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    Connecting and reading a pulse generating encoder

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    • pfnundefined
      pfn @oc_geek
      last edited by

      @oc_geek the output signal pin from the TCRT5000 would go into any of the ioN.in pins

      Configure the pin as appropriate with
      M950 J0 C"ioN.in"
      M581 P0 T0 ...

      Create /sys/trigger0.g and add code in there to do whatever is needed.

      I haven't tried putting together an ercf yet, but it's on my list of things to investigate.

      oc_geekundefined 1 Reply Last reply Reply Quote 1
      • oc_geekundefined
        oc_geek @T3P3Tony
        last edited by oc_geek

        @t3p3tony Hi Tony, thanks for coming by

        I have to confess i'm totally ignorant. I'm just trying to figure out if there is a way for RRF to use the Enraged Rabbit MMU 1.1 (Voron)

        The pulse sensor is a TCRT5000 (IR Infrared)

        TCRT5000 infrared reflective sensor
        Detects the reflected distance: 1mm ~ 25mm Applicable
        The working voltage: 5V
        The output format: digital signal (0 and 1)

        I suppose it just sends digital 0 or 1 (without a specific protocol)

        d69bf68a-6024-47e5-aa71-575a2613cf3e-image.png

        Any advice help is very much appreciated in advance

        46ae3ca1-dea6-4b97-8de2-5c90e26e7a01-image.png

        1 Reply Last reply Reply Quote 0
        • oc_geekundefined
          oc_geek @pfn
          last edited by oc_geek

          @pfn
          Thanks for the explanation.

          I realize just now that this is the same "trick" i use for the filament sensor which is on my Mini5+ while i use the 1LC as tool board. Makes sence

          That way you basically invoke the trigger and add 1 to the counter. Good idea. I hope it can stand the 500 Hz rate though... @T3P3Tony (do you know ?)

          So couple of macros (count and reset) and we shall be in the game

          I'm at the same stage of yours atm.
          I have bought some of the key parts but have not yet printed it.
          I hope we RRF folks are in the game too 🙂

          T3P3Tonyundefined pfnundefined 3 Replies Last reply Reply Quote 0
          • T3P3Tonyundefined
            T3P3Tony administrators @oc_geek
            last edited by

            @oc_geek so this is generating pulses at 500hz? There must be more too it if there is a pulse counter on the unit itself.

            www.duet3d.com

            1 Reply Last reply Reply Quote 0
            • pfnundefined
              pfn @oc_geek
              last edited by

              @oc_geek 500Hz rate? why is it so high? It should only trigger once per unit distance (which shouldn't be much lower than about 1mm per pulse...)

              1 Reply Last reply Reply Quote 0
              • T3P3Tonyundefined
                T3P3Tony administrators @oc_geek
                last edited by

                @oc_geek yeah the TCRT5000 is a reflective optical switch or potentially a distance sensor depending on how it was used. is there a rotating element with slots in?

                www.duet3d.com

                oc_geekundefined 1 Reply Last reply Reply Quote 0
                • o_lampeundefined
                  o_lampe
                  last edited by

                  @oc_geek you could use a frequency divider to reduce pulse count/second . They will reduce by 2,4,8 a.s.f. depending on their setting.
                  A small ATtiny or PIC processor can do the trick, too.
                  Then, when Duet gets triggered , add 2,4,8 pulses to the equation instead of 1.

                  In any case make sure, the pulse counting macro is as short as possible. Otherwise you might miss incoming pulses.
                  Write another macro to read the global pulsecounter and go on from there.

                  1 Reply Last reply Reply Quote 1
                  • oc_geekundefined
                    oc_geek @T3P3Tony
                    last edited by

                    @t3p3tony as far as i could see from the Discord ERCF 1.1 discussion it reads a Bondtech gear which rotates with filament
                    Filament running at 20 mm / sec so that's where the 200 - 500 Hz comes from (i'm just reporting what i was told)

                    T3P3Tonyundefined 1 Reply Last reply Reply Quote 0
                    • T3P3Tonyundefined
                      T3P3Tony administrators @oc_geek
                      last edited by

                      @oc_geek so whats the pulses/mm of this sensing arrangement. There is existing code for using a pulse based filament monitor
                      https://duet3d.dozuki.com/Wiki/M591#Section_M591_RepRapFirmware_Num_3

                      Type 7

                      www.duet3d.com

                      oc_geekundefined 1 Reply Last reply Reply Quote 0
                      • dc42undefined
                        dc42 administrators @oc_geek
                        last edited by

                        @oc_geek what's the purpose of measuring the counts? Is it to detect if the mechanism is jammed?

                        With a simple pulse generating encoder, you will not be able to determine in which direction the mechanism is moving. Might that be a problem?

                        Duet WiFi hardware designer and firmware engineer
                        Please do not ask me for Duet support via PM or email, use the forum
                        http://www.escher3d.com, https://miscsolutions.wordpress.com

                        oc_geekundefined 1 Reply Last reply Reply Quote 0
                        • oc_geekundefined
                          oc_geek @dc42
                          last edited by oc_geek

                          @dc42 i understood they use it to determine the filament position (real travel distance) when loading a specific filament in the MMU down to the tool head
                          With the encoder they say it is possible to meisure with a precision of 1 mm
                          Direction is derived by other means and hold by other variables

                          All that said would it be possible to use triggers to follow it up @ e.g. 250 Hz ?

                          pfnundefined 1 Reply Last reply Reply Quote 0
                          • oc_geekundefined
                            oc_geek @T3P3Tony
                            last edited by

                            @t3p3tony i saw that but it wont be possible to inquire the position nor to reset it (unless i'm reading it wrong)

                            1 Reply Last reply Reply Quote 0
                            • Dan1990undefined
                              Dan1990
                              last edited by Dan1990

                              The Klipper firmware seems to work fine with the ERCF, so perhaps will be valuable to check their code? It wIll gives more understanding towards what oc'geek and many others trying to get. (The voron - duet community is big )

                              That is the link to the PCB for ERCF:

                              https://github.com/Tircown/ERCF-easy-brd

                              Link to the project:

                              https://github.com/EtteGit/EnragedRabbitProject

                              oc_geekundefined 1 Reply Last reply Reply Quote 0
                              • oc_geekundefined
                                oc_geek @Dan1990
                                last edited by

                                @dan1990 rightly said

                                in particular the part responsible for the Pulse Generating encoder is a Klipper module written in python

                                1 Reply Last reply Reply Quote 0
                                • pfnundefined
                                  pfn @oc_geek
                                  last edited by pfn

                                  @oc_geek why would you need 250hz? 1 pulse per mm, feed rates are usually like 10mm/s at most... (browsing that code, it looks like it's set at 1.5mm/pulse and something like 100mm/s feed rate, it's probably reasonable enough?)

                                  oc_geekundefined 1 Reply Last reply Reply Quote 0
                                  • oc_geekundefined
                                    oc_geek @pfn
                                    last edited by oc_geek

                                    @pfn as i wrote this came from the Author of the unit itself... it's not that i need something..

                                    834f357d-1bea-404a-89f1-28ae18572708-image.png

                                    The sensor is used ONLY when loading / unloading the chosen (between nine) filament to the tool to make sure it arrives where intended and does not jam the unit and so on...
                                    I think they do that faster than a print feed rate to reduce the overall print time...(e.g. 1000 filament changes in a print would matter..)

                                    that said i did not got any data point from the Duet team on which rates (Hz) are reachable using a trigger... or any other offered solution...

                                    pfnundefined 1 Reply Last reply Reply Quote 0
                                    • pfnundefined
                                      pfn @oc_geek
                                      last edited by

                                      @oc_geek it may be too fast to push 250 triggers a second (even though it should be brief). 250 triggers a second would be something like 375mm/s feed rate, is the ercf really capable of that? In any case, if RRF isn't capable of that speed of triggering, you can solve it with several means.

                                      1. Decrease the pulse resolution, i.e. remix the encoder wheel so that pulses are every 3mm rather than 1.5, decrease resolution until it is manageable, if it is an issue.

                                      2. Even easier is to simply lower the feed rate , 100mm/s is already really fast, adjust until pulse counts are manageable.

                                      I'd prefer to do 1. Anyhow, if you already have a smart filament sensor handy, it wouldn't be very hard to test to see what kind of rate you can achieve, yank filament through and see how many triggers you can capture.

                                      As for the duet team not giving a number, I'm not sure anyone even tests this scenario...

                                      oc_geekundefined 1 Reply Last reply Reply Quote 0
                                      • oc_geekundefined
                                        oc_geek @pfn
                                        last edited by

                                        @pfn yeah will have to check as you say

                                        Option 1 is not possible as the "encoder wheel" is actually a metal Bondtech gear (as i wrote before below)

                                        Option 2 seems to be the only practical possibility

                                        Also the challenge will be to port the Klipper python module into RRF Marcos...

                                        pfnundefined 3 Replies Last reply Reply Quote 0
                                        • pfnundefined
                                          pfn @oc_geek
                                          last edited by

                                          @oc_geek ah, that's fascinating, so roughly 1.4mm per pulse, and it seems Ette runs about 170mm/s for the high speed part of the load -- the actual pulse rate that needs to be supported is about 125 per second (if you want to use what Ette runs), 75 pulses per second otherwise (100mm/s default).

                                          Anyway, yeah, test it out with a rotary encoder and see what sort of numbers can be achieved.

                                          1 Reply Last reply Reply Quote 0
                                          • pfnundefined
                                            pfn @oc_geek
                                            last edited by pfn

                                            @oc_geek so, I happened to be building a filament sensor anyway 😁 -- you're in luck and I'm able to give some general data (for duet2wifi)

                                            This sensor design generates 1 pulse for every 0.98mm of filament travel, calculated by 7.5mm filament gear diameter driving a 24 spoke encoder wheel. (pi*7.5/24)

                                            https://cdn.discordapp.com/attachments/711873626080804917/893167909621334076/unknown.png
                                            https://cdn.discordapp.com/attachments/711873626080804917/893288891535228948/20210930_171026.jpg

                                            I'm running this on a spare duet2wifi testbed board. The printer I intend to use with the ERCF is using a duet3 6mbhc, but isn't available for testing. Interestingly, my filament sensor will become obsolete as I will move the function of filament sensing to the ERCF's optical pickup; luckily I have another printer I can put the filament sensor on 😄

                                            I wrote the following macros:

                                            /macros/setup sensor

                                            M950 J1 C"e0stop"
                                            M581 P1 T2 R0 S1
                                            
                                            if !exists(global.pulse_count)
                                              set global pulse_count = 0
                                              
                                            if !exists(global.wall_time)
                                              global wall_time = 0
                                              
                                            if !exists(global.last_time)
                                              global last_time = 0
                                            
                                            set global.pulse_count = 0
                                            set global.wall_time = 0
                                            set global.last_time = 0
                                            

                                            /macros/echo data:

                                            echo {global.pulse_count ^ " " ^  global.last_time - global.wall_time}
                                            set global.pulse_count = 0
                                            set global.wall_time = 0
                                            set global.last_time = 0
                                            

                                            /sys/trigger2.g

                                            if global.pulse_count = 0
                                              set global.wall_time = {state.upTime + state.msUpTime / 1000}
                                            
                                            set global.last_time = {state.upTime + state.msUpTime / 1000}
                                            set global.pulse_count = {global.pulse_count + 1}
                                            

                                            With this setup, I was able to process about 70-100 pulses per second (just averaging). Most of the trials were about 80 pulses per second. Testing consisted of pulling a 500mm length of filament through the sensor at varying durations (from 1-10 seconds). At about 6 seconds, the full pulse count could be achieved. Anything under that aliased to between 70 and 100 pulses per second.

                                            Duet3 may perform more adequately. But if we were putting an ERCF on a duet2, I'd probably go with a 90mm/s loading feedrate.

                                            Aliasing of the pulses may be an artifact of the optical sensor (endstop) I'm using, I'm not sure what its max trigger rate could be. Lots of variables; the sensor in the ERCF could have better performance.

                                            pfnundefined 1 Reply Last reply Reply Quote 1
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