Updating ESPHome NEC Remote Transmitter hex for v2021.12

Get your IR devices working again

After I updated to a more recent version of ESPHome and flashed my fan controller, it stopped being able to control the fan. After a bit of troubleshooting and searching, I found the culprit.

Note
In version 2021.12, the order of transferring bits was corrected from MSB to LSB in accordance with the NEC standard. Therefore, if the the configuration file has come from an earlier version of ESPhome, it is necessary to reverse the order of the address and command bits when moving to 2021.12 or above. For example, address: 0x84ED, command: 0x13EC becomes 0xB721 and 0x37C8 respectively.
Remote transmitter docs

Clearly, I don’t read all of the release notes…

So after reading this, I was confused. And if you’re here, you are probably confused. So here’s what I did to solve it. In my case, I used the python3 command line inside of my ESPHome docker container, but this should work anywhere you have python3 installed.

Steps for updaing the address and command values

CLI into container
Type python3
Type bin(<value>) and replace value with the hex or decimal value.
Reverse this value right to left: abc becomes cba, the 0b stays at the front.
Count the number of digits, if it’s less than 16 digits, add zero’s at the end to make it 16 digits
Type hex(0b<value>) and replace value with the reversed binary.
Resulting hex should work as your command.

Example

Below are the steps I used to convert my Fan Oscillation values:

- platform: template
  name: Fan Oscillation
  turn_on_action:
    remote_transmitter.transmit_nec:
      address: 255
      command: 25245

- platform: template

name: Fan Oscillation

turn_on_action:

remote_transmitter.transmit_nec:

address: 255

command: 25245

root@cbd65cf7857e:/config# python3
Python 3.9.2 (default, Feb 28 2021, 17:03:44) 
[GCC 10.2.1 20210110] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> bin(255)
'0b11111111'
>>> # 11111111 reversed is 11111111
>>> # 11111111 is 8 digits, so add eight zeros to the end = 1111111100000000
>>> hex(0b1111111100000000)
'0xff00'
>>> 
>>> 
>>> 
>>> 
>>> bin(25245)
'0b110001010011101'
>>> # 110001010011101 reversed is 101110010100011
>>> # 101110010100011 is 15 digits, so add one zero to the end = 1011100101000110
>>> hex(0b1011100101000110)
'0xb946'

root@cbd65cf7857e:/config# python3

Python 3.9.2 (default, Feb 28 2021, 17:03:44)

[GCC 10.2.1 20210110] on linux

Type "help", "copyright", "credits" or "license" for more information.

>>> bin(255)

'0b11111111'

>>> # 11111111 reversed is 11111111

>>> # 11111111 is 8 digits, so add eight zeros to the end = 1111111100000000

>>> hex(0b1111111100000000)

'0xff00'

>>>

>>> bin(25245)

'0b110001010011101'

>>> # 110001010011101 reversed is 101110010100011

>>> # 101110010100011 is 15 digits, so add one zero to the end = 1011100101000110

>>> hex(0b1011100101000110)

'0xb946'

So the new command is:

- platform: template
  name: Fan Oscillation
  turn_on_action:
    remote_transmitter.transmit_nec:
      address: 0xFF00
      command: 0xB946