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Topic: Cheap GSM module (SIM800) not connecting to the network (Read 142042 times) previous topic - next topic

juan3211

Hi, an experiencie of 10 minutes: a Li-Ion battery to power SIM800L (4.2V) and a Arduino board compatible with 3.3V power, so RX and TX with 3.3V logic.

With this config I hasn't got any problems in that 10 minutes.

Regards

jule

Hi, does anybody solved the topic title problem?

Im using a SIM800L module. (Iv tried a second SIM800L but the second module is doing the same)
and
..a laboratory power supply with 3AMPS and tried 3.8V up to 4.4V -> everything OK.
..an FTDI adapter with 3.3V TTL TX RX signals -> SIM800L communicates well with PC.
..Arduino with TTL 5V to TTL 3.3V curcuit. -> Module communicates well.

Im using two different provider SIM cards. DREI and YESSS (both from Austria -> Im from Austria :)
With DREI SIM card (1 Year old - for 3G and 4G) it is registering in network automatically
with AT+CSQ it says +CSQ: 30,0 - and with AT+COPS=? it shows the available providers and marks the correct provider with 2 (means than it has registered to this network) -> ->
-> so everything seems OK
BUT it does not send SMS every try. (Im doing it right because it worked two times from tens of tries).

Question: A timing problem? Must the commands be sent to the module in an exact time?


Now the proper Problem!
With YESS SIM card (brandnew prepaid card for 3G and 4G) it registers neither automatically nor manual.
AT+CSQ always says +CSQ: 0,0 (means no signal ?!)
And AT+COPS=? shows the available providers and marks the correct providers with 1 (means the providers are matching). AT+CREG? shows +CREG: 0,2 (2 proper providers available)

It always shows the messages:
+CFUN=1
+CPIN: Ready
Call Ready
SMS Ready

Question: Has anybody found out why it is doing this? Does a SIM900L doing it better?

Thank you so much
Juergen

navaljosh

Hi,

I am having the same issue. AT+COPS=? returns multiple carriers, but AT+COPS? returns 0. What should i do?

merolicos

#48
Jan 20, 2017, 07:29 am Last Edit: Jan 20, 2017, 07:35 am by merolicos Reason: THIS IS MINE
I found the issue.

you have to add ";" at the end of the string
ex: ATD667755332211;

First the usb port current is enough for the sim808 (around 500ma) but less than you'll get "UNDER VOLTAGE WARNING".
The arduino voltage is enough (but high) and the current as well.

Most of the sim cards are supported by the sim808 even 4G.

If you can send sms and receive calls you need a semicolon.

Please check this log:

AT
OK

(NO NEED IT A SIM PASSWORD)
AT+CPIN?

+CPIN: READY

OK

(IF WAS SUCCESSFUL REGISTERED ON THE NETWORK)
AT+COPS?

+COPS: 0,0,"SOMETEXTHERE"

OK

(QUALITY SIGNAL, DON'T EXPECT MUCH WITH MORE THAN 11)
AT+CSQ

+CSQ: 10,0

OK

(FINALLY THE CALL :)
ATD123456789;

OK



pronoob72

I have bought a SIM800L eval board (ebay). I had the same issue as many describe. I could write and read commands and get it running stating
Call Ready
SMS Ready
But it never connected.

But I noticed that I could repeat doing "AT-CPIN="xxxx"" and then it would state again
Call Ready
SMS Ready

Seems like it reset immediately after this

The issue was that the Arduino board did not supply the necessary 2A to the SIM800L. I connected the sim800L (my sim800L has local regulator) to another source that could supply 2A and then it stayed on!

