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Ideas needed to protect hall sensors and encoder outputs.
Hey guys I could use some ideas on this. The Prop main board has various RJ 45 ports that connect to different input sources. I like cat5 cable because installers can make up cables and it is a nice method of connecting remove devices. There is a brushless DC motor that has an encoder
and hall sensors
The encoder output is totem pole. The hall sensor output is open collector, the BLDC driver board provides 6.35V via pullups to the hall sensor outputs.
In the photo and schematic, the motor has a PCB that mounts on it that has an RJ45 that connects the motor back to the Prop main board. On the Prop main board, there are 7 other Rj45 ports for connecting other devices, and all off them vary in terms of pinout and 5v and GND will be on different pins for different ports. All the ports contain 5v, GND, and signals, and I used different pin arrangements to try to reduce noise by arranging twisted pairs on the cat5 in certain ways based on what what on that port. Unfortunately this has caused occasional problems due to people not reading the warning sticker on the motor port that says damage may occur to the motor if the cable is plugged into the wrong port! It is rare but sometimes they plug the cable in the wrong port and kill the encoder or a hall sensor. One example of a wrong port could put 5v and GND on the encoder outputs A and B.
One trick I added to the motor breakout board was 100ohm's in series with the 3 hall sensors and the 2 encoders. I think this reduced some failures but still I get a rare failure and want to try to remake the motor breakout PCB with some better protection. It is too late to change the main board pinouts. Does anyone have any ideas I could try on these signal lines ie diodes etc?