Arduino - Bluetooth - Putty

Hello Everyone,

I am trying to communicate between my computer and an Arduino UNO board via Bluetooth. I made all the appropriate connections between the Bluetooth and the Arduino (Rx->Tx, Tx->Rx, VCC and GND). I uploaded a very simple code on the Arduino board (When I press a 1, the LED connected through pin 13 should turn ON and when I press a 0 it should turn off). I tried this code on the Serial Monitor of the Arduino program and it works perfectly fine !

The problem is when I use the Putty program to send commands, nothing happens when I press 1 or 0. I've been trying to troubleshoot this issue for a week approximately and I can't figure out the problem.

If there is anyone who can help me solve this issue, I would be very glad and appreciated !!

Thank You !!

Farouk Moukaddem

What COM and baud rate are you using on putty? Most Bluetooth modules are defaulted at 9600 baud, and of course must be paired to the computer. Does your BT module have a connection LED? It blinks when it is NOT connected and is solid when it is.

Thank you for your reply !!

When I connect the Bluetooth, the device manager states that the connection has to be through COM 17. Later on, I configured the settings on the Putty software (Serial COM17, Baud:115200) and then as soon as I applied these settings, the LINK button turns on on the bluetooth shield

However, whenever I send the commands on Putty, nothing happens. :/

Do you have any idea what the problem is ?

Thank you so much, I really appreciate your help

Try setting the baud rate in your code to 9600 and set the baud rate in putty to 9600 as well.

faroukm: I tried this code on the Serial Monitor of the Arduino program and it works perfectly fine ! The problem is when I use the Putty program to send commands, nothing happens

Are both Putty and Arduino running at the same speed? Are you trying to do this with the USB cable still connected? If so, disconnect the cable and try again.

Yes yes, the putty and the Arduino are running at the same speed. I tried changing the speed in both the Putty and Arduino to 9600, but it still doesn't work.

I also tried disconnecting the cable and connecting the system (Arduino-Bluetooth) to a power supply, but it still doesn't work.

However, when I try to send a message from the Arduino to the Putty, the Putty receives the message and the code is working. The problem is from the other way around (When I send a bit from Putty to Arduino). :/

Post your code.

This is the code that I'm using :

void setup() {pinMode(12, OUTPUT); Serial.begin(115200);}

void loop() {char c =; if (c=='0') digitalWrite(12,LOW); if (c=='1') digitalWrite(12,HIGH); delay(500);}

Thank you very much for your concern !

You don’t have “if(Serial.available() > 0)”
And as I stated earlier,most Bluetooth modules come with a default baud rate of 9600.

The code isn't pretty but looks as if it should work except that you're using pin12 instead of pin13. Do you have an LED and series resistor connected to pin12? If so, have you confirmed that it works?

Given that you have inbound communication working, you could echo the received characters back to the Serial port to give you a second way to confirm that they are being received.

I'm sorry, I meant to say earlier that I am connecting the LED in series with the resistor accross Pin 12 of the Arduino just like in the code.

I have also tried using a Baud rate of 9600, and I still have the same problem. I'm absolutely sure that the Putty is not reading the bit '1' when I'm sending it, that's why the LED is not turned on and I have no idea how to Troubleshoot this issue.

Do you have any idea how to solve this ?