Other analog Scanning Z Probes?

gloomyandy

@qurt That's an interesting device, but I'm not sure the minimum range of 160mm makes it very suitable as a general 3d printer bed sensor. I also couldn't easily see what the actual electrical interface to the sensor was, do you have the details. Does it provide an analogue voltage (what range) that is proportional to the height? I doubt if anyone is going to implement some sort of "generic analogue probe interface" without having a particular probe in mind.

droftarts

@qurt If the output of the sensor is in the range 0 to 3.3V, or can be scaled to be this (using a simple voltage divider circuit), you can set it up as a probe or a sensor. I can't see or download the datasheet for the IL300 without creating an account to check the details, though.

See M558 and probe type 1 or 3 https://docs.duet3d.com/en/User_manual/Reference/Gcodes#m558-set-z-probe-type
You could set it up as sensor, rather than a probe, and used the 'linear-analog' sensor type; see https://docs.duet3d.com/en/User_manual/Reference/Gcodes#m308-set-or-report-sensor-parameters

Ian

gloomyandy

@droftarts Although you may be able to set up this sort of sensor as a type 1 or 3 probe, I don't think doing that will allow it to be used in scanning mode.

droftarts

@gloomyandy Ah, yes, true, I forgot the title of the thread! One for @dc42.

There was some talk of allowing the IR probe to be a scanning probe (though it would require a firmware change on the IR probe itself, which needs to be flashed using a programmer or Arduino), but David has had other development priorities.

Ian

qurt

Thank you.

@gloomyandy yes exactly - The request is to use it in scanning mode.

@droftarts I am a bit confused. Why do you need to flash the z-probe? What output do you need there? Shouldn't an anlog value be sufficient for the board to measure the bed in scanning mode.

droftarts

@qurt said in Other analog Scanning Z Probes?:

@droftarts I am a bit confused. Why do you need to flash the z-probe? What output do you need there? Shouldn't an anlog value be sufficient for the board to measure the bed in scanning mode.

I was talking about a specific probe that Duet3D produces, which needs a firmware update if it is to be used as a scanning probe. As to how a scanning probe works, @dc42 would have to explain what data format Duet boards expects. I would imagine that read latency is an issue, and that it involves tight timing between the probe and the mainboard.

Ian

qurt

@droftarts Do you need quicker cycletimes than 0.33 to 5ms?
And yes this is the entire purpose of this question.

SanderLPFRG

@droftarts Old topic, but I have another general analogue output probe (loadcell with op-amp structure and amplification with custom canBUS board)

I can configure and measure using the scanning Z probe (11) definition, but a load cell is unsuitable for a "scanning" measurement. It is however not possible to define it as a P1 probe on a canbus toolboard.

May I ask why this decision was made, and where in the firmware I could look to make it possible?

droftarts

@SanderLPFRG The wiki says here https://docs.duet3d.com/User_manual/RepRapFirmware/CAN_limitations#semi-permanent-limitations that it's technically possible to have other probe types beyond 8, 9 and 11. I think the concern is about latency, but @dc42 would know better, and be able to give you the advice on firmware.

Ian

SanderLPFRG

@droftarts I see.

I get why it would be a possible issue with latency but for our use we need to be able to define it as such.
We found in the source code where it defines the probe and throws an error, but we would like some advice on if just removing the error gives us a solution

dc42

@SanderLPFRG I think there are two pieces of work needed to support other types of scanning Z probe: (1) allowing general analog-output Z probes to be used in scanning mode; and (2) supporting analog Z probes over CAN.

SanderLPFRG

@dc42 said in Other analog Scanning Z Probes?:

Yeahh the biggest issue is that I do not want the loadcell configured as a scanning-type probe, but as a normal analog probe, which is prohibited for CANboards. so I am leaning to version 2.

I am trying to build new firmware for the 6HC (to remove the error it raises when remote Z probe type is not 8, 9 or 11) but I am getting building errors regarding the CoreN2G...

"../src/TinyUsbInterface.cpp:28:10: fatal error: tusb.h: No such file or directory"

SanderLPFRG

@dc42 please note that the tusb.h file is actually present

dc42

@SanderLPFRG looks like you are using the wrong tinyusb project. The one we use is called Libtinyusb.

SanderLPFRG

@dc42 I just tried to build with the latest master branch of the libtinyusb from here; https://github.com/Duet3D/LibTinyusb

I also tried the 3.6.0 beta2 release, which is the same as the rrf sourcecode I am trying to build

still did not work, same error

SanderLPFRG

@SanderLPFRG Got it working, version mismatch.

SanderLPFRG

@dc42 is it okay if I try to enable this functionality in a branch via github? If I manage I will make a pull request for you to integrate it into the main branches.

Lot to learn for myself, but I like a challenge.

dc42

@SanderLPFRG the firmware is open source so you can do what you like. There is already some support for analog probes in the expansion board firmware because the scanning inductive Z probe is in effect an analog probe.