TinyG and SR4+ Driver

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  • September 16, 2021 at 9:59 am #12083
    mberger
    Participant

    I am trying to control some stepper motors with a TinyG v9 using external Moons SR4+ drivers and I am experiencing an issue similar to the one explained in this forum linked:
    https://synthetos.comtopics/external-drivers-with-tinyg

    I am noticing that on the start of the command, the drivers seem to not be enabled quick enough too start the motor and I am hearing a sound which is similar to that when the motors are under powered. Eventually, the drivers click to enabled and the motor runs with no problems.

    2 methods fix the issue, but neither is a perfect solution.
    1. Turn the jerk value down significantly, which has the obvious tradeoff of slower acceleration.
    2. Change the power management mode to always enable, which has the tradeoff of wasted power and added heat to my machine.

    Does anyone have any other suggestions?

    September 16, 2021 at 7:16 pm #12084
    cmcgrath5035
    Moderator

    tinyGV9 is 3.3v logic. Are you using level translators between V9 and the SR4+? if not, you might be seeing a slow turn on of the enable (bar) signal due to low current drive.

    Choosing power management to always on will not be much different than power management= in-cycle, as long as you remember to turn off the motors when you machine is idle. If $pm=1 works better, , then level translators might be in your future
    See https://github.com/synthetos/g2/wiki/G2core-on-DUE—External-Interfaces

    September 17, 2021 at 9:57 am #12085
    mberger
    Participant

    Thanks for the info!

    Yes, it definitely seems like the issue is a slow turn of the enable signal. I was under the impression that changing the jumper on the V9 from 3.3V to 5V meant that it would output 5V logic. Is that a wrong assumption?

    September 17, 2021 at 3:28 pm #12086
    cmcgrath5035
    Moderator

    I think it is not a good assumption.
    From looking at the schematic, that jumper only affects the Spindle out put levels.
    The VDD to the core processor is 3.3v and the connections to the 8825 drivers are direct. You could probe the enable[bar] with a volt meter to verify.
    Did you try power management always on to see if that improved the delay observed. Of course if enable is being delayed, it is possible the other signals will suffer similar distortion.

    The V9 was an early prototype development board, it did find it’s way into a few start up projects. Never fully documented.

    September 17, 2021 at 5:08 pm #12087
    mberger
    Participant

    Yes, it seems that power management always on definitely fixes the issue. We were worried about the internal temp of our machine, but it seems to be negligible enough that we are going to proceed with using this setting.

    Thanks for the help!

    September 18, 2021 at 7:59 am #12088
    cmcgrath5035
    Moderator

    Keep an eye on things. I have no idea what sort of machine or jobs you are running. IF(still not conclusive) marginal drive into your SR4+ was the culprit, you are essentially running a digital system in a fuzzy space between full digital precision and analog. Minor power variations, room temperature, etc could effect operation and or accuracy. Use the least amount of microstepping in your system to get the precision you need. Microstepping is an inherently analog process, playing with phase relationships in the windings.

    That said, good luck with your projects

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