A while back I bought a superhet 433 Mhz transceiver/receiver pair (like this). The goal was to attach this simple device to a pi and control it using the great rpi-rf package. Unfortunately, it appears that my particular transceivers (one BY-305 controlling five blinds, one AC-123-06D controlling two blinds) emit codes that aren’t easily detected by rpi-rf.

Rather than try and get a PhD in reverse engineering the protocol (well, i did try for it but barely qualify for A.B.D) I found the life saving rpi-rfsniffer package. I noticed that if I simply did the following:

 rfsniffer --rxpin 7 record 2ndFloorS_All4_Up

This allowed me to override the default receive pin (which i had plugged into GPIO4). I then held down the “up” button on my 433Mhz remote. I repeated this procedure for the up and down on both remotes, giving each recording session an appropriate name. One note: I found that rfsniffer waited sometimes far too long to terminate the recording. To limit it I modified line 62 of /usr/local/lib/python3.7/dist-packages/rfsniffer.py as follows:

if len(capture) < 16000 and  GPIO.wait_for_edge(rx_pin, GPIO.BOTH, timeout=1000):

This limits the capture to 16000 samples (about 6 seconds or so.)

To play back the recordings I did the following:

rfsniffer --txpin 11 play 2ndFloorS_All4_Up

Again i overrode the tx pin as pin 11 (GPIO17) playing back the samples I had just recorded.

To integrate this into home assistant I simply used the excellent command_line integration. This was quick and easy and probably cannot be improved upon as there is no status coming from the blinds.

switch:
  - platform: command_line
    switches:
      blinds_2ndfloor:
        command_on: ssh -o StrictHostKeyChecking=no user1@<pi1_ip> '/home/user1/blinds_south_up.sh'
        command_off: ssh -o StrictHostKeyChecking=no user1@<pi1_ip> '/home/user1/blinds_south_down.sh'

This exposes a single entity, called ‘blinds_2ndfloor’ that has “on” and “off” buttons. The on script looks like this:

rfsniffer --txpin 11 play 2ndFloorN_Up
rfsniffer --txpin 11 play 2ndFloorN_Up
rfsniffer --txpin 11 play 2ndFloorN_Up
rfsniffer --txpin 11 play 2ndFloorS_All4_Up
rfsniffer --txpin 11 play 2ndFloorS_All4_Up
rfsniffer --txpin 11 play 2ndFloorS_All4_Up

The repetition seemed necessary, empirically, as sometimes a single blind would not start if only one or two playbacks were made. Additionally, since there is only one pi, i found putting all the command serially was better than letting HA possibly try to run the north and south transceivers in parallel. The script for off looks similar but, of course, plays back the “Down” samples.

With those scripts in place one can easily add HA automations to bring the blinds up or down based on the time of day. Eventually you need not touch anything in your house and can progress to a future of blissful automation taking care of everything and allowing us to evolve into our proper form:

Disclaimers:

• For docker-based HA: To enable ssh based remote invoke, one must ensure the /root/.ssh as a volume, then inside HA generate your ssh keypairs. Then add the HA pub key to your pi authorized_keys file.
• I totally realize this method of capturning the RF signals is suboptimal: in theory if you live in a busy RF environment you would be capturing, then playing back stray signals. The solution is obviously do your RF captures in your neighborhood anechoic chamber.