I would like to read signal from 3 wire hall efect speed sensor and two wire magnetic coil RPM sensor located in wehicle. Speed sensor is an active sensor (uses 12V power supply) and its output signal is digital, while RPM sensor is passive and its signal is AC in a range from 2 - 10 volts. I found some tips about CCP and ECCP and i think the best solution to measure speed and RPM from both sensors would be to use CCP in capture mode. PIC16F1827 offers three CCP modules, plus all three inputs are schmitt triggered so I think there shouldn't be a problem specialy for RPM sensor where signal is not digital.
Since output signal from the sensor is not TTL compatible (not in the 0-5V range) and because I don't want to influence on the C.D.I. readings (change the resistance of the sensor) I was thinking to use MOSFET over NPN. MOSFET as I know are voltage triggered rather than current so there shouldn't be any problems on the wehicle internal electronics.
To convert AC signal from RPM sensor I was thinking to introduce a rectifier diode.
Below is the wiring circuit for both sensors connected to PIC input. Tell me if my approach is correct or suggest me different one.
Since output signal from the sensor is not TTL compatible (not in the 0-5V range) and because I don't want to influence on the C.D.I. readings (change the resistance of the sensor) I was thinking to use MOSFET over NPN. MOSFET as I know are voltage triggered rather than current so there shouldn't be any problems on the wehicle internal electronics.
To convert AC signal from RPM sensor I was thinking to introduce a rectifier diode.
Below is the wiring circuit for both sensors connected to PIC input. Tell me if my approach is correct or suggest me different one.
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