Reading weather sensor data to replace it through MQTT-to-433

[eyefly tinkerings]

Hi there!

I do have a projection clock from Oregon Scientific that is about 15-20 years old that does project outdoor temperature as well. Sadly the outdoor sensor broke - it still works, but the casing is broken.

I‘ve tried literally all available projection clock - none is as good as the old one.

So what i thought of was: Read the signal from the sensor using rtl_433 - then build something inside Home Assistant or similar where data is being send through a 433 transmitter.

Can the tool also encode instead of just decode?

Thanks in advance!

[Christian Z.]

rtl_433 is for receiving only. You'd need a sender like those very cheap superheterodyne sets and connect it to a pin on something like a Raspi or ESP32. You should be able to find some projects. A better option would be an I2C controlled sender like the CC1101 and similar. But there is even more programming involved. The actual protocol should be very simple though, just some OOK bits which can be send raw or encoded as PCM with the better options.

[Christian Z.]

Thanks a lot for your reply and hinting me in the right direction. I've found a lot of new information i need to process :-)
Just one for question: In what way is an I2C controlled sender better than the superheterodyne sets?

A complex I2C sender will offload the actual sending, you just push data bytes. They control the timing without interrupts or other jitter. And they have precise control over the frequency and other emission characteristics.

With just a "dumb" sender on a pin you'd need to control the pin to get the right timing. You have no control over the frequency and e.g. carrier width.