Auto resend on NACK

[alowhum]

@mfalkvidd Thank you so much for the explanation! I feel I'm getting a grasp on things.

[Mark Swift]

@mfalkvidd said in Auto resend on NACK:

https://forum.mysensors.org/post/33832

Would someone be kind enough to point me in the direction of a good software acknowledgement example? I've been building MySensors for 4 years and still have sensors that don't send reliable messages. While most have been replaced with ESP's - these sensors are extremely remote and battery powered (MySensors wins here!).

Currently I use:

void resend(MyMessage &msg, int repeats) {
        int repeat = 1;
        const int repeatDelay = 100;
        boolean sendOK = false;
        while ((sendOK == false) and (repeat <= repeats)) {
                if (send(msg) == true) {
                        sendOK = true;
                } else {
                        sendOK = false;
                        #ifdef MY_DEBUG
                        Serial.print(F("Send error: "));
                        Serial.println(repeat);
                        #endif
                        repeat++;
                        wait(repeatDelay);
                }
        }
}

But this doesn't seem to ensure reliable delivery (some nodes send 10 msgs before sleeping). Often I get multiple messages arriving (I assume this is the burst), but some (often vital) never make it.

[electrik]

You will get multiple messages, if the message arrives correctly but the hardware ACK doesn't.

Do you have a repeater in between the sender and gateway? It could be that the repeater does receive the initial message (and the sensor gets a hardware ACK), but that never reaches the gateway because of a transmission error between the repeater and the gateway.