funcion para leer la frecuencia de transceptor por puerto serie (Arduino)

read_description.cpp

void read_frequency() {
    if (Serial.available() <= 0)
        return;

    String description = read_serial_message(0xFD);

    if (!is_valid(description))
        return;

    return parse_frequency(description);
}

int parse_frequency(const String &description) {
    frequency = 0;
    for (byte i = 9 - mode_735; i >= 5; i--)
        frequency = (frequency * 100) + hex_2_dec((byte) description.charAt(i));
    return frequency;
}

int hex_2_dec(byte hex_number) {
    return (hex_number >> 4) * 10 + (hex_number & 0x0F);
}

bool is_valid(const String &description) {
    if (description.length() + mode_735 == 11)
        return false;

    char char_at_2 = description.charAt(2);
    char char_at_3 = description.charAt(3);
    char char_at_4 = description.charAt(4);

    // bool valid_CIV_address_at_2 = char_at_2 == CIV_Address && (char_at_4 == 0x00 || char_at_4 == 0x05);
    // bool valid_CIV_address_at_3 = char_at_3 == CIV_Address && (char_at_4 == 0x00 || char_at_4 == 0x03);
    // return valid_CIV_address_at_3 || valid_CIV_address_at_2;
    return char_at_3 == CIV_Address && (char_at_4 == 0x00 || char_at_4 == 0x03)
           ||
           char_at_2 == CIV_Address && (char_at_4 == 0x00 || char_at_4 == 0x05);
}

String read_serial_message(int end_character) {
    char character;
    String description = "";
    unsigned long serial_read_watchdog = millis();
    while ((byte) character != end_character) {
        if (Serial.available() > 0) {
            character = Serial.read();
            description.concat(character);
        }

        // Timeout if 500 millis have passed and we got no 0xFD
        if (millis() - serial_read_watchdog >= 500)
            return "";
    }
    return description;
}