HVAC zoned ducts (dampers) automation

Hardware
1

I am trying to automate my ducted hvac. we currently have an interface on the wall which uses a small push button and an led to indicate weather the particular zone is on. I opened it and did some probing. Figured that all we need to do is, just short the switch button (5v) with ground for few milli seconds to toggle it. I have soldered all the additional wires and now I need to figure how to actually short them.

The 4 wires you see in the pic are 5v wires for 4 toggles (4 zones). I just need to short them with ground (for which I have soldered another wire as well) to toggle the damper on/off for few milli secs. Is it possible to do it using d1 mini (I have a few of them) using esphome? if not what is the best way to achieve this? thanks for checking.

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3

any particular reason you withdrawn your post? that looked like the most complete answer for question ever posted on any forum. Thanks a lot for that.

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4

Yeah I forgot that the open drain outputs of the ESP boards are not technically 5V tolerant and I don’t have time right now to explain how to construct open collector transistor drivers.

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5

no problem. please do explain when you can. Thanks.

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6

Also I am not too sure, if it is 5v. I will check and if it is 3.3v or less I will go ahead and try your earlier suggestion. Thanks.

7

Ok, I managed to figure this. I have connected the 5v (4x from the duct control unit) to GPIO pins directly on my d1 mini. so far it is working fine. if it burns out, I will put a 3.3v logic shifter in front of each pins. But since the open_drain seems to be floating the pins while off, hope this works with out any surprises.

I am pasting the config below for posterity. I have ordered a few photoresisters (to know the state of the switch) now and will have to find a way to accomodate them as well. I probably may have to move all this setup to a nodemcu for the sake of additional pins.

esphome:
  name: ducted_dampers
  platform: ESP8266
  board: d1_mini

wifi:
  ssid: "xxxxx"
  password: "xxxxxxxx"

# Enable logging
logger:

# Enable Home Assistant API
api:

ota:
      
switch:
  - platform: gpio
    pin:
      number: D2
      mode: OUTPUT_OPEN_DRAIN
    id: damper1
    inverted: yes
  - platform: gpio
    pin:
      number: D5
      mode: OUTPUT_OPEN_DRAIN
    id: damper2
    inverted: yes
  - platform: gpio
    pin:
      number: D6
      mode: OUTPUT_OPEN_DRAIN
    id: damper3
    inverted: yes
  - platform: gpio
    pin:
      number: D7
      mode: OUTPUT_OPEN_DRAIN
    id: damper4
    inverted: yes
  - platform: template
    name: "lounge damper"
    turn_on_action:
    - switch.turn_on: damper1
    - delay: 200ms
    - switch.turn_off: damper1
  - platform: template
    name: "bedroom damper"
    turn_on_action:
    - switch.turn_on: damper2
    - delay: 200ms
    - switch.turn_off: damper2
  - platform: template
    name: "rishiroom damper"
    turn_on_action:
    - switch.turn_on: damper3
    - delay: 200ms
    - switch.turn_off: damper3
  - platform: template
    name: "guest damper"
    turn_on_action:
    - switch.turn_on: damper4
    - delay: 200ms
    - switch.turn_off: damper4
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