Changes to work with my version of the Hampton Bay remote

[Concours99]

Thank you for the implementation on how to control a Hampton Bay fan via MQTT from my Home Assistant.

Unfortunately, it was not a turn-key solution. I discovered that my remote sends a checksum in addition to the data that you decoded. Without the checksum, the controller in the fan ignores the signal.

This is what my remote looks like:

Differences in the code sent -

You documented the code sent as follows: 000xxxx000000yzz00000

Where:

• xxxx is a value that is a computation from the DIP switches in the remote
• y is light on/off
• zz is fan speed

What I have determined for my remote is similar: 000xxxxaaaaaaazzbbbbb

Where:

• xxxx is as you described
• aaaaaaa is a value that indicates the percentage the light is on. I haven't decoded all the possible values for this, but 0000001 and 0000000 are on and off, respectively. So your method does work for an "100% on" / off implementation.
• zz is as you described
• bbbbb is a checksum. It is calculated by adding each of the 4-bit chunks the precede it (16-bits in all) and putting the remainder in these bits.

Here is the function that I wrote to implement it:

int calculateChecksum(int number) {
  int sum = 0;

  while (number > 0) {
    sum += number & 0xF;
    number >>= 4;
  }

  return sum % 16;
}

and I changed the code to complete the rfCode to:

 int rfCode = dipToRfIds[fanId] << 9 | fans[fanId].lightState << 2 | fanRf;
 rfCode = rfCode << 5 | calculateChecksum(rfCode);

so it calculates the left-most 16 bits, sends them to the checksum procedure and then constructs the entire 21-bit message to send.

Thanks again for your work. Hopefully my additional insights will help others with their own implementation.

BTW, the frequency for my remote is 303.85 which I found by searching the FCC site for the number indicated on the back of the remote:

https://fcc.report/FCC-ID/CHQ8BT7096T/

[patrickdk77]

I'll look at adding this, but yes, there is an unlimited different versions of hampton bay codes, as they keep expanding it, and they are just rebranding china ones these days. ideally though I would like to name them after the encoding chip used, but that is more impossible for people to find out.

[Concours99]

FWIW, my fan and remote are both quite old.

[patrickdk77]

Yep, definition of old, I was meaning 80s :)