HD8: OnBoard Counter type B

The board incorporates an onboard counter type B (called OBCB). This is a medium speed Firmware counter that can be used for frequency or totalized counting. Typical applications include mains (line voltage) frequency measurement, engine RPM, belt speed (using a pulse encoder) or wind speed using a rotating vane anemometer.

The OBCB exists on several SPLat boards. Generic documentation for the feature is provided in the OnBoard Counter type B guide.

The OBCB is implemented on inputs 0 though 3. The maximum count frequency is approximately 1.8kHz, assuming a perfect square wave input. The accuracy is approximately 2% (this varies from product to product, depending on whether they use a crystal for timing or not. This board does not have a crystal).