Questions tagged [gsm]

GSM stands for Groupe Spécial Mobile. It is a standard set developed by the European Telecommunications Standards Institute (ETSI) to describe protocols for second generation (2G) digital cellular networks used by mobile phones.

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106 views

Running Application on SIM808 GNSS module beside it's internal firmware

I'm trying to load my written program to SIM808 and the module will be responsible for running my program and also its internal firmware. SIMCOM has a document about doing this in SIM800 module but ...
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324 views

Understanding EGSM-900 (LTE 8 band) electromagnetic spectrum

I am trying to fully understand the physical layer of the GSM standard. For doing that I am looking at the E-GSM-900 band (mostly used in Europe). In my country these frequencies has been assigned to ...
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197 views

GSM noise from a 2-layer PCB with SIM800C

I've designed a 2-layer PCB that contains a 12-5V buck converter (P2576L-50 - a Clone of the LM2576), 3.3 (AP1117-33) and 4V (MIC29302WU) shunt regulators, an STM32 micro and a SIM800C GSM module. ...
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1answer
795 views

Interfacing SIM900A GSM Modem with TM4C123G TI microcontroller

I was hoping you guys could help me on connecting SIM900A GSM Modem with this TM4C123 micro controller. I connected the RS232 ports of TX, RX, GND and power ports to GND and +12V. should I connect ...
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166 views

GSM interference on an wireless micrphone

I am getting GSM Buzz on a wireless micrphone system. The interference is coming from the Micrphone itself as it is transmitting it in the audio and is not being caused by direct RF interference with ...
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496 views

Isolation between GSM and GPS antenna

We are doing a prototype for a gps based tracker. We got a problem in placing the GSM and GPS antenna. Both the GSM and GPS antenna are omni-directional antennas. In forums and application notes, the ...
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45 views

SIM800L microphone problem

I want to feed SIM800L a microphone signal. I found this page in the datasheet and it worked but I need more a sensitive microphone. I want to hear voices in room as much as possible, like a spy bug. ...
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30 views

How to put Sim808 and a microcontroller on the same PCB?

I'm families with Arduino (Nano and mini) and GSM modules and I've recently Learn about Altium Designer and I've designed (and ordered) a few simple PCBs and I've learned about Micro controller and ...
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49 views

How to prevent noise when connecting “speaker out” of SIM800L to audio mixer?

Aim I'm trying to build a device to be used for call center agents. They could make calls via this device, which could be connected to a PC to be able to record this conversation. Solution Build ...
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49 views

Smartwatch GSM antenna design

Which antenna design is the most applicable to a 2G smartwatch (about 40x40mm)? I have tried some sketchy ultra-short (about λ/8) whip antennas, but due to a fairly small ground plane and unfortunate ...
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1answer
143 views

GSM antenna CPW design

I'm designing a board with a GSM modem, and the plan is to hook this up to an SMA connector and thence to an external antenna which will live outside the metal enclosure. I'm aware of the need to ...
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652 views

SIM800l power-up problems

The datasheet of the SIM800l claims that currents can peak to around 2A during SIM registration and other network intensive activities. I tried powering up the module with the 5v output of a FTDI-USB ...
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238 views

LTE vs 3G power cost at low speed

I am currently working on a device in which I need to implement internet connection. For that I intend to use a GSM module, for example this one: SIM5320. This is a 3G module. I have been reading ...
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2k views

Cannot send SMS with SIM900 GSM module

I have a little problem using GSM SIM900 module connected to the Arduino the call is working alright but it doesn't send me SMS I don't know why. This is my code: ...
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613 views

SIM cards not responding to SIM908 module

I have a SIM908 module on a dev kit board. I have three SIM cards that are all detected fine on the previous version of the board. However, the v2 only detects one out of the three SIMs. I put the ...
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2answers
312 views

STM32F4 and SIM800L logic level

I am currently using an STM32F401RE that I have to interface with a SIM800L GSM module via UART. In a first "toy example" I used Arduino and found no problems, but passing to the STM MCU I am unable ...
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15 views

SIM800L CREG AT command returns 0,2 when no SIM and 0,0 when SIM is inserted

I have an SIM800L module. It is connected up in the same way as this website shows,( i.e 10K resistor from Rx to Arduino data-pin and 20K resistor from Rx to ground.) Only difference is I'm using an ...
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11 views

USB Modem design for GSM Power Supply

I want to run GSM module with Laptop Power through USB. While searching, I have found one document. In the document it is mentioned that five 150uF capacitor need to be used for energy conversion. ...
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41 views

SIM800L Auto Connect..!

I want to know does the SIM800L module connect to the network automatically without any user commands? Because some modules will disconnect in low signal areas & some SIMs will be disconnected by ...
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13 views

Interfacing RN52 with SIM800C

I am interfacing an RN52 with SIM800C to make calls to and from the bluetooth device and so i have connected the speaker line of SIM800C to the mic of RN52 and the mic of SIM800C to the speaker of ...
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38 views

HSE STM32 crashes during GSM operation

Faced with such a problem. CSS (clock security system) is enabled for the STM32F205RET6, when an HSE fails, an NMI interrupt is generated. I register the failure fact in BKPSRAM STM32 and do a reset. ...
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18 views

SIM800l Replies with a delay. Http Get

I trying to use http get method on SIM800l (mcu for controling SIM800 is STM32F407VGT6). I can send SMS message or read all/specific SMS message but with http methods I'm in trouble(power supply is ...
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39 views

sim900a not responding?

I'm using the sim900A module to try interface with mega 2560 controller using serial1 send SMS to my mobile but it will respond nothing, below I have attached a picture of the gsm module and code ...
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31 views

How to control microphone-speaker connection between two SIM800Ls with a GPIO terminal?

There is a device consisting of two SimCom SIM800L quad-band GSM/GPRS modules and controlled by an MCU, presumably ESP8266. The idea is to let the first SIM800L call one person, the second SIM800L ...
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42 views

Can I directly connect microphone to speaker of two SIM800Ls

There are two SimCom SIM800L quad-band GSM/GPRS modules. I would like to make some kind of call relay, such that SIM #1 accepts incoming call, then SIM #2 executes outgoing call, and once both ...
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53 views

GSM Antenna - SIM800L

I want a 90 degree rotate antenna for my SIM800L module.I couldn't find one so I hooked up a wifi antenna & it worked nicely.Does it matter for reliability? Does it match with my sim800L module? ...
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33 views

SIM868 breakout board does not accept GNSS/GPS AT commands

I bought SIM868 breakout board with GNSS support. https://www.aliexpress.com/item/33013782111.html However, I can’t get coordinates using standard at-command AT+CGNSPWR=1, AT+CGNSTST=1, etc. I get “+...
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64 views

sim800 - TCP GPRS slow socket opening

I'm trying to create an internet interface for my AVR project using a SIM800 module, which I use to open a socket to my server. My only problem is that bringing up TCP takes lots of time. The other ...
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1answer
34 views

Telit cellular module pins connection

I have the UE910 cellular module from Telit. I have manufactured a PCB containing the module but it's not working (power is reaching it but serial program not communicating with the tx and rx pins). I ...
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1answer
178 views

SIM800L Disconnecting Issue

I'm doing a project using SIM800L ebay module.I can send & receive SMS & calls. The problem is, on workbench its working, but in actual site environment when the GSM signal is low & it ...
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1answer
65 views

Power supply design with charging circuit

I am designing a GSM modem power supply circuit. The circuit requires a 2A power supply. The module SIM800C itself can be powered directly by Li-Ion or Li-Poly battery power. I am looking at a ...
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208 views

How does GSM Module store incoming SMS in its “SM” or “ME” memory?

I am using AI Thinker A7 GSM/GPRS/GPS Module demo v7.1.(The Rx, TX, GND pins of this module are connected to tx, rx, gnd pins of the prolific Rs232-TTL converter and a virtual com port is open in ...
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143 views

GSM antenna connection from the phone does not make sense

I recently came across a phone (Samsung Galaxy Grand Prime SM-G530f) with trouble getting any network signal, I did some troubleshooting and ended up finding out that one of the pin(the GSM pin) to ...
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1k views

SIM800C - CME ERROR: 15 SIM wrong & CME ERROR: 10 SIM not inserted

I am making a GSM Tracker with SIM800C module. After deploying it into vehicles.. It works fine.. but after some days, it starts responding as CME ERROR: 15 SIM wrong for command AT+CPIN? & CME ...
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1k views

IP over LwIP PPPoS with Telit GSM GL865 and STM32F7

I am using Telit GL865 GSM Modem with STM32F7 nucleo development board. I make them communicate via USART1. Firstly, I configure the modem with AT commands as below; after that, modem starts to send ...
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822 views

Enabling SD card access on SIM808

I am currently working with SIMCom's SIM808 2G+GPS modem. In my setup, an MCU communicates with the modem over UART to save some data in the SIM808's filesystem. As the modem's built-in memory is < ...
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1answer
203 views

Can the M590E's boot pin be used to reduce power consumption?

What does the boot pin actually do? Can it be used to reduce the module's power consumption when the module is not required? All recommendations are to pull it low to boot. Can it go hi again to turn ...
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268 views

In-rush current limit MOSFET, resistor

I'm using DC/DC converter LTC3112 to supply GSM module. Battery source is about 12V and DC/DC output is 3.7V. Microcontroller logic is 3.3V powered from other DC/DC converter. The application is ...
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1answer
630 views

Usage of car burglar alarm system to send sms with GSM unit and arduino

My vehicle have a car burglar alarm system. I want to setup Arduino Nano or Micro Module with SIM800L GPRS GSM Module to get SMS when alarm raised. I want to clarify these things. I think easiest ...