user62216: I’m trying to send and receive data from my laptop to arduino nano via hc05 Bluetooth for a rocket flight computer. For some reasons which I don’t know, I can send data from processing software using myPort.write() but cannot send a String back from arduino back to processing for telemetry purpose. At some point it was working, then stopped. I tried another code from HowToMechatronics.com and still it didn’t work. I’m using the Serial.println function on Hardware serial.
Pls help
In the processing code, I use all necessary libraries and functions e.g serialEvent(), myPort.bufferUntil(\n), myPort.readStringUntil(‘\n’)
[1]: https://i.stack.imgur.com/V3Jqn.jpg![enter image description here](https://i.stack.imgur.com/usvad.jpg)

user62216: Update: After trying numerous codes, I was  sure that it wasn’t a software problem. I then removed the Hc05 module from the circuit, and I was able to put it in AT mode(this means my module is working fine). This leaves only one possible problem I.e the circuit. I used a multimeter to measure the voltage between Hc05 RX and GND. I got 1.8v(but how?). After retracing the connections, I figured out the problem was with the voltage divide I used to step down 5v to 3.3v. I used a 2k Ohm resistor in place of a 1k, and a 1k in place of the 2k resistor. So that’s why I’m getting a voltage of around 1.8v. Turns out 1.8v is too low for Hc05 rx pin to use. After correcting it, everything works fine

62216: <p>I’m trying to send and receive data from my laptop to arduino nano via hc05 Bluetooth for a rocket flight computer. For some reasons which I don’t know, I can send data from processing software using myPort.write() but cannot send a String back from arduino back to processing for telemetry purpose. At some point it was working, then stopped. I tried another code from HowToMechatronics.com and still it didn’t work. I’m using the Serial.println function on Hardware serial.
Pls help</p>
<p>In the processing code, I use all necessary libraries and functions e.g serialEvent(), myPort.bufferUntil(\n), myPort.readStringUntil(‘\n’)<img src="https://i.stack.imgur.com/fKiJY.jpg" alt="enter image description here" /></p>
<p>[1]: <a href="https://i.stack.imgur.com/V3Jqn.jpg!%5Benter" rel="nofollow noreferrer">https://i.stack.imgur.com/V3Jqn.jpg![enter</a> image description here](<a href="https://i.stack.imgur.com/usvad.jpg" rel="nofollow noreferrer">https://i.stack.imgur.com/usvad.jpg</a>)<img src="https://i.stack.imgur.com/SR1xB.jpg" alt="enter image description here" /><img src="https://i.stack.imgur.com/R3Uog.jpg" alt="enter image description here" /></p>
 62216: <p>Update: After trying numerous codes, I was  sure that it wasn’t a software problem. I then removed the Hc05 module from the circuit, and I was able to put it in AT mode(this means my module is working fine). This leaves only one possible problem I.e the circuit. I used a multimeter to measure the voltage between Hc05 RX and GND. I got 1.8v(but how?). After retracing the connections, I figured out the problem was with the voltage divide I used to step down 5v to 3.3v. I used a 2k Ohm resistor in place of a 1k, and a 1k in place of the 2k resistor. So that’s why I’m getting a voltage of around 1.8v. Turns out 1.8v is too low for Hc05 rx pin to use. After correcting it, everything works fine</p>
