# HC-05 AT Command error

**URL:** <https://forum.arduino.cc/t/hc-05-at-command-error/668492>\
**Category:** Networking, Protocols, and Devices\
**Created:** [August 3, 2020, 4:54am UTC](https://forum.arduino.cc/t/hc-05-at-command-error/668492 "2020-08-03T04:54:40Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jjunki20](https://avatars.discourse-cdn.com/v4/letter/j/ac91a4/32.png) [@jjunki20](https://forum.arduino.cc/u/jjunki20)\
**Post date:** [August 3, 2020, 4:54am UTC](https://forum.arduino.cc/t/hc-05-at-command-error/668492/1 "2020-08-03T04:54:40Z")

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Hello Guys

I am working on the HC-05 bluetooth module and Arduino UNO.

```cpp
#include <SoftwareSerial.h>

SoftwareSerial mySerial(10, 11); // RX, TX

void setup() {

Serial.begin(9600);

pinMode(9,OUTPUT); digitalWrite(9,HIGH);

Serial.println("Enter AT commands:");

mySerial.begin(38400);

}

void loop()

{

if (mySerial.available())

Serial.write(mySerial.read());

if (Serial.available())

mySerial.write(Serial.read());

}

```

This is the code I am using.  
As wire connection is really simple, I am not adding it.

Once I upload the code and open the serial monitor with Baudrate 38400 and Both NL&CR option,  
what I can see it "⸮x⸮⸮x⸮⸮x⸮xxxx⸮⸮" This very weird characters. If I change the baud to 9600, I can see  
"Enter AT commands" this message. But, I cannot give any AT Commands.

Please advise me guys. Thanks

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<div class="post-metadata">

**Author:** ![sterretje](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/sterretje/32/391294_2.png) [@sterretje](https://forum.arduino.cc/u/sterretje)\
**Post date:** [August 3, 2020, 5:23am UTC](https://forum.arduino.cc/t/hc-05-at-command-error/668492/2 "2020-08-03T05:23:43Z")

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Can't really help (lack of experience with bluetooth modules) but the baud rate on serial needs to match the setting of the serial monitor.

And it will have no effect the communication with the HC05 so you can leave that at 38400.

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**Author:** ![system](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/system/32/1140315_2.png) [@system](https://forum.arduino.cc/u/system)\
**Post date:** [May 6, 2021, 11:21am UTC](https://forum.arduino.cc/t/hc-05-at-command-error/668492/3 "2021-05-06T11:21:16Z")

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