ATTAG handshake between blaster and host

Working on a simple handshake protocol between the blaster and the host using the 433MHz connection.

Question: Why not Blutooth or Wifi, ESP32 got both already?

Answer: Yes it might also work with BT or Wifi and maybe I am wasting too much energy on the 433MHz component but there are certain advantages in my opinion. First is the range, you can easily increase the range by using a long antenna on the host and there is no failing or loss of connection. Simple serial messaging. The disadvantage is the speed, so I have to keep the sent strings as short as possible. However I am no specialist, if anyone wants to provide a reliable BT or WiFi alternative in a later mod, go for it. It would reduce costs of course.

So this is my plan:

  • Blaster: asks host
  • Host: replies with game settings if detected and adds blaster to player list
  • Blaster: replies with confirmation of received game data
  • Host: replies with status “ready”
// doing the handshake between blasters and server

// doing the handshake between blasters and server
void dohandshake(lv_event_t *e) {
  Serial.println("We are at handshake.");
   // is HC12 available?
   if (hc12.available()) {
    // Serial.write(;    
    // get the message
    message = hc12.readString();    

    // @G0XX = attag blaster asking to join, XX=id of the blaster
    // @G1XX = attag blaster received game data and is ready to start, XX=id of the blaster

    // Reading messages from the blasters
    if (message.substring(0,2)=="@G0") {
       // adding blaster to the player list, but don't set on confirmed yet
       // sending game data
    } else if (message.substring(0,2)=="@G1") {
       // setting blaster to confirmed
       // sending ready status                

The ID of the blaster could be transmitted in hex of course, this would shorten the string to 4 chars, 16 players (0-F) should be quite enough. There needs to be some sort of identification, so the server isn’t collecting any garbage from somewhere else, I guess the @G should do it, it isn’t rocket science here and anything in range at 433MHz would be some garage doors, weather stations and toy vehicles.

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