Documentation

// HC-12 - Arduino transparent link (chat bridge)
// TXD->D10, RXD->D11, VCC->5V | flash the same sketch on both boards

#include <SoftwareSerial.h>

SoftwareSerial hc12(10, 11);   // RX, TX

void setup() {
  Serial.begin(9600);
  hc12.begin(9600);            // HC-12 default baud
  Serial.println("HC-12 chat ready - type and press enter");
}

void loop() {
  // radio -> serial monitor
  while (hc12.available()) {
    Serial.write(hc12.read());
  }
  // serial monitor -> radio
  while (Serial.available()) {
    hc12.write(Serial.read());
  }
}

// HC-12 - ESP32 telemetry sender (UART2)
// TXD->GPIO16, RXD->GPIO17

unsigned long counter = 0;

void setup() {
  Serial.begin(115200);
  Serial2.begin(9600, SERIAL_8N1, 16, 17);   // RX=16, TX=17
  Serial.println("HC-12 telemetry sender");
}

void loop() {
  // Send a labeled reading once a second (replace with real sensor data)
  float fakeTemp = 20.0 + (millis() % 10000) / 1000.0;
  Serial2.printf("NODE1,%lu,%.2f\n", counter++, fakeTemp);
  Serial.printf("sent NODE1,%lu,%.2f\n", counter - 1, fakeTemp);

  // print anything that comes back
  while (Serial2.available()) Serial.write(Serial2.read());
  delay(1000);
}

#!/usr/bin/env python3
# HC-12 - Raspberry Pi receiver/logger
# TXD->GPIO15, RXD->GPIO14 | Install: pip3 install pyserial

import serial, time

port = serial.Serial("/dev/serial0", 9600, timeout=1)
print("Listening for HC-12 packets... Ctrl+C to stop")

try:
    with open("hc12_log.csv", "a") as log:
        while True:
            line = port.readline().decode(errors="ignore").strip()
            if line:
                stamp = time.strftime("%Y-%m-%d %H:%M:%S")
                print(f"[{stamp}] {line}")
                log.write(f"{stamp},{line}\n")
                log.flush()
except KeyboardInterrupt:
    print("Stopped by user")

# HC-12 - Pico MicroPython Example with AT config
# TXD->GP1, RXD->GP0, SET->GP2

from machine import UART, Pin
import time

uart = UART(0, baudrate=9600, tx=Pin(0), rx=Pin(1), timeout=300)
set_pin = Pin(2, Pin.OUT, value=1)      # HIGH = transparent mode

def at(cmd):
    """Send one AT command with SET low, return the reply."""
    set_pin.value(0)
    time.sleep_ms(50)
    uart.write(cmd + "\r\n")
    time.sleep_ms(150)
    reply = uart.read()
    set_pin.value(1)
    time.sleep_ms(80)
    return reply.decode(errors="ignore").strip() if reply else "(no reply)"

# One-time setup: channel 5, full power, confirm firmware
print("AT      :", at("AT"))          # expect OK
print("Channel :", at("AT+C005"))    # both ends must match!
print("Power   :", at("AT+P8"))      # +20 dBm
print("Version :", at("AT+V"))

counter = 0
while True:
    uart.write("PICO,{}\n".format(counter))
    print("sent PICO,{}".format(counter))
    counter += 1

    data = uart.read()
    if data:
        print("recv:", data.decode(errors="ignore").strip())
    time.sleep(1)