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I’d be interested but someone needs to take the first step to setup a repo.
Hi Bram,
Looks like you are missing part of the main arm command. As an example, here is my homing sequence code:
{"homingSeq":"FR10;A+10000n;B-10000;#;A+5000N;B-5000;#;A+15;B-15;#;B+10000n;#;B+5000N;#;B+60;#;A=h;B=h;$","maxHomingSecs":120}One thing to note, the optical limit sensors I have are inverted polarity compared to Matt’s example. Good idea to check which polarity yours are. Also, the ‘#’ groups the commands. + and – determine motor direction.
Let’s dissect my homing sequence.
Part 1
FR10 - feed rate 10 is an OK speed on my table
Part 2
A+10000n;B-10000; - Turn Motor A Clockwise, Turn Motor B Counterclockwise until Limit Switch 1 goes low or 10000 steps
Part 3
A+5000N;B-5000; - Turn Motor A Clockwise, Turn Motor B Counterclockwise until Limit Switch 1 goes high or 5000 steps
Part 4
A+15;B-15; - Turn Motor A Clockwise, Turn Motor B Counterclockwise for 15 steps to better align the arms
Part 5
B+10000n; - Turn Motor B Clockwise until Limit Switch 2 goes low or 10000 steps
Part 6
B+5000N; - Turn Motor B Clockwise until Limit Switch 2 goes high or 5000 steps
Part 7
B+60; - Turn Motor B Clockwise for 60 steps to better align the upper arm
Part 8
A=h;B=h;$ - Make current arm positions 0,0As far as I know, this is the breakdown of the homing sequence commands. Hope this helps!
Are you still having this issue? My guess is the belt just isn’t tensioned enough. I use a premade 158mm belt and it is working well for my setup.
The issue appears to be that the “wifiLed” pin is the same as the step pin (14). I changed the step to pin 13 and presto! Alternatively I assume you can change “wifiLed” to something other than 14 if you don’t want to change the step pin.
From the RobotConfig posted on the main site:
{“spiffsEnabled”:1,”spiffsFormatIfCorrupt”:1,”sdEnabled”:1,”sdMOSI”:”18″,”sdMISO”:”19″,”sdCLK”:”5″,”sdCS”:”21″},”wifiLed”: {“hwPin”:”14″,”onLevel”:1,”onMs”:200,”shortOffMs”:200,”longOffMs”:750},”ledStrip”:{“ledPin”:”4″,”sensorPin”:”34″}}Thanks scott_12345! I added a pull-down resistor (2kOhm ish) to the stepper enable line and that fixed it for me!
#scott_12345 Not sure if you are still pursuing this but I am using the TMC2209 (very similar to TMC2208) stepper motor drivers on my table and ran into a similar issue. I don’t yet know why the issue is happening but I am able to work around it with some extra hardware. I am not familiar with the A4988 so can’t comment.
I am still in the early stages of finishing my table so I haven’t ordered a PCB yet but have all my circuitry working on a breadboard. Since I’m working on a breadboard adding this extra workaround circuitry wasn’t too bad. I suspect it would be difficult to add this onto an existing PCB unless you have superb soldering skills. See the circuitry I added below:
I did it this way because I happen to have these parts on hand. A much cleaner way would be to use something like the TPS22810 load switch. Of course the even cleaner way would be to figure out why this happens and fix it in software 🙂 I’ll update if I ever figure out what