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A simple MQTT library for the ESP8266
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A.M. Rowsell dee07e5fe7
 Subscribe feature now works. See huge commit log! 
Quite a few updates. Subscription feature is now working,
which is great. This has been tested with mosquitto broker
as well as Adafruit IO, and it works perfectly with both.

I tried to compile this project as a library (see the changes
to Makefile) but when I used that .a file in another project
the linking process failed. More research needed, I've never
tried to do that before.

I compressed some of the case statements in mqtt_send as they
are so similar, it's a waste of code space to duplicate them.
Disconnect and ping are identical except for one byte, and
unsubscribe and subscribe differ in only a few lines.

The data receive callback now prints information on what kind
of packet/data was received; again, mostly useful during
debugging, but the framework is there to expand it to do
useful things like triggering other tasks/timers, etc.

There is now a keepalive ping timer which keeps both the MQTT
and thus the TCP connection alive. It currently pings every 5
seconds, though I might change that closer to the timeout
maximum (50 seconds).

Signed-off-by: A.M. Rowsell <amrowsell@frozenelectronics.ca>
2018-08-19 02:19:25 -04:00
.gitignore Implemented basic receive functionality. See full log. 2018-08-18 14:58:03 -04:00
LICENSE Changed license to Mozilla Public License v2.0 2018-08-18 06:11:39 +00:00
Makefile Subscribe feature now works. See huge commit log! 2018-08-19 02:19:25 -04:00
mqtt.c Subscribe feature now works. See huge commit log! 2018-08-19 02:19:25 -04:00
mqtt.h Subscribe feature now works. See huge commit log! 2018-08-19 02:19:25 -04:00
README.md Fixed the markdown in README 2018-08-16 19:01:14 +00:00
strtoarr.py Implemented basic receive functionality. See full log. 2018-08-18 14:58:03 -04:00
user_config.h Initial commit 2018-08-13 23:34:17 -04:00

README.md

MQTT Library for ESP8266 SDK

written by Alexander Rowsell (MrAureliusR)
Released under the terms of the MIT License -- see LICENSE for more detail.

Summary

While working on a series of tutorials for Hackaday, I realized MQTT would be the perfect solution for one of the projects I was presenting. However, I didn't want to use a pre-existing MQTT library - that would be boring, and I wouldn't be able to teach the readers as much. Instead, I started to write one from scratch.

At this point, it's a bit messy. It still needs a lot of work. This documentation will help me keep everything organized and easy-to-use.

API Structures

  uint8_t ip[4];
  uint32_t port;
  uint32_t localPort;
  uint8_t *client_id;
  uint8_t *topic_name;
  uint8_t qos_level;
  uint8_t *username;
  uint8_t *password;
  char valid_connection;
  struct espconn *activeConnection;
} mqtt_session_t;```

This is the main structure that contains all the information about the connection to the server. The IP address, port, client\_id, topic\_name, username, and password are all specified here by the end user. localPort is set by the API, and qos\_level should be set to 0. *activeConnection will point to the espconn struct that represents the TCP connection to the server. The end-user shouldn't need to touch anything in this struct.

## API Functions

### `mqtt_connect(mqtt_session_t *session, uint8_t *username, uint8_t *password)`  
This function establishes a TCP connection with the server specified in session->ip, on session->port. Most MQTT brokers listen on port 1883 for unencrypted packets, and on 8883 for TLS connections. This API currently only supports unencrypted packets on 1883. However, the port still needs to be specified, in case you use a non standard port.