IR Transmitter, not quite (hack)

[glmnet]

Hi there,

The idea is to easily hack Air Conditioner boards, so far I've been using an IR LED and a TSOP like IR Receiver inside or close to the device itself, the technique is used broadly, but I wanted to simplify it.

The original equipment IR Receiver is commonly pulled up NPN output so in theory I could just connect a GPIO to the same pin, here is the yaml:

remote_receiver:
  pin:
    number: D5
    inverted: True
    mode: OUTPUT_OPEN_DRAIN
  tolerance: 45%
  id: ir_receiver

remote_transmitter:
  carrier_duty_percent: 100%
  pin:
    number: D5
    inverted: true
    mode: OUTPUT_OPEN_DRAIN

climate:
  - platform: coolix
    sensor: temp_norte
    name: "${node_name} AC"
    supports_heat: True
    supports_cool: True
    receiver_id: ir_receiver

The interesting bit here is the remote_transmitter configuration:

1. Since we don't need to modulate the carrier, the duty percent is 100%
2. Output mode is OUTPUT_OPEN_DRAIN so we leave the external pull up (usually 5V) to pull up the signal, I measured with the scope and a simple OUTPUT mode will connect the output to 3.3V and the AC's controller will not pick up the signal.
3. Inverted! yes, as we are now providing the signal to the IC directly and not the LED.

Also remote_receiver is configured as OUTPUT_OPEN_DRAIN, this works as there is likely an external pull up resistor on the AC's board, and being open drain means we are not giving a path to ground.

Together with a bme280 temp sensor you can DIY hack an AC's very easily and quickly and so cheap.

Tested with esphome 1.21.0 dev

[muxa]

Interesting idea! I'm trying to do something similar, but I have ability to "inject" my MCU between the IR receiver and the AC. The challenge that I'm facing is IR data "forwarding" to the AC is not working.

Your approach seems more straight forward and will ensure that the AC can be controlled by the IR regardless of the MCU status (whereas my approach relies on the MCU to forward IR commands to the AC).

Is there no feedback from remote_transmitter to remote_receiver when sending commands from MCU?

[glmnet]

no, it's not a man in the middle approach, is more like an observer and intruder thing. Good thing is it should still work if ESPHome goes bad unless it goes really bad ;)

[muxa]

@glmnet Since receiver and transmitter are both connected to the same pin, when the transmitter sends data the receiver will receive the same data, so there will be a feedback loop. Does that cause any issues with the climate component? I.e. when the cover sends the data (from HA for instance), it will also receive the same data back.

[glmnet]

No feedback loop because when the esp8266 transmits it disables interrupts (hence disables receiving)

I'm not sure on the esp32

[paulsteigel]

Hi,
I applied your approach on a Lg AC and I can control the AC with HA and climate update state correctly. However, when I use the remote control to set temp of the AC, climate does not update the new state (i.e new temp) on Home assistant.
How can i deal with this?
Best1

[muxa]

I have tested your idea on an ESP8266 connected to the IR module from Daikin FTXS60LVMA without connecting to the AC first.
Looking at the oscilloscope it worked! The HA climate component did not not seem to have any issues with the feedback it's getting when transmitting the data.

I then connected this to the AC and it also worked! I could control the AC with the IR remote, the state was applied to the climate in HA and I could control the AC from HA. Awesome!

I thing I am a bit worried about is the fact that the input pin the AC board for the IR signal outputs 5V, which is connected to one of the ESP pins, which are designed for 3.3V. @glmnet, do you have any insight into if this might cause any issues long term?

[glmnet]

https://www.google.com.ar/amp/s/ba0sh1.com/2016/08/03/is-esp8266-io-really-5v-tolerant/amp/

[muxa]

@glmnet
Cool, I have found another confirmations of 5V tolarance:

According to the CEO of Espressif, Teo Swee Ann, the I/O pins of the ESP8266 are 5V tolerant: https://hackaday.com/2016/07/28/ask-hackaday-is-the-esp8266-5v-tolerant/#comment-3122361

I've been using your solution for a few days now with no problems. I hope it remains that way :)

Thanks for the idea!

[phankhanhpvk]

I use an LG air conditioner and I'm having trouble receiving infrared signals from the remote control. The LG infrared code is not detected in the log dump.

  pin:
    number: D5
    inverted: True
    mode: OUTPUT_OPEN_DRAIN
  dump:
    - lg
    - raw
  tolerance: 70%
  id: ir_receiver```
  
