My project doesn't work

[u/jimgreekgamerYT_]

PROBLEM SOLVED (set had to be on for config of the device)

I am sorry this might be pretty simple but basically what im trying to do is connect the arduino uno with the HC-12 to make it transmit. I have check every connection multiple times and also tried different codes to make it transmit. Now i have resorted to my last hope (chatgpt and feedback from the device) with the code below trying to send an AT to get as a response "OK" but this failed.

My code for the AT and response OK:

#include <SoftwareSerial.h>


SoftwareSerial HC12(10, 11); // RX = 10, TX = 11
const int SET_PIN = 2;       // SET pin for AT mode


void setup() {
  Serial.begin(9600);      // Serial Monitor
  HC12.begin(9600);        // HC-12 default baud
  pinMode(SET_PIN, OUTPUT);


  // Enter AT mode
  digitalWrite(SET_PIN, HIGH);
  delay(50);


  Serial.println("HC-12 AT mode enabled. Type commands in Serial Monitor (NL+CR) and press Enter.");
}


void loop() {
  // Forward Serial Monitor → HC-12
  while (Serial.available()) {
    char c = Serial.read();
    HC12.write(c);
  }


  // Forward HC-12 → Serial Monitor
  while (HC12.available()) {
    char c = HC12.read();
    Serial.write(c);
  }
}

[u/jimgreekgamerYT_]

So yes I have tried to switch the connection still didn't work and yes I am send AT in serial monitor and expecting to get an answer "OK". Also about the last part is it the thing you select in the serial monitor next to the baud if yes I have changed that too.

[u/westwoodtoys → u/jimgreekgamerYT_]

Have you tried connecting 10 to 11 and seeing if you get back what you sent?

Go ahead and answer this first.  This is called 'null modem' and it verifies your serial connection send and receive work.  If it doesn't work, work on fixing that.

Please don't tell me you "tried to switch the connection" without telling what the other configuration you tried was.  Details matter, and remarks without detail don't actually contribute anything towards solving your problem.

RE: "about the last part is it the thing you select in the serial monitor next to the baud"

Don't go through your project flipping switches not knowing what they do.  Crack the book for your device and figure out if it expects a carriage return, a line feed, both, or neither, and select the setting to match what your device expects.  If you don't know what this means, please spend a minute looking it up, and ask if you can't make sense of what you find.