bluetooth rpm sensor for e-motive tach output?

[Geneman]

hello peeps, just asking the braintrust. i am trying to get a tach signal pulled off of the tach wire coming out of a tech3r electromotive ecu. the best would be if it were a bluetooth device , as i would like this device to talk to a dash mounted ipad mini running harrys laptimer! online you can find these devices which use the OBDII plug output to a bluetoooth device .. but i am surprised there are no other, non obd devices which would do this. any thoughts?

i might be asking way too much.. but what the hey..

thanks for looking..cheers

frank