Detecting ignition on/off through GPIO in a 12V automotive scenario. What is the preferred way to drive the input, protecting it from getting fried by electrical disturbances at a budget?

[MikeMike]

Will a voltage divider and a Zener diode pretty much suffice or will galvanic separation be necessary? Does anyone know/have an out-of-the-box solution?

Thanks,

Mike

[gbm]

Single 220 kOhm series resistor should be enough.

[Javier1]

https://www.sunrom.com/p/tvs-diode-12v-bidirectional-smbj12ca-smb

check out TVS (Transient voltage supressor) diodes .

in automotive scenarios i always protect against 120V spikes from the battery (they do happen specially at motor startup/stall)

[Javier1]

*automotive scenario*