ESP8266 Community Forum

Hi Everyone,
Being a c++ and embedded newbie I have put best of my efforts to develop the following codebase:
https://github.com/debojitk/WifiDoorLock
Details of the project are listed here:
https://hackaday.io/project/13478-smart ... -door-lock

Recently I started working on security implementation on the connections, so I tried to use Websockets library by Links2004, and used wss protocol. Now the problem is when I am using plain websocket (no ssl) the available memory is ~12kb. Whenever I change it to use wss the connection itself fails ad the esp restarts. The obvious reason being the wss implementation itself that uses WifiClientSecure api behind the scene. I tested with a sample sketch that every wss connection eats up up to 10-11kb memory. With 3 connections created I am left with 10kb memory.
So it is very obvious that using wss with my existing code will fail as is has got only 11 kb left.

Its a humble request to you all to have a look at my codebase ad suggest some fine tuning or design changes to optimize memory usage or any alternate way to implement security.

Thanks in advance.
Debojit

Hi debojitk,
it seems like You have almost every character array (aka string) in RAM - try to use F(""), FPSTR macros and strcmp_P functions... IMHO You have to study how to use PROGMEM for storing constants...

Pablo2048 wrote:Hi debojitk,
it seems like You have almost every character array (aka string) in RAM - try to use F(""), FPSTR macros and strcmp_P functions... IMHO You have to study how to use PROGMEM for storing constants...

Yes, that's true. But I am using debug switches, so, i will switch off those debug statements. that might save 4/5 kb. What are the other parts where I can save?
I have a commands array with the following definition:


I think this can go to PROGMEM. In such case should I use strcmp_P functions?

Your code is full with this unoptimized stuff like:
SD.remove("testsd.txt") -> SD.remove(F("testsd.txt"))
properties.put("mode","station") -> properties.put(F("mode"), F("station"))
...
For accessing strings in PROGMEM there are lot of articles / for example https://www.arduino.cc/en/Reference/PROGMEM