We have devices that have low signal so they have to reconnect to AWS a lot. We have a watchdog timer with a 100s timeout that we feed every 10 seconds in the control loop.
Occasionally we see the device hit the 100s watchdog timer and reset when connecting to AWS.
Environment:
Only see with devices with low signal
nRF Connect SDK v3.5.99-ncs1-1
SDK and tool chain: v2.6.1
Tf-M v2.0.0
MODEM_INFO_FW_VERSION: mfw_nrf9160_1.3.6
LTE-M cellular connected in the U.S.
Configs:
CONFIG_AWS_IOT_CONNECT_TIMEOUT_SECONDS=30
Code:
LOG_INF("Connecting to AWS IoT broker");
const struct aws_iot_config config = {
.client_id = client_id_buf,
.host_name = CONFIG_AWS_IOT_BROKER_HOST_NAME,
};
int start_time = k_uptime_get();
// This is synchronous and cant take a while (30+ seconds)
err = aws_iot_connect(&config);Logs:
[00:06:04.668,487] [0m<inf> cloud: Connecting to AWS IoT broker [00:06:04.674,621] [0m<dbg> mqtt_helper: broker_init: Resolving IP address for [deleted] [00:06:06.815,155] [0m<dbg> mqtt_helper: broker_init: IPv4 Address found [deleted] (AF_INET) [00:06:06.823,944] [0m<dbg> mqtt_helper: mqtt_state_set: State transition: MQTT_STATE_DISCONNECTED --> MQTT_STATE_TRANSPORT_CONNECTING // WDT hit and reconnects �[1;34m[Sec Thread] Secure image initializing![0m [1;34mBooting TF-M v2.0.0[0m *** Booting nRF Connect SDK v3.5.99-ncs1-1 *** [00:00:00.258,026] [0m<inf> main: main started[0m [00:00:00.262,512] [1;33m<wrn> main: reset cause 0x10[0m Another example: [00:24:59.793,365] [0m<inf> cloud: Connecting to AWS IoT broker[0m [00:24:59.799,530] [0m<dbg> mqtt_helper: broker_init: Resolving IP address for [0m [00:25:01.423,126] [0m<dbg> mqtt_helper: broker_init: IPv4 Address found(AF_INET)[0m [00:25:01.431,762] [0m<dbg> mqtt_helper: mqtt_state_set: State transition: MQTT_STATE_DISCONNECTED --> MQTT_STATE_TRANSPORT_CONNECTING[0m [00:26:03.737,792] [0m<dbg> mqtt_helper: mqtt_state_set: State transition: MQTT_STATE_TRANSPORT_CONNECTING --> MQTT_STATE_TRANSPORT_CONNECTED[0m [00:26:03.750,396] [0m<dbg> mqtt_helper: mqtt_state_set: State transition: MQTT_STATE_TRANSPORT_CONNECTED --> MQTT_STATE_CONNECTING[0m [00:26:03.762,176] [0m<dbg> mqtt_helper: client_connect: Using send socket timeout of 60 seconds[0m [00:26:03.770,935] [0m<dbg> mqtt_helper: mqtt_helper_connect: MQTT connection request sent[0m [00:26:03.779,235] [0m<dbg> mqtt_helper: mqtt_helper_poll_loop: Took connection_poll_sem[0m [00:26:03.787,322] [0m<dbg> mqtt_helper: mqtt_helper_poll_loop: Starting to poll on socket, fd: 0[0m [00:26:03.796,173] [0m<dbg> mqtt_helper: mqtt_helper_poll_loop: Polling on socket fd: 0[0m �[1;34m[Sec Thread] Secure image initializing![0m [1;34mBooting TF-M v2.0.0[0m *** Booting nRF Connect SDK v3.5.99-ncs1-1 *** [00:00:00.258,087] [0m<inf> main: main started[0m [00:00:00.262,573] [1;33m<wrn> main: reset cause 0x10[0m // Another Example [00:16:36.075,561] [0m<inf> cloud: Connecting to AWS IoT broker[0m [00:16:36.081,726] [0m<dbg> mqtt_helper: broker_init: Resolving IP address for [0m [00:16:37.178,619] [0m<dbg> mqtt_helper: broker_init: IPv4 Address found(AF_INET)[0m [00:16:37.187,408] [0m<dbg> mqtt_helper: mqtt_state_set: State transition: MQTT_STATE_DISCONNECTED --> MQTT_STATE_TRANSPORT_CONNECTING[0m [00:17:50.167,114] [0m<dbg> mqtt_helper: mqtt_state_set: State transition: MQTT_STATE_TRANSPORT_CONNECTING --> MQTT_STATE_TRANSPORT_CONNECTED[0m [00:17:50.179,687] [0m<dbg> mqtt_helper: mqtt_state_set: State transition: MQTT_STATE_TRANSPORT_CONNECTED --> MQTT_STATE_CONNECTING[0m [00:17:50.191,497] [0m<dbg> mqtt_helper: client_connect: Using send socket timeout of 60 seconds[0m [00:17:50.200,225] [0m<dbg> mqtt_helper: mqtt_helper_connect: MQTT connection request sent[0m [00:17:50.208,557] [0m<dbg> mqtt_helper: mqtt_helper_poll_loop: Took connection_poll_sem[0m [00:17:50.216,613] [0m<dbg> mqtt_helper: mqtt_helper_poll_loop: Starting to poll on socket, fd: 0[0m [00:17:50.225,494] [0m<dbg> mqtt_helper: mqtt_helper_poll_loop: Polling on socket fd: 0[0m �[1;34m[Sec Thread] Secure image initializing![0m [1;34mBooting TF-M v2.0.0[0m *** Booting nRF Connect SDK v3.5.99-ncs1-1 *** [00:00:00.258,117] [0m<inf> main: main started[0m [00:00:00.262,603] [1;33m<wrn> main: reset cause 0x10[0m
Sometimes I also see that connecting took longer than the 30 second config we have set.
[00:09:30.122,406] [0m<inf> cloud: aws_iot_connect() took 52963 ms
Here's where it took so long:
[00:08:38.476,684] [0m<dbg> mqtt_helper: mqtt_state_set: State transition: MQTT_STATE_DISCONNECTED --> MQTT_STATE_TRANSPORT_CONNECTING[0m
[00:09:27.934,753] [0m<dbg> mqtt_helper: mqtt_state_set: State transition: MQTT_STATE_TRANSPORT_CONNECTING --> MQTT_STATE_TRANSPORT_CONNECTED[0m