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9 votes
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Difference between SoftwareSerial and Serial

All Atmel MCU, on which Arduino models are based, include special hardware for serial communication; this part of the MCU is called USART (stands for Universal Synchronous/Asynchronous Receiver/...
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6 votes

Arduino Mega + SIM808 GSM + GPS Module + Program Switch ON without pressing Push Button?

There is a simple way of power the module without pressing the button. There is pin call D9 at the bottom right corner of the module. Just power the pin by Arduino digital pin or 5v pin around 3, 4 ...
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6 votes
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Which pins of an Arduino UNO can be used as Tx and Rx pins for connecting to GSM GPRS SIM 900A

The best choice for serial communications is obviously the HardwareSerial object, Serial, on pins 0 & 1. However, it is really dedicated to the USB connection (via the onboard Serial-to-USB ...
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  • 1,984
5 votes
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Connecting a Arduino to FT232

Unfortunately, no, as the FT232 would have to act as a USB host device. A USB host shield might work if someone has written driver code to support 3G modems.
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  • 2,886
5 votes
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SerialGSM for GSM shield without SoftwareSerial

SerialGSM is designed to work with software serial, as you can see that from the class declaration in the SerialGSM.h header: class SerialGSM : public SoftwareSerial { ... }; Unfortunately, changing ...
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4 votes
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Receiving SMS by Arduino GSM Shield and control the LED with the content of this SMS?

First of all, you have a typo: You need the double-equals operator in if (c == 'off') { But more importantly, you can't use a char variable to hold or compare more than one character at a time. I ...
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4 votes
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How to communicate the Arduino board with SIM900?

I'll tell you what worked for me, because I didn't find the schematics of this board. But your board may work differently, so it is always good to check the datasheet and the schematic (if you have ...
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  • 242
4 votes

Cheapest Arduino GPRS or 3G solution

If you are finding Cheapest and working module you can you SIM800L less then 4$. aliexpress.com/item/Free-Shipping-Smallest-SIM800L-GPRS-GSM-Module-MicroSIM-Card-Core-BOard-Quad-band-TTL-Serial-Port/...
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4 votes

MQTT client on Arduino + SIM900

MQTT Library for SIM800 GSM Modem is available at ElementzTechBlog, ElementzGithubRepository Functionalities: Auto connect Automatically connect to TCP and to MQTT server. connect function This ...
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4 votes

SIM808 module GSM working fine, GPS not working (No GPS ready message on power on)

You have a version2 module. Use AT+CGNSxxx instead of AT+CGPSxxx
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4 votes

SIM800 gsm Module returns 0 on AT+COPS?

It can take a while for a modem to register on the network - sometimes several minutes. Turning on CREG URCs can help you monitor what is happening: AT+CREG=1 You should now start getting +CREG ...
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  • 103k
4 votes
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Compatibility between shields

Its not just a question of the stackability of the shields and the clash of pins you also need to consider what the shields do. Stacking the GSM shield under the LCD is going to restrict is tx/rx ...
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  • 5,596
4 votes

Missing character when introducing delay in the code

If serial data is coming in, and your code is doing a delay, the incoming data is stored in a buffer (of 64 bytes). But if you wait too long, the buffer will fill-up. Once it's full, any further ...
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  • 11.1k
3 votes

GSM and GPS shield pin conflict

Looking at the PDF for the Adafruit GPS shield, pin 7 is indeed hard wired to Rx and pin 8 is hard wired to Tx. These can not be changed. Looking at the guide for the Arduino GSM shield pin 7 is ...
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  • 2,785
3 votes
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Cheapest Arduino GPRS or 3G solution

Not many possibilities (for the phone part, I suggest a GPRS/3G shield), but not wanting to discourage you, if you are thinking about "a fleet", forget about: low power (the phone radio needs power, ...
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  • 176
3 votes
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Is the SIM900 3G? Or is the SIM900A able to connect to 3G?

First of all if you are in USA you cannot use SIM 900A since it supports only Dual frequency bands.(900,1800 MHz)it supports only Asian region countries. According to Wikipedia, PTel Mobile supports ...
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  • 186
3 votes
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Error while compiling

Basically the formatting and layout of your program is completely wrong. You haven't actually defined this smsReceivingFunction anywhere. You have created a prototype to it part way through your ...
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  • 103k
3 votes
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Functions of GSM

Send sms when motion is detected by a PIR sensor Yes, write a function that does this. Basic support functions in libraries will help you send the sms and detect the PIR. You need to provide the ...
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  • 7,851
3 votes
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Arduino GPRS (GSM) shield (SIM900) no long pins

Yes, you can. There is two methods of making shields stackable: Use the quite hard to source extra long pinned headers to go right through and down (such as these https://www.adafruit.com/products/...
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  • 103k
3 votes

Is Gsm antenna effect on microcontroller working?

There are 3 possible causes that I can think of (it's difficult to say more without further details): SW bug: this is hard to confirm without actually finding the bug, but it might cause a lock-up ...
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  • 2,100
3 votes

What SMS can send to switch LED?

The code appears to be looking for an SMS that says #a0 or #a1. The logic doesn't look very robust, though. It reads a character, then waits 10ms and tries to read another. What does SIM900.read() do ...
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  • 14.5k
3 votes

SIM800 gsm Module returns 0 on AT+COPS?

If you are using linear voltage regulator such as LM7805 or LM317, then definitely you need to replace with buck converter. Since the dropout at max current 1.5A is 1.8V. Pls check the module ...
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  • 169
3 votes

Does the SIM800L works in the US?

I wanted to post an update in April 2021 on the status of this question. The SIM800L will work in the US, but T-Mobile is the only carrier that it can interface with. AT&T shut down its compatible ...
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  • 31
3 votes

SIM800L not registering to network

I am 90% sure it's a power issue. Not sure on what board/module you're using but the SIM800L/SIM900 needs a burst of current of 2 A during 577 µS (See the manual). Try using 4700 µF ...
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3 votes
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Arduino MKR GSM 1400 fails to start up without Serial Monitor

while(!Serial) {} will wait for a serial connection and in your program will block execution until it gets one. Remove it and your program should continue without the serial monitor.
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  • 1,610
3 votes
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How do I connect 4 or more Arduinos to a single shared GSM Module?

You should consider connecting one Arduino to the GSM module, and connect the 4 Arduinos together using SPI, I2C, or any other inter-hardware comms protocol. Before I knew these options existed, I ...
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2 votes

How to receive data from my server database to a variable in my Arduino?

After you send the GET request, you read the response to fill the char result [20] variable you declared: int i=0; ... if (client.connect(server, port)) { client.print("GET /locator.php?"); ... ...
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  • 1,091
2 votes

SerialGSM for GSM shield without SoftwareSerial

Never mind, i went with the GSM SMS example from arduino 1.0.5 (Don't know the version of arduino IDE that included this) and works fine. If you are considering using the SerialGSM library there is ...
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  • 1,323
2 votes

AT+CSTT throws an error

For others who reach here by search results Before this applying AT+CSTT command check if the modem is attached to GPRS using the AT+CGATT=? command. If the result is +CGATT: 0 this means the modem ...
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  • 183
2 votes

Simulation of Arduino Mega 2560 with GSM Module using Proteus

You should download this GSM Library for Proteus . You can use this library to simulate your GSM module in Proteus software. You should also check this example where they have discussed Hoe to Send ...
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