Sending AT commands through serial monitor (Arduino Uno)

Projects Programming
1

Hello Folks

I'm using the Arduino Uno board with GSM Module (SIM 900). I want to send AT commands through the serial monitor. I load the following code and send AT commands through the serial monitor. In response AT + some garbage value received on the serial monitor output window. So basically, when i sent AT as command in dialog box of serial monitor, in response I get AT + some garbage value instead of OK. Before building the project i just want to check whether my AT commands are working are not.

Any help is appreciated.

Code: (nothing is there)

void setup() {
// put your setup code here, to run once:

}

void loop() {
// put your main code here, to run repeatedly:

}

I have uploaded the code in arduino uno. Here Rx (Arduino Uno) is connected to Rx (GSM module) and Tx (Arduino Uno) is connected to Tx (GSM module).

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2

Try a wire from the Reset pin to the Ground pin (or just holding down the Reset button). If that works, the problem is that the ATmega is trying to drive the TX pin. Perhaps setting Pin 0 and Pin 1 to INPUT would help.

3

Test the SIM900 with a standalone serial adapter; those can be purchased on ebay for under $2 including shipping. The ones I have had good luck with look like this (black, with the little 3.3v / 5v switch, search CH340G 6 pin to find them) - https://www.ebay.com/itm/TTL-USB2-0-To-6Pin-CH340G-Converter-for-STC-Arduino-PRO-Instead-of-CP2102-PL2303/191196018631 No specific endorsement of that vendor; there are multiple vendors who sell similar ones.