Bluetooth xm-15b & Ln298

Hello,

I have a problem while connecting arduino UNO with the bluetooth module Xm-15b and the driver LN298. I am making a 2 wheels robot controlled by bluetooth. The problem is that when i am connected to the computer port ("COM4"), it works; but if i use the 9v battery instead of the computer, although everything turn on, the connection with my cellphone (using BluetoothSerialController.apk) doesnt work when i reconnect it to the module.

the code is the following:

int in1 = 7; int in2 = 6; int in3 = 5; int in4 = 4; void setup() { ** Serial.begin(9600);** ** pinMode (in1,OUTPUT);** ** pinMode (in2,OUTPUT);** ** pinMode (in3,OUTPUT);** ** pinMode (in4,OUTPUT);** } void loop() { ** if (Serial.available()>0)** ** {** ** char nodato = Serial.read();** ** char dato = char (nodato);** ** if (dato == '0')** ** {** ** digitalWrite (in1,LOW);** ** digitalWrite (in2,HIGH);** ** digitalWrite (in3,HIGH);** ** digitalWrite (in1,LOW);** ** }** ** if (dato == '1')** ** {** ** digitalWrite (in1,HIGH);** ** digitalWrite (in2,LOW);** ** digitalWrite (in3,HIGH);** ** digitalWrite (in1,LOW);** ** }** ** if (dato == '2')** ** {** ** digitalWrite (in1,HIGH);** ** digitalWrite (in2,LOW);** ** digitalWrite (in3,HIGH);** ** digitalWrite (in1,LOW);** ** }** ** if (dato == '3')** ** {** ** digitalWrite (in1,HIGH);** ** digitalWrite (in2,LOW);** ** digitalWrite (in3,LOW);** ** digitalWrite (in1,HIGH);** ** }** ** if (dato == '4')** ** {** ** digitalWrite (in1,LOW);** ** digitalWrite (in2,LOW);** ** digitalWrite (in3,LOW);** ** digitalWrite (in1,LOW);** ** }** ** }** }

the connections are these:

xm-15b:

The common 9 V battery can't supply enough current for a robot. You'll need to use a better power source. A decent quality/capacity (the cheap ones often lie outrageously about their capacity) USB power pack might be an easy solution, perhaps you already have one on hand.

sebi6576 provided a bit more information in their cross post:

sebi6576: the connections are like these:

XM-15B: 5v -> 5v arduino (using protoboard) gnd -> gnd arduino ("" "") rx -> tx arduino tx -> rx arduino

Ln298: +12v -> 5v arduino (using protoboard) //I use 12v, because the wheels dont move if i use +5v gnd - > gnd arduino (using protoboard) in1 -> pin 4 arduino in2 -> pin 5 arduino in3 -> pin 6 arduino in4 -> pin 7 arduino

wheels are connected in each side of the ln298 driver, using 2 wires for wheel.