Now I can receive calls, send&receive sms etc.

hashir135


Hello guys

i have bought a cheap SIM800 gsm shield

https://www.aliexpress.com/item-img/SIM800-GSM-GPRS-module-STM32-SIM900A-Upgrade-board-GPS-module-C1A3/32692980971.html?spm=2114.10010108.1000017.1.dzzinm

When i press PWR_KEY the NET_STA led quickly blinks 3, 4times and then it is off.
No AT commands are working

anyone help please

hashir135

got it. the input voltage to the sim800 was less then the rated. it was around 3.5V and when pwr_key pressed it even goes down. used 4v and everything worked fine

john_anderton

#52
Mar 10, 2017, 10:05 am Last Edit: Mar 11, 2017, 05:54 pm by john_anderton
Problem solved for me. This is how
My problem was similar ;

AT COPS return 1 but cannot auto register to the network

the solution was simple but it took me two days to find out

I just AT+CBAND?

the response was +CBAND: EGSM_MODE

after that I typed

AT+CBAND=?

 the response was

+CBAND: (EGSM_MODE,DCS_MODE,GSM850_MODE,PCS_MODE,EGSM_DCS_MODE,GSM850_PCS_MODE,EGSM_PCS_MODE,ALL_BAND)


For me the mode that worked is "DCS_MODE" and after I typed

AT+CBAND="DCS_MODE"


the modem connected automatically and now it is fully functional


 





NickF93

I've just bought SIM800L.
When I use the command AT+CPIN? it reply with "SIM not inserted" (but SIM is in). Why?  :smiley-confuse:

najab

GSM SIM 800L: GPRS connection lost how it works fine? any idea please help me
it get ip 0.0.0.0

AT+SAPBR=3,1,Contype,GPRS
OK
AT+SAPBR=1,1
ERROR
END
Start
AT+SAPBR=2,1
+SAPBR: 1,3,"0.0.0.0"

gmora30

Hello, greetings from Venezuela.

I had the same problem, SIM800L has not connection to the operator network, Movistar in my case.

Then of change band mode with AT command: AT+CBAND="GSM850_PCS_MODE", the modem it registered inmediatly to ther network.

Then of 3 days of continuos research and work this was the magic solution, no source power, no circuitery aditional, no more nothing. Only this small change.

I hope this can be help you.

Bye!

Kingside

Hi everybody.
Many troubles and many good answer here. Lets make a conclussion.
I talk about the SIM800L which I want to connect to an Arduino Nano or Arduino Uno for example. The other modules are very similar

1. Connection.
Theoretical part:

Voltage/Currency:
- The Module needs 3,8V-4,3V. Some people recommend 4,2V. And 2A Currency, when it will send over GPRS. We can not use the Power of Arduino because USB give us only max. 500mA.
- The Arduino needs 5V. This is the reason why we must have 2 seperate power lines.

GND: But the Ground must be connected to each other.

RX/TX: This is very easy. RX from Sim800 goes to TX from Arduino and TX from Sim800 goes to RX from Arduino.


Ok. For now we have a connection like that:


The Problem begins now:
Some people said that we must have a diode between TX Sim800 and RX Arduino.
Others say, there must be a 10k Resistor.
Also another combine:


Or divide the voltage of the RX from Sim800 to 2.8V:


Onother way of this Thread:

Many ways to came to rome or which way is correct?






geologic

The Problem begins now:
Some people said that we must have a diode between TX Sim800 and RX Arduino.
Others say, there must be a 10k Resistor.


Or divide the voltage of the RX from Sim800 to 2.8V:


Many ways to came to rome or which way is correct?


They are all correct... Rx line (connected to arduino) will see 5V, if you power SIM800 with 4V, there is a extra 1V on that pin. So to be safe, use a voltage divider, a level shifter or whatever to lower that pin to 4V max.

If you connect RX pin directly, it can do no harm, or it can fry your module... 2 resistors cost 0,1$... why do you want to take a chance? how much cost a dead SIM800 module?


 

Kingside


geologic

Don't use a voltage divider to feed 4V to SIM800... As soon it tries to get mA from it, voltage will drop. Use a LDO with a nice input cap. I use MCP1826 with a 470uF input cap (besides input and output recomended cap).

But you can feed 12V jack directly to arduino and use the step-down module regulated to 4V to feed SIM800 module...

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