Odd endstop behavior after several months of running fine


I am using a smoothie V1 to run the motors on a pick and place I built to pre-program Micro-controllers. It has been running great now for almost half a year. One day it started to a do thing when it homed the z axis it acted like the endstop stopped working because it would move up and just stall out. So I brought up the serial console and started playing around sending m119s, and sure enough Z min was a zero. I then verified all the other endstops by moving the gantry, and they reported properly, all of the sudden the Z stop reports properly. It will usually continue to work properly, and can be homed and run the machine, until I reset the board.

The first thing I tried was to put a multi meter on the headers giving the signal to the smoothie board, and that part was working properly. I then tried to update the firmware and start with a fresh config file, still nothing. I also blew out the board with compressed air, there was only a lit bit of dust on it that flew out.

I’m guessing the cortex on the board is flaking out? I cant find anyone else online that had this strange behaviour. I am tempted to just try hot air a new cortex chip on. Anyone have any ideas? Thanks in advance.

if you are sure it is onboard and not wiring, trace the endstop signal and retouch components with a soldering iron in case there’s a fractured joint. Look at the ground pin or just retouch the solder joint there too. Trace the Sig path all the way to the MPU.

then I’d try putting a 4.7K or 10K pullup on the Sig line.

Alright, I will try probing and touching up the signal paths. There is already a pull down on the head board on the gantry.

Thank you!

what endstops do you have? Endstops are recommended to be set for NC(normally closed(grounded)) and when triggered opened(sig goes high). So a pull-down would indicate something different since you wouldn’t expect there being any problem pulling a signal via a switch to ground.

The NC preference is because it means that an open/broken wire will open the endstop and stop the machine as opposed to the machine going to the endstop during a homing move and grind out a belt or break the machine with no endstop trigger sensed.

Basically, the head of the machine, along with the head board pcb is off of a quad 4c pick and place machine that we scrapped years ago. Which used optical sensors that source voltage. I didn’t change any of the sensors because it was such a nice package.

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I forgot to respond to this but basically, I ended up trying to use spare gpio pin header on the board, and after that it worked great… so idk