PIC16F628 as digital Tachometer

Posted on May 24, 2012

Pin 3 defines the Display type: Common Cathode or Common Anode. Connect this pin to GROUND if you are using common cathode 7-segment led displays. To use common anode displays, connect it to VCC (positive) Pin 4 is the signal input, you can use optical sensors (Fototransistors, fotoresistors, etc), magnetic sensors (Hall effect, reed switch, etc) or using a switch. Unfortunately, I have no idea how to connect this circuit to a vehicle. If you want to share details about how to attach this circuit to an automovile, I will post this information.

PIC16F628 as digital Tachometer
Click here to download the full size of the above Circuit.

DO NOT CONNECT ANY SIGNAL DIRECTLY TO PIN 4. High voltages can damage the PIC. If the input signal is more than 5 Volts, Use a driver as TTL, CMOS, Amp Operational or Transistors. NOTE: Use only 10Mhz xtal and 22pf or 33pf capacitors. The RPM are displayed as units, that means, the RPM indicated in the display is the actual reading from the input pin. This version have a faster sample rate so the reading is constantly updated, you get a faster reading that the previous version.

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