Simple cable tester for checking CAT network cables. It can check wiring issues as well as cable length.
Wiring mismatch testing is based on voltage division.
Cable length measurement is based on signal reflection.
The microcontroller is a PIC18F45k50. This model is used because it has a CTMU unit that enables the microcontroller to measure nanosecond short times which is required for cable length measurement. The C program was written in MPLAB IDE.
The SMD circuit was designed in Eagle CAD circuit designer. The PCB is double-layered. Future plan is to add another comparator and make cable length measurement on all 4 pairs.
Master circuit schematic:
Remote circuit schematic:
