GolamMostafa:
1. Check that you have connected the HC05 Module with UNO as per following diagram. The voltage divider circuit is needed as the RX-pin of HC05 is not 5V tolerant.
2. Is the Red-LED of the BT Module continuously blinking?
3. Have you installed a Bluetooth Terminal (BTT) in your android based smart phone?
4. Check that the smart phone has detected your BT Module. If SN is asked, enter 0000 or 1234; they usually work.
5. Connect your BTT with the BT module. Check that the RED-LED is now blinking once a while.
6. Upload the following sketch in the flash of your UNO.
#include <SoftwareSerial.h>
SoftwareSerial BTserial(2, 3); // RX | TX
// Connect the HC-05 TX to Arduino pin 2(as RX).
// Connect the HC-05 RX to Arduino pin 3 (as TX) through a voltage divider.
void setup()
{
Serial.begin(9600);
BTserial.begin(9600);
}
void loop()
{
if (BTserial.available())
{
byte x = BTserial.read();
Serial.write(x);
}
if (Serial.available())
{
byte y = Serial.read();
BTserial.write(y);
}
}
**7.** Check the functionality of the communication link: BTT <----> BT <----> UNO <----> Serial Monitor
- No problem
- No problem
- Yes, BTT is installed
- BTT can detect BT but can not pair - same error
- BTT not pair with BT
- Have almost same sketch
- Functionality between BT-Arduino-Serial Monitor works and can set it via AT commands
... looks like HM BT chip is not compatible with all my Bluetooth devices