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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24 views

How to get internet from Raspberry Pi 4 to my laptop? [closed]

Guys! I have Raspberry Pi 4 with GSM shield and want to provide internet for laptop. How to do this? Thanks!
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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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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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1answer
64 views

SIM868 powers down after few seconds

I designed a circuit with SIM868 module, and i followed the recommendation from datasheet to unsure suffusion current. The main power supply is getting from VCC:12V source converted to 5V by an DC-DC ...
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50 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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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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1answer
32 views

GSM DCE to TCP - mocking a GSM modem

I'm trying to interface a device (Opentherm thermostat) that actually supports to be controlled through SMS via a serial connection to a GSM modem. I'd like however to control it through TCP rather ...
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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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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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42 views

How to wire up GSM Modem(DCE) With MAX485

I am trying yo figure out how to directly connect a GSM modem (say SIM800) with a MAX485 . The purpose of this is to make an RS485 GSM Modem. I am struggling how to wire it up, do i wire the CTS of ...
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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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49 views

GSM Module + RS485 transceiver possible?

I was wondering if someone could confirm if it is feasible to interface a GSM module for example SIM900, SIM900, Quectel's M95 or Neoway's N10 , maybe if we use the RS232 interface with HW the flow ...
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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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263 views

SIM800 doesn't give GSM location

I have problem to get exact GSM location using SIM800L. I have followed instructions in the manual. But my module just gived me latitude = 0 and longitude = 0. This is what I do with my serial ...
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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

GSM SIM900 isn't communicating with the Arduino

When I connect my GSM SIM900 module to the Arduino and insert a SIM card, the Netlight and Status light blink for few seconds and then it stops. I am using 5V 1A to power the GSM and pins D7 and D8 ...
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443 views

What's this noise?

As in other years at precisely this time I'm experiencing an effect somewhat like GSM frame-rate audio breakthrough in my auditory systems - completely different frequencies but equally wideband. I've ...
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3answers
172 views

Can smaller trace width limit the current flowing through the PCB?

I am a computer science student and I am a newbie in electronics. I have designed a PCB for SIM800L, and I forgot to change the trace width of the copper rails. By default, the routing width was set ...
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1answer
40 views

Can a server send data to my SIM800c while it is in sleep mode?

I have a SIM800c and I'm also using an adafruit.io server. I'm building an alarm system and I'm wondering if I will be able to send commands to the system using the server while the GSM module is in ...
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33 views

Need help finding pin layout diagram for GSM module (SIM800c RPi development board)

I'm having a bit of a conundrum. I bought a SIM800c development board off of ebay but the pins are not labeled at all and I have no idea which pins Rx and Tx are. I really want to hook it up to my COM ...
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95 views

How does a GSM device (ME) decides which tower/base station (BTS) it should connect to

I'm looking for an article or specification that explains how a GSM device (ME) decides which tower/base stations (BTS) it should connect to. I'm looking for info specifically on the registration ...
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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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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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3answers
534 views

If a module is “arduino compatible”, does that necessarily mean it isn't compatible with other microcontrollers?

I'm trying to find a GSM module to pair with a PIC32 microcontroller for a project and I've found some nice ones. The one I'm really interested in is the SIM800C GSM module. Many of them say they are "...
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1answer
155 views

Are input filters always required for switching power supplies?

This is a follow up to the questions here and here I recently designed a PCB that contained a buck regulator (LM2576 5V). You can see the PCB layout in this question. After converting the input 12VDC ...
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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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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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368 views

stm32f107 uart frame and noise error

I made a device with a stm32f107 and sim800l gsm module . Module is in data mode(PPP) and I'm using LWIP library . My MCU clocks at 72MHz . My problem is that I get frame error and noise error when ...
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162 views

TCP data vs HTTP data over GSM modem

I am using M95 GSM Modem for remote data communication with the server. The server-end persons want me to use HTTP data connection. Another embedded guy has suggested to use sockets and TCP data for ...
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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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59 views

Long term health effects of a gsm modem [closed]

We all use internet through our mobile phones hence gsm infrastructure. I know the radiation exposure is higher than wifi. That's why I preffer wifi over mobile whereever i can. However I'm currently ...
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2answers
91 views

how to find GSM service level of a IP-connection?

I am using a GSM modem to send data to a remote server over TCP/IP connection. I am using STM32F103 for the software. I want to connect 3 LED's with the 'F103 to indicate which connectivity and ...
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2answers
53 views

Is there any active GSM antenna exist? [closed]

Active antenna amplifies received signals with active components, so it has better parameters. Active antenna for the only receiving systems like GPS and TV signals are exist on the shelves. But the ...
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1answer
116 views

JSON for GSM Comm on STM32

I am making a remote monitoring system using STM32F1 MCU in which there are few digital and analog sensors attached and I would send their readings to a remote server periodically. Can I use JSON ...
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1answer
78 views

Blocking code in Task of FreeRTOS

Today is my first day on FreeRTOS. I want to use it in STM32F103 for simple task handling as reading data from analog sensor and sending remotely using GSM module. I want to know what are the do's ...
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187 views

How do I correctly protect my MCU from resetting during a current surge on RF transmission?

I designed a PCB with a SIM868 module for data transmission. On the PCB, the MCU resets randomly on transmission start of the SIM module. On a breadboard setup, it worked just fine, even without caps. ...
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2answers
198 views

Mcu keeps reseting because of noise

I have a circuit in which there is a mcu lpc1768 and a gsm module sim800l. For power I use DC/DC converter and made a 4.2v using lm2576 for sim800l. Used that voltage, I made a 3.3v using ams1117 and ...
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178 views

SIM800C-DS power supply schematic

I have drawn a circuit diagram of a power supply for a SIM800C-DS IC from the datasheet but is it right or wrong? I am confused as it's my first time. I also want to know where to connect the ...
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2answers
171 views

Can I use the same antenna for GSM and RF433 MHz?

I've already designed a PCB with GSM/GPRS chip and also with RF 433MHz receiver only (without transmitter). I would like to know if I can use the same antenna for both GSM/GPRS module and RF 433MHz ...
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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
70 views

SIM800: AT-command to get connected sender ids

I want to roughly estimate where my Arduino currently is. For this, I want to fetch the identification numbers of the stations it is currently connected to, so I can put them into an API which then ...
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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
97 views

GSM Modem Transmission Issue

I'm having a problem getting this GSM modem to work with an FPGA (Spartan 3). I've already implemented UART transmission on the FPGA side,the MAX232 to convert TTL->RS232, and 3.3V->5V logic level ...
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1answer
144 views

Lithium thionyl chloride for GSM application

I'm trying o use a LiSoCl2 battery in a low power GSM application. When the system is in standby only the microcontroller(MSP430) is powered(3.3v) and the GSM(5v) and sensor(5v) is turned off. The ...
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1k views

Can't type on Virtual Terminal Proteus

I've connected my SIM900a module with PC via a USB to TTL converter. I'm using Proteus Virtual Terminal for check the AT commands. The problem is I can't type anything on the Virtual Terminal. Copy ...
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2answers
47 views

Cellular chip antenna feedline width?

I have a chip cellular antenna from Pulse W3544B. In the datasheet it is said to make the transmission line 1.34 mm thick which I feel is too huge and also I wanted to make a strip line for impedance ...

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