yet-another-intercom-hack

Hi everyone !

The following thread is about hacking an intercom .. using an Espruino Pico
( aka "yet another iteration on the Intercom Hacks for the HaD readers .. ;p )

Simplest functionality planned:

• watches ringer and look for codes/patterns
  
• trigger relay
  
• play sound from SD card
  
  

Further mods:

• replace original ringers beep-that-makes-my-ears-puke by a sweet-sweeet melody
  
• add ESP8266 to trigger a notification on my laptop
  
• add hacked GSM / GSM shield to send text messages
  
  
  

Now, this project is huge wip, considering the code parts are yet-to-be-merged, and that the actual circuit is being tested with various components ( if can do, less bulky ones, ex: replacements for the current relay .. )

The project can be tought as three main parts:

1: morse-like codes/patterns matching:
Handling this was quite easy, since the code needed for that had been provided in the "SINGLE BUTTON COMBINATION LOCK" tutorial ( Single Button Combination Lock ), although, the "NEXT STEPS" 'd have been controlling a relay in my case, not a lock ( no real difference at this abstraction level ;p ).
Last but not least, as I wanted to be able to handle multiple codes that could share same beginning codes/patterns while still being able to vary in length, I ended up writing my "1st next step" from the original code, behaving as exposed + handling an "inactivity timeout" ( & some more things to come maybe ? .. ), which is hosted at the following url:
Single Button Combination Multicodes Lock

2: playing audio from an SD card to the original mic line:
Thanks to studying my intercom, the other Intercom hackers notes & having nice answers from +Gordon, this part is almost done, but still needs some code cleaning/optim not to take up too much memory on the Pico

3: triggering the "AP" ( ground floor door lock ) & listening to the "CA" ( ground floor call in ):
After identifying the purpose of each wire/line, it's pretty easy to deduce how to trigger the said-"AP" ( by shorting the line which has the highest voltage present to the Gnd one ), and how to listen to the ringer/bell ( needs a cap to keep DC only & few discrete components to lower/clamp the voltage to an acceptable "digital 1", aka min 2V, max 3.3V )

Nb: if some stuff's not here [ yet ?], it may be there:
https://123d.circuits.io/circuits/117671­0-yet-another-intercom-hack