///////////////
////   HC-12    AT mode and setup
//
//
//  connect HC-12 TX to 6
//  connect HC-12 RX to 7
//
// power up and then ground "SET pin"
//
// AT return OK
//
// max distance  AT+FU3, AT+B1200, AT+P8, AT+C009
//
// AT+Bxxx = baud rate AT+B9600
// AT+Px  = power (1-8)  lo to hi
// AT+Cxx = channels 100+
// steps=400khz AT+C001 = 433.4 mhz
// AT+C021 = 441.4mhz (21*.4=8.4)(8.4*433=441.4)
//
// AT+RX = status OK+B9600\OK+C001\...
// AT+V  = firmware HC-12_V2.4
// AT+DEFAULT = C001, 9600, FU3, +20dbm
//
// see HC-12 pdf manual for details
//
 #include <SoftwareSerial.h>

 SoftwareSerial HC12(6, 7); //HC12 TX Pin, RX Pin

 void setup() {
 Serial.begin(9600); // Serial port to computer
 HC12.begin(9600); // Serial port to HC12
 }

 void loop() {
 while (HC12.available()) { // If HC-12 has data
 Serial.write(HC12.read()); // Send to Serial monitor
 }
 while (Serial.available()) { // If Serial monitor has data
 HC12.write(Serial.read());
  }
 } //end main