@dbemowsk Thank you for all that info, it's giving me a great start in the right direction. Sorry it's taken me so long to respond to the questions you had for me.

So what I have since found out is that Homeseer has two separate plugins, one for Arduino and one for mysensors.org. I had no idea there was a difference but have learned that mysensors uses a different library. I'm not sure if the MySensors plugin on this site that you mentioned is the one that I would use with Homeseer or not. Guessing that I will just stick with the one from the Homeseer forum.

So I didn't realize this when I started, but it's sounding like if I use the Arduino library and the MySensors library I would have to have a gateway for each? Hoping I won't have a need to do that... If I use the MySensors gateway, from what I understand the MySensors gateway is only supported as a serial interface, so if I have questions I'll let you know, thank you for that!

On my project, I would like to control the speed as well as the on/off for fan and light, is that not possible? I have a button for each speed (High/Med/Low/Rev), a button for fan on & a button for fan off. The light has a rocker, if you push up it turns the upper light on/off and lower for the lower light on/off. Would I need a relay for each button? (Eight relays?) Might be easier to do it the way you are doing it, just don't have that level of electronics experience yet.

How is your project going by the way? Didn't mean to step in the middle of your thread with all my noob questions.

@dbemowsk Unfortunately this will be my first project with arduino so I won't have the electronics knowledge yet to attempt pulling our ceiling fan apart. Might upset the wife when I can't get it back together...

I have my first arduino uno r3 kit on it's way, do you have any suggestions about which parts/relays to use for my project? If there are smaller parts to help make it less bulky I would be interested in getting those instead. The goal is to use my HA (Homeseer with Arduino plugin) to control the ceiling fan (on/off, speed & Light). So I'm guessing I would need a wifi shield, the R3 and relays?

For the code, is there a good project you suggest I study that would help me accomplish what I would need to get started with hacking the remote?

My hope is to eventually get to the point where I can implement a cleaner solution like you are doing...but in the meantime I will have to settle with the easier solution. Thank you so much for any help!

@micah Hi, I'm new to this forum and Arduino and have been looking for a way to control my RF controlled ceiling fans with my HA system. I have both Hunter and Hamilton Bay ceiling fans that each work on their own RF frequencies, however they do not use a fan controller like dbemowsk example above. I was thinking that simulating a button press from the Arduino would work perfectly. I have an extra remote that it could connect to and then just place it in the room. We could use the other remote if we want to manually adjust or turn it on.
Would you mind posting a parts list and how you accomplished your project when you are done? Really looking forward to getting this incorporated into our HA system!
Thank you!