connection fails

[LongZoz]

when i start function->mqtt_sn,the program doesn't crash，but it's not connected to the target cloud，the program can execute to the first ok，then ... it break..... So what's the solution

`pub fn mqtt_sn(cx: mqtt_sn::Context){ defmt::info!("[TASK] mqtt_sn");

   (cx.shared.w5500_2, cx.shared.mqtt, cx.shared.mqtt_spawn_at).lock(
       |w5500_2, mqtt, mqtt_spawn_at| {
           loop {
               let now: u32 = monotonic_secs();
               defmt::info!("now is {:?}",now);
               // mqtt.subscribe(w5500, filter);
               match mqtt.process(w5500_2, now) {
                   Ok(MqttEvent::CallAfter(secs)) => {
                       *mqtt_spawn_at = Some(now + secs + 1);
                       mqtt.subscribe(w5500_2, "/filter/test1");
                       break;
                   }
                   Ok(MqttEvent::ConnAck) => {
                       defmt::info!("[MQTT] ConnAck");
                       // can subscribe to topics here
                       // not needed for this
                       mqtt.subscribe(w5500_2, "/filter/test");
                   }
                   Ok(MqttEvent::Publish(reader)) => {
                       log::warn!("should not get Publish never subscribed");
                       reader.done().unwrap();
                   }
                   Ok(MqttEvent::SubAck(_) | MqttEvent::UnSubAck(_)) => {
                       log::warn!("should not get (Un)SubAck, never (un)subscribed");
                   }
                   Ok(MqttEvent::None) => {
                       {
                           let mut data: heapless::String<16> = heapless::String::new();
                           write!(&mut data, "{:.1}", 1).unwrap();
                           mqtt.publish(w5500_2, TEMPERATURE_TOPIC, data.as_bytes())
                               .unwrap();
                       }
                       *mqtt_spawn_at = Some(now + 5);
                       break;
                   }
                   Err(e) => {
                       log::error!("[MQTT] {e:?}");
                       *mqtt_spawn_at = Some(now + 10);
                       break;
                   }
               }
           }
       },
   );

}`

[newAM]

What do the logs show?

[LongZoz]

I tried to print error，when i use tcp/ip connect another address(for example 192.168.0.1) ，mqtt connect target address(41.147.212.200) ，the result A 4,then disconnect the tcp/ip(192.168.0.1),finally return A 3 Err(e) => { match e{ w5500_mqtt::Error::StateTimeout(_c) => { defmt::info!("A "); match _c{ w5500_mqtt::State::Init => defmt::info!("2"), w5500_mqtt::State::WaitConInt => defmt::info!("3"), w5500_mqtt::State::WaitConAck => defmt::info!("4"), w5500_mqtt::State::Ready => defmt::info!("5"), } }, w5500_mqtt::Error::Disconnect => defmt::info!("A2"), w5500_mqtt::Error::TcpTimeout => defmt::info!("A3"), w5500_mqtt::Error::Decode => defmt::info!("A4"), w5500_mqtt::Error::Protocol => defmt::info!("A5"), w5500_mqtt::Error::ConnAck(_) => defmt::info!("A6"), w5500_mqtt::Error::OutOfMemory => defmt::info!("A7"), w5500_mqtt::Error::NotConnected => defmt::info!("A8"), w5500_mqtt::Error::Other(_) => defmt::info!("A9"), }

[newAM]

There are logs being printed out over UART, they contain a lot of information for debugging such as the status of the DHCP client. You can also look at a wireshark packet capture and your MQTT broker logs for more debug information.

[LongZoz]

it can send message to 192.168.0.1,as a client can receive from 192.168.0.1,but do mqtt_sn,the tcp connection（192.168.0.1） is disconnected，Perhaps it is trying to connect to mqtt's server using tcp，so （192.168.0.1） it disconnected

[newAM]

You'll definitely want to be looking at wireshark and your MQTT broker logs in that case. The UART logs would still be helpful because they'll inform you of the internal state.

[LongZoz]

I may have found the cause of the failure, if the mqtt server does not support users and passwords，i find this message in lib.rs

//! MQTT v5 client for the [Wiznet W5500] SPI internet offload chip.

//! # Limitations //! This is very basic at the moment, and will be expanded in the future. //! Does not support password protected MQTT servers. //! Only supports QoS 0: At most once delivery.`