BL Touch Self Test Speratic

droftarts

@dc42 runs a BLTouch on a toolboard in his setup, and as far as I know hasn't had these problems. How are your electronics set up? Is the Duet powering a RPi, with peripherals (eg screen)? Any other boards or sources of power drain/interruption on the 5V power? Can you put a scope on the 5V at the tool board, and see if the voltage is being pulled down?

@dc42 also suggests: "It would be helpful if some one could test whether putting additional capacitance e.g. 100uF between +5V and GND solves it."

Ian

oozeBot

Here is a picture of my electronics.. using a350w Meanwell power supply, Duet 3, RPI4, tool distribution board, and the toolboard is mounted to the tool head.

Unfortunately, I don't have access to a scope, nor do I have any 100uf capacitors, but can order some if there is a strong desire to learn if this corrects the issue.

Eduma

@fcwilt @I_Jedi @oozeBot

I had found that after machine power up the bl touch would immediately run its self test and begin to flash. If I disconnected power to the bl touch then reconnect it would run its self test and complete the test without issue. This worked 100% of the time. This lead me to connect a scope my cheap 24v to 5V power converter and found that the 5V was a gradual increase instead of an instant on.

I tried utilizing the reset command but did not have consistent luck. I believe that reset is only intended for probe up/down failures, not power alarms. Would be great if BL touch offered an up/down/error outputs. Would also be nice if you could actual see the blue indicator light.

oozeBot

Got a new battery for my multimeter and confirmed it's reading right at 5v. I powered down, plugged back in after 10 seconds, and it immediately read 5v. There is nothing else connected to the toolboard's 5v rail.

As stated, it has never done a self-test at startup. After rebooting, it glows steady red (with the occasional blink). M401 works. M402 works but the probe immediately begins flashing red. It is doing this on two brand new BL Touch v3.1 probes.

Again, it is working even in this error state of flashing red, but something is still obviously wrong. At this point, I'd love someone to call me out on some glaring error I should have caught, but I don't know what else could be wrong. The relevant lines are below. Toolboard is on B20. I've tried both with and without the ^ with the same results.

M950 S0 C"20.io0.out"
M558 K0 P9 C"^20.io0.in" H5 F120 T10000 A5 R0.1 S0.01

I_Jedi

@droftarts Thanks for sharing the word from the experts -- I have an extra 120uF from grounding the second twisted pair in the ADSL line. I dont know enough about resisters to know if that is close enough value, but will give it a go. Does direction of the resister matter? For what its worth, I am powering rPI and a 7" screen off of the Duet3 board.

I_Jedi

@Eduma interesting. I have no red alarms at power on and the BLTouch seems to be working correctly at startup (M280 commands all work without need to force alarm reset). I just dont get the poweron automatic self-test... that's it as far as my issues. Genuine v3.1 for what its worth.

oozeBot

Please look at my post linked below to see if this helps you out as well. Thanks

https://forum.duet3d.com/topic/18261/bltouch-v3-1-toolboard-resolution