I am working with the GPIO, successfully connected a couple things already. Now I have the following challenge when connecting a door bell to the GPIO:
- I can use the voltage that's going to the speaker
- at the speaker the voltage (vs ground) is 15,5V
- ringing the bell moves the voltage to 12,5V, i.e., there's ~3V over the speaker
- I want to use the GPIO input to detect this change
When I part the Voltage to ensure not to put more than 3,3V to the GPIO, the difference in Voltage is not big enough anymore to reliably detect the change as logical 0 / 1.
How can I best do this?
Thanks a lot for your help!