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diff --git a/docs/FAQ.md b/docs/FAQ.md index 0f1eea53..bde845b2 100644 --- a/docs/FAQ.md +++ b/docs/FAQ.md @@ -265,17 +265,46 @@ configured in Marlin. ### My TMC motor driver turns off in the middle of a print -There have been reports of some TMC drivers being disabled in the -middle of a print. (In particular, with the TMC2208 driver.) When this -issue occurs, the stepper associated with the driver moves freely, -while the print continues. +Short answer: Do not use the TMC2208 driver in "standalone mode" with +Klipper! Do not use the TMC2224 driver in "stealthchop standalone +mode" with Klipper! -It is believed this may be due to "over current" detection within the -TMC driver. Trinamic has indicated that this could occur if the driver -is in "stealthChop mode" and an abrupt velocity change occurs. If you -experience this problem during homing, consider using a slower homing -speed. If you experience this problem in the middle of a print, -consider using a lower square_corner_velocity setting. +Long answer: Klipper implements very precise timing. + + + +In the above picture, if Klipper is requested to move along the red +line and if each black line represents the nominal location to step a +stepper, then in the middle of that movement Klipper will arrange to +take a step, change the step direction, and then step back. Klipper +can perform this step, direction change, and step back in a very small +amount of time. + +It is our current understanding that the TMC2208 and TMC2224 will +react poorly to this when they are in "stealthchop" mode. (It is not +believed any other TMC drivers are impacted.) It is believed that when +the driver sees the two step requests in a small time frame that it +dramatically increases current in anticipation of high acceleration. +That high current can trip the driver's internal "over current" +detection which causes the driver to disable itself. + +This pattern of steps can occur on all stepper motors and on all +robot kinematics. + +The TMC2208 and TMC2224 do work well with Klipper when run-time +configuration mode is used (that is, when a wire is routed from the +micro-controller to the PDN-UART pin and the printer config file has a +corresponding [tmc2208] config section). When using run-time +configuration, either configure the drivers to use "spreadcycle mode" +or configure them to use "stealthchop mode" with a reasonable +"stealthchop threshold". If one wishes to exclusively use +"stealthchop" mode with run-time UART configuration then make sure the +stealthchop_threshold is no more than about 10% greater than the +maximum velocity of the given axis. It is speculated that with a +reasonable stealthchop threshold, then if Klipper sends a "step, +direction change, step back" sequence, the driver will briefly +transition from stealthchop mode, to spreadcycle mode, and back to +stealthchop mode, which should be harmless. ### I keep getting random "Lost communication with MCU" errors diff --git a/docs/img/tmc2208.svg b/docs/img/tmc2208.svg new file mode 100644 index 00000000..0a2d8c6e --- /dev/null +++ b/docs/img/tmc2208.svg @@ -0,0 +1,96 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!-- Created with Inkscape (http://www.inkscape.org/) --> + +<svg + xmlns:osb="http://www.openswatchbook.org/uri/2009/osb" + xmlns:dc="http://purl.org/dc/elements/1.1/" + xmlns:cc="http://creativecommons.org/ns#" + xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" + xmlns:svg="http://www.w3.org/2000/svg" + xmlns="http://www.w3.org/2000/svg" + xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd" + xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape" + width="210mm" + height="297mm" + viewBox="0 0 210 297" + version="1.1" + id="svg8" + inkscape:export-filename="/home/kevin/bitmap.png" + inkscape:export-xdpi="96" + inkscape:export-ydpi="96" + inkscape:version="0.92.3 (2405546, 2018-03-11)" + sodipodi:docname="move-desc.svg"> + <defs + id="defs2"> + <linearGradient + id="linearGradient4609" + osb:paint="solid"> + <stop + style="stop-color:#ffffff;stop-opacity:1;" + offset="0" + id="stop4607" /> + </linearGradient> + </defs> + <sodipodi:namedview + id="base" + pagecolor="#ffffff" + bordercolor="#666666" + borderopacity="1.0" + inkscape:pageopacity="1" + inkscape:pageshadow="2" + inkscape:zoom="0.98994949" + inkscape:cx="429.37872" + inkscape:cy="710.19584" + inkscape:document-units="mm" + inkscape:current-layer="layer1" + showgrid="false" + inkscape:pagecheckerboard="false" + inkscape:window-width="1182" + inkscape:window-height="699" + inkscape:window-x="237" + inkscape:window-y="79" + inkscape:window-maximized="0" /> + <metadata + id="metadata5"> + <rdf:RDF> + <cc:Work + rdf:about=""> + <dc:format>image/svg+xml</dc:format> + <dc:type + rdf:resource="http://purl.org/dc/dcmitype/StillImage" /> + <dc:title></dc:title> + </cc:Work> + </rdf:RDF> + </metadata> + <g + inkscape:label="Layer 1" + inkscape:groupmode="layer" + id="layer1"> + <path + style="fill:none;fill-rule:evenodd;stroke:#000000;stroke-width:0.26458332px;stroke-linecap:butt;stroke-linejoin:miter;stroke-opacity:1" + d="M 40.398947,86.676759 169.6668,87.432709" + id="path4518-3" + inkscape:connector-curvature="0" /> + <path + style="fill:none;fill-rule:evenodd;stroke:#000000;stroke-width:0.26458332px;stroke-linecap:butt;stroke-linejoin:miter;stroke-opacity:1" + d="M 40.764446,101.81154 170.0323,102.56749" + id="path4518-6" + inkscape:connector-curvature="0" /> + <path + style="fill:none;fill-rule:evenodd;stroke:#000000;stroke-width:0.26458332px;stroke-linecap:butt;stroke-linejoin:miter;stroke-opacity:1" + d="m 40.702855,116.60959 129.267855,0.75595" + id="path4518-7" + inkscape:connector-curvature="0" /> + <path + style="fill:none;fill-rule:evenodd;stroke:#000000;stroke-width:0.26458332px;stroke-linecap:butt;stroke-linejoin:miter;stroke-opacity:1" + d="m 40.465706,131.82822 129.267854,0.75595" + id="path4518-5" + inkscape:connector-curvature="0" /> + <path + style="fill:none;fill-rule:evenodd;stroke:#fc0000;stroke-width:0.29816988px;stroke-linecap:butt;stroke-linejoin:miter;stroke-opacity:1" + d="M 66.015573,81.729992 C 95.790705,139.21551 118.11752,118.84351 138.71287,80.372264" + id="path4613" + inkscape:connector-curvature="0" + sodipodi:nodetypes="cc" /> + </g> +</svg> diff --git a/docs/img/tmc2208.svg.png b/docs/img/tmc2208.svg.png Binary files differnew file mode 100644 index 00000000..f46a6f8d --- /dev/null +++ b/docs/img/tmc2208.svg.png |