  dump log
```[15:51:41][D][remote.raw:028]: Received Raw: 3356, -9823, 545, -1538, 541, -491, 549, -483, 547, -485, 544, -1528, 542, -506, 544, -503, 551, -481, 545, -487, 542, -489, 552, -480, 517, -515, 546, -1518, 543, -489, 518, -521, 550, -483, 546, -1517, 546, -486, 540, -1524, 545, -494, 
[15:51:41][D][remote.raw:041]:   546, -486, 543, -489, 541, -491, 518, -515, 545, -486, 545, -490, 538, -1522, 548, -493, 547
[15:51:42][D][remote.raw:028]: Received Raw: 3172, -9840, 537, -1554, 548, -484, 513, -519, 541, -491, 518, -1554, 515, -517, 513, -519, 542, -490, 518, -513, 548, -484, 514, -519, 542, -505, 545, -1527, 523, -517, 521, -512, 518, -512, 517, -1547, 543, -489, 541, -1531, 548, -1531, 
[15:51:42][D][remote.raw:041]:   549, -492, 548, -491, 518, -514, 546, -486, 544, -490, 539, -491, 519, -1555, 544, -1525, 546
[15:51:51][D][remote.raw:028]: Received Raw: 3174, -9826, 541, -1557, 543, -497, 522, -518, 522, -510, 520, -1543, 516, -516, 513, -519, 521, -511, 522, -510, 516, -515, 514, -519, 522, -518, 542, -1521, 517, -522, 518, -1546, 544, -1528, 524, -515, 521, -511, 520, -1544, 513, -533, 
[15:51:51][D][remote.raw:041]:   507, -535, 515, -1548, 522, -510, 540, -1524, 514, -517, 544, -491, 517, -1552, 517, -514, 547
[15:51:51][D][remote.raw:028]: Received Raw: 3177, -9861, 538, -1546, 523, -517, 512, -532, 508, -520, 520, -1543, 516, -516, 544, -488, 521, -511, 518, -514, 516, -515, 545, -488, 521, -518, 522, -1542, 517, -523, 517, -515, 546, -1517, 572, -1500, 549, -491, 549, -483, 515, -1557, 
[15:51:51][D][remote.raw:041]:   512, -527, 513, -519, 542, -500, 508, -514, 547, -485, 513, -520, 541, -1529, 519, -513, 548```

[glmnet]

it's not gonna work that way, dump does not work for climate ir, the lg there is a single remote control which usually are short numeric codes used in e.g. tv sets, you'll see the info for lg codes here: https://esphome.io/components/remote_receiver.html

in the other hand if you have an LG air conditioner unit you'll need to figure out which code it is using, the esphome have a few implemented but you have to use this https://esphome.io/components/climate/climate_ir.html

There is a climate_ir_lg platform for climate, but sometimes the protocol does not match the manufacturer.

[trip5]

I'm gonna jump in here because my workplace has LG Air conditioners. They use LG2 codes which isn't available in ESPHome... but I was able to use a Tasmota-flashed IR Receiver to extract Hex codes that ESPHome can send as such:

        - remote_transmitter.transmit_lg:
            data: 0x880095E # cool 24

[pana800]

Hi, I had the similar issue with LG and I tried to add the 'header_high: 3265us' and 'header_low: 9856us' to the climate component.
The receiver could sync now.
Currently it looks like the LG platform is still not perfect (for my case) as it doesn't support FAN ONLY mode and SWING function.

[Rjevski]

Has anyone got this to work on ESP32? Trying this and it seems like the pin stops being open-drain after the first IR transmission (more specifically, after the RMT channel has been set up).

I've opened an issue on the feature requests tracker to see whether this "hack" is something the project wants to support officially and whether my issue warrants a proper bug on the main tracker.

[paulsteigel]

Hi, I tried the approach, and esp8266 can control the AC (LG brand) however, the it does not sync with the IC remote controller. I used the remote controller to set the AC to 24 degree Celsius, cool mode, AC worked as expected but that information does not show on HA.
Can you advise? I copied your yaml code and flash to NodeMCU.
Best!

[trip5]

There's nothing you can do about this. If you wish HA to always be in sync with what the AC is doing, you can only use the ESP and HA to control the AC.

I do realize the AC is also sending out a code, I also can see from the raw display output from an IR Receiver that my AC is constantly broadcasting something about its status. But there's no way to read this.

Heck, it's actually very easy to make your LG AC controller out-of-sync too. Just cover the IR while changing the temp from 25 to 24... and the remote control doesn't know the AC never changed to 24. Whatever the AC is broadcasting, the remote doesn't understand it either...

[Rjevski]

The IR climate component does support attaching an IR receiver which would then receive commands from the original remote (just like the aircon itself) and update its internal state based on it.

This very thread is about a "hack" where you use the same pin to both read IR traffic from the aircon's own IR transceiver line as well as inject traffic.

@paulsteigel can you try with an external transmitter & receiver first? I suspect there might have been a regression where this hack of using the same pin for both transmit & receive is no longer working and leads to undefined behavior.

[paulsteigel]

Hi All,
The I understood your sharing, however, with the following code, a friend of mine have my problem done:

remote_receiver:
  pin:
    number: GPIO14
    allow_other_uses: True
    inverted: True
    mode: OUTPUT_OPEN_DRAIN
  tolerance: 45%
  id: ir_receiver

remote_transmitter:
  carrier_duty_percent: 100%
  pin:
    number: GPIO14
    allow_other_uses: True
    inverted: true
    mode: OUTPUT_OPEN_DRAIN

climate:
  - platform: climate_ir_lg
    sensor: current_temperature
    name: "Sleeping room AC"
    header_high: 3265us # AC Units from LG in Brazil, for example use these timings
    header_low: 9856us
    receiver_id: ir_receiver    
sensor:
  - platform: homeassistant
    id: current_temperature
    entity_id: weather.forecast_house
    attribute: Temperature

And this also worked with universal remote control.
Before having this, I tried with adding a lambda call on climate to inform receiver on this call and when remote control send a command it can rely on it to inform climate to update the status of the AC.
But my friend work with just 2 news command:

header_high: 3265us # AC Units from LG in Brazil, for example use these timings
header_low: 9856us

And all solved!
Best!

[trip5]

Sorry I may have jumped to a conclusion with my reply... especially I assumed @paulsteigel was using LG codes on an LG2 code AC. My experience so far is mostly with LG2 codes and a few that can only do raw data. LG2 is somewhat supported by LG codes but lacks a lot of commands... and perhaps I haven't kept up to date anyways.

[paulsteigel]

Many thanks to trip5 for your information!