edited.jpg (179.55 KiB) Viewed 73 times


Circled in green is the jumper I soldered, and in red are the lights that are cycling on and off. The timings are about 7 seconds on, 15 seconds off. I have a lithium battery connected, but its absence doesn't affect this issue.

The on period coincides with being able to connect to a Windows computer via USB, and I can even establish a serial terminal connection through the "AT Port 9000" device if I'm very quick. The connection is lost when the lights go out.

Does anyone know anything about this phenomenon?

akoz
 
Posts: 6
Joined: Mon Mar 23, 2020 9:09 pm

Re: Adafruit FONA 3G Spontaneously Resetting

by adafruit_support_mike on Tue Mar 24, 2020 5:09 am

As a sanity check, does the behavior stop if you disconnect the antenna? It's possible than an active antenna might be shorted or causing some kind of power drain. Disconnecting the antenna should remove any such load though.

adafruit_support_mike
 
Posts: 61014
Joined: Thu Feb 11, 2010 2:51 pm

Re: Adafruit FONA 3G Spontaneously Resetting

by akoz on Tue Mar 24, 2020 12:42 pm

It still happens even when I have nothing connected to the antenna port. I even removed the little UFL-SMA cable that the active antenna plugs into, so that the GPS antenna port on the board is bare.

I just noticed something else. The timings are not constant. The "on time" is consistent at about 7 seconds, but the "off time" rises from 6 seconds to 13 seconds after being plugged in for two minutes.

I'll leave it alone for a few hours, and see what changes.

akoz
 
Posts: 6
Joined: Mon Mar 23, 2020 9:09 pm

Re: Adafruit FONA 3G Spontaneously Resetting

by akoz on Tue Mar 24, 2020 10:27 pm

Not much change. If the battery is connected, the "on periods" remain roughly constant at about seven seconds, and the off periods get longer and longer until they reach about twenty seconds.

With the battery disconnected, the on periods remain unchanged and the off periods drop to 4 to 4.5 seconds.

I'm baffled. If the forum has no suggestions, I'll try to unsolder that jumper, in the hope that I can make the board useful for cellular comms.

akoz
 
Posts: 6
Joined: Mon Mar 23, 2020 9:09 pm

Re: Adafruit FONA 3G Spontaneously Resetting

by adafruit_support_mike on Wed Mar 25, 2020 3:56 am

The FONA will definitely reset if the LiPo isn't connected.

The radio uses burst current of up to 2A, and the only traces on the FONA that can carry that much power are the ones from the LiPo. Without a properly charged LiPo, the radio will basically short circuit the power supply until the voltage falls low enough to make the board reset.

Try using a different LiPo and see if that has any effect. I can't tell for sure in the photos above, but it looks like the yellow and green LEDs near the LiPo jack might be lit, which indicates a battery problem.

adafruit_support_mike
 
Posts: 61014
Joined: Thu Feb 11, 2010 2:51 pm

Re: Adafruit FONA 3G Spontaneously Resetting

by akoz on Wed Mar 25, 2020 2:18 pm

I have no other LiPo battery, but the board was working properly for serial connection and cellular text messaging before I soldered that jumper.

(Some context: this is for a college project, and I'm having equipment access problems because of the Coronavirus-related shut down. I may have to open that jumper without using solder wick.)

I've never seen the green LED near the LiPo jack light up. I've only ever seen the yellow, and it lights up whether or not the battery is connected.

How long should the battery take to charge, and does it matter for charging if the FONA is connected via USB to a computer or to an external 5V battery pack? The LiPo is a GSP 585460, 2000mAh, 3.7V.

akoz
 
Posts: 6
Joined: Mon Mar 23, 2020 9:09 pm

Re: Adafruit FONA 3G Spontaneously Resetting

by akoz on Wed Mar 25, 2020 2:33 pm

The battery's output connector (where it plugs into the FONA's LiPo jack) reads 2.7V unloaded. That's in spite of the LiPo being plugged in and, I thought, charging for several hours yesterday.

The LiPo read as charging last week, before I soldered the jumper, when we were commanding the FONA with an arduino and checking the battery state with a software command.

Is it possible that the FONA is drawing much more power with the jumper closed, even though there's no GPS antenna connected, and that the battery is unable to supply that extra power for some reason?

akoz
 
Posts: 6
Joined: Mon Mar 23, 2020 9:09 pm

Re: Adafruit FONA 3G Spontaneously Resetting

by akoz on Sat Mar 28, 2020 2:21 pm

Desoldering the bias jumper made no difference to the board's behavior. Removing the SIM card extended the length of the board's "on time", but it still cycles on and off even after sitting that way for hours.

Is there a way of testing the LiPo independently of the board, or of charging it by some method other than using the board?

akoz
 
Posts: 6
Joined: Mon Mar 23, 2020 9:09 pm

Re: Adafruit FONA 3G Spontaneously Resetting

by adafruit_support_mike on Sun Mar 29, 2020 2:57 am

What voltage do you see between the LiPo's positive and negative leads?

You can connect the LiPo to any other charger that's designed to work with cells whose full-charge voltage is 4.2V. The FONA has one built in, but you can use others.

adafruit_support_mike
 
Posts: 61014
Joined: Thu Feb 11, 2010 2:51 pm

Please be positive and constructive with your questions and comments.