Sensing a ground

[Wolf_Tm]

Hi,
is it possible for Analog CH1 (no pull-up) to sense when a wire goes to ground?
Or do I have to make a trick with a relay and send a 12v?
Thanks

[jrussell]

Please, never send 12v. These are 0-5v inputs, 12v would damage it.

Use a 2k to 10k resistor (value doesn't matter a lot, anything in there can work great) between the input and 5v and you're making your own pull-up. That's the best way. No need to get as complicated as a relay.

With the resistor in there as the pull-up, it will be up around 4-5v on the input when floating. If you ground the input, it will go to 0v, so you can set up a trigger for that action.

[Wolf_Tm]

Please, never send 12v. These are 0-5v inputs, 12v would damage it.

Use a 2k to 10k resistor (value doesn't matter a lot, anything in there can work great) between the input and 5v and you're making your own pull-up. That's the best way. No need to get as complicated as a relay.

With the resistor in there as the pull-up, it will be up around 4-5v on the input when floating. If you ground the input, it will go to 0v, so you can set up a trigger for that action.

Thanks Russell, I'll use an external pull-up.
Anyway I forgot to say I read on this ecu paper that its CH1 is the only one that can get 12v...

[fphil]

Of course this also depends on what is before the 0V wire, since it may never get to 0 any more with the pull up  ;)