Today it is time to etch the PCB circuits. The total PCB contains hall detectors, reflection detectors and an SPI input module for 24 high-speed digital inputs. Rotary encoders are made using dual hall detectors. The SPI module scans the inputs every 50 usec. This means that a 10 KHz signal can still be read. Or every pulse with a minimum of 50 usec pulse width.
Up to 12 high-speed rotary encoders can be processed simultaneously at speeds of up to approximately 10 KHz. My homemade encoders give 48 pulses per revolution. This corresponds to a speed of up to 12500 rpm.