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| author | Kevin O'Connor <kevin@koconnor.net> | 2020-03-29 11:06:06 -0400 |
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| committer | Kevin O'Connor <kevin@koconnor.net> | 2020-03-29 11:08:49 -0400 |
| commit | 3c01b60a8846748d918e131d9307f7bce5a3e217 (patch) | |
| tree | 8c9518ea601abad2062f3c20651668aeee1ef31c /docs/FAQ.md | |
| parent | 77177582cdfd9313481c3c3538c53b98c7dc4088 (diff) | |
| download | kutter-3c01b60a8846748d918e131d9307f7bce5a3e217.tar.gz kutter-3c01b60a8846748d918e131d9307f7bce5a3e217.tar.xz kutter-3c01b60a8846748d918e131d9307f7bce5a3e217.zip | |
docs: Update FAQ with TMC2208 "standalone" mode workaround
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Diffstat (limited to 'docs/FAQ.md')
| -rw-r--r-- | docs/FAQ.md | 45 |
1 files changed, 5 insertions, 40 deletions
diff --git a/docs/FAQ.md b/docs/FAQ.md index 1cf89f08..2c7af7c7 100644 --- a/docs/FAQ.md +++ b/docs/FAQ.md @@ -256,46 +256,11 @@ configured in Marlin. ### My TMC motor driver turns off in the middle of a print -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! - -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. +If using the TMC2208 (or TMC2224) driver in "standalone mode" then +make sure to use the +[latest version of Klipper](#how-do-i-upgrade-to-the-latest-software). A +workaround for a TMC2208 "stealthchop" driver problem was added to +Klipper in mid-March of 2020. ### I keep getting random "Lost communication with MCU" errors |