HC-05 disconnects after about 3 seconds

Bugs and Other Issues
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1

Using the (I'll say standard) Bluetooth control videos on YouTube, I programed the Arduino and created the app from MIT app inventor.
The HC-05 is paired with the standard code 1234.
Launch the app
select the HC-05
shows connected
can turn the LED on and off for about 3 to 5 seconds
and then it seems to stop talking to the HC-05

click list picker and the HC-05 shows up
but when I select it,
my phone screen goes black for several seconds
and then pop up window at the bottom of phone stating
"BluetoothCtrl isn't responding"
with selection to close app
or wait

if I select wait, and then the on or off buttons of the app, I get
"error515: not connected to a bluetooth device"

I have to close and relaunch the app and it lets me control the LED again for 3 to 5 seconds.

Elegoo UNO R3
HC-05 seems to be generic
Samsung Galaxy S25

Anyone have a fix? And is this a common issue?

2

It would really help if you provided a screenshot of your relevant blocks, so we can see what you are trying to do, and where the problem may be.

To get an image of your blocks, right click in the Blocks Editor and select "Download Blocks as Image". You might want to use an image editor to crop etc. if required. Then post it here in the community.

Taifun

Trying to push the limits! Snippets, Tutorials and Extensions from Pura Vida Apps by icon24 Taifun.

3

So, Taifun, thanks for the attempt to help a newbie,
But I just got it to work. There are a few possibilities that could have caused it not to work. Unfortunately I didn't save the original code so I can't say exactly what was the problem. (won't be making that mistake again).
1st, I cleaned up my Arduino code by lining up each line of code. And I changed my IF statement. and finally, when uploading new code, I unplugged the HC-05 module.
I was totally convinced the problem was with my phone and possibly some sort of bluetooth setting on the phone because I could control the LED for a few seconds.

My ultimate goal is to control an Adafruit 8 channel feather wing with my nRF52832 over BLE using an app creted on MIT app inventor.

4 
char Incoming_value = 0;

void setup()

{

Serial.begin(9600);

pinMode(13, OUTPUT);

}

void loop()

{

if(Serial.available())

{

Incoming_value = Serial.read();

Serial.print(Incoming_value);

Serial.print("\n");

if(Incoming_value == '1')

digitalWrite(13, HIGH);

else if(Incoming_value == '0')

digitalWrite(13, LOW);

}

}
5

Dear @Eric_Michalek,
happy that it worked for you, but please let me tell you some hints, anyway.

When you use the Arduino 'Hardware Serial' (i.e. the simple "serial()"), please be aware that this is the serial line intended to be used for the serial monitor and for programing the board (which Arduino board do you use ?), therefore when you use that line to connect also the BT, everything that you send on that line is sent to both the BT and the serial monitor, so if you want to make an echo on the serial monitor of what is arriving on the BT input, and you use for that purpose a serial.print(); this is sent also back to the BT (i.e. your app). To avoid collisions typically the BT is connected to other pins of the board (2,3 or 10,11 depending on the board), that are "mapped" as a serial line by using the library SoftwareSerial (you can find it on any Arduino forum or on GitHub).
Having said that, please be aware also that the BLE comm's. though is called BT, in effect is dramatically different and in your app you shall load the specific extension.
Please refer to the @abg FAQ on BLE at the following link:

and on the Arduino board (in your case, you say you will use the nRF52832 ) also the library that manages the BLE is fairly different from the simple SoftwareSerial. To avoid your hair become white in a while in attempting to use the BLE, please consider to use the Classic BT, instead, or read at least one of the numerous posts on the forum pertaining to the same topic (BLE from/to Arduino).

Las, but not least, whether you'll intend to use the delay() function in Arduino, since in some versions it blocks completely the CPU, please consider to use one made by you, instead, like:

void myDelay(unsigned long Timeout)
{
unsigned long now = millis();
while((millis()-now) < Timeout) ; // do nothing but leave the CPU alive
}

and to call it:

myDelay(1000); // example to delay 1 second

Best wishes for your project !
Cheers.

PS if you search the forum with the tag nRF52832 you'll find that many other users had "big" troubles in trying to use it. Be careful :hugs:

6

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