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Add note about MEMP_NUM_SYS_TIMEOUT in four apps

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This commit is contained in:
Dirk Ziegelmeier
2019-03-20 20:50:17 +01:00
parent a329bdd607
commit 4b10b4dab3
4 changed files with 25 additions and 18 deletions
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38
doc/mqtt_client.txt
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@@ -3,11 +3,13 @@ MQTT client for lwIP
Author: Erik Andersson
Details of the MQTT protocol can be found at:
http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html
http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html
-----------------------------------------------------------------
1. Initial steps, reserve memory and make connection to server:
You need to increase MEMP_NUM_SYS_TIMEOUT by one if you use MQTT!
1.1: Provide storage
Static allocation:
@@ -19,34 +21,34 @@ Dynamic allocation:
if(client != NULL) {
example_do_connect(&client);
}
1.2: Establish Connection with server
void example_do_connect(mqtt_client_t *client)
{
struct mqtt_connect_client_info_t ci;
err_t err;
/* Setup an empty client info structure */
memset(&ci, 0, sizeof(ci));
/* Minimal amount of information required is client identifier, so set it here */
/* Minimal amount of information required is client identifier, so set it here */
ci.client_id = "lwip_test";
/* Initiate client and connect to server, if this fails immediately an error code is returned
otherwise mqtt_connection_cb will be called with connection result after attempting
to establish a connection with the server.
otherwise mqtt_connection_cb will be called with connection result after attempting
to establish a connection with the server.
For now MQTT version 3.1.1 is always used */
err = mqtt_client_connect(client, ip_addr, MQTT_PORT, mqtt_connection_cb, 0, &ci);
/* For now just print the result code if something goes wrong */
if(err != ERR_OK) {
printf("mqtt_connect return %d\n", err);
}
}
Connection to server can also be probed by calling mqtt_client_is_connected(client)
Connection to server can also be probed by calling mqtt_client_is_connected(client)
-----------------------------------------------------------------
2. Implementing the connection status callback
@@ -57,11 +59,11 @@ static void mqtt_connection_cb(mqtt_client_t *client, void *arg, mqtt_connection
err_t err;
if(status == MQTT_CONNECT_ACCEPTED) {
printf("mqtt_connection_cb: Successfully connected\n");
/* Setup callback for incoming publish requests */
mqtt_set_inpub_callback(client, mqtt_incoming_publish_cb, mqtt_incoming_data_cb, arg);
/* Subscribe to a topic named "subtopic" with QoS level 1, call mqtt_sub_request_cb with result */
/* Subscribe to a topic named "subtopic" with QoS level 1, call mqtt_sub_request_cb with result */
err = mqtt_subscribe(client, "subtopic", 1, mqtt_sub_request_cb, arg);
if(err != ERR_OK) {
@@ -69,16 +71,16 @@ static void mqtt_connection_cb(mqtt_client_t *client, void *arg, mqtt_connection
}
} else {
printf("mqtt_connection_cb: Disconnected, reason: %d\n", status);
/* Its more nice to be connected, so try to reconnect */
example_do_connect(client);
}
}
}
static void mqtt_sub_request_cb(void *arg, err_t result)
{
/* Just print the result code here for simplicity,
normal behaviour would be to take some action if subscribe fails like
/* Just print the result code here for simplicity,
normal behaviour would be to take some action if subscribe fails like
notifying user, retry subscribe or disconnect from server */
printf("Subscribe result: %d\n", result);
}