Ok, I was thinking that I could ask the state of the message S_LIGHT at every wake up, and if it changes, do my IR sending ... But it seems to not work. I guess for this, the problem is on the controller side, after send the command, without acknowledge , it give up and let the state of the button unchanged. Always on means power supply, This sensor must also get temperature, so I don't want to put it anywhere ... anyway thanks for you help :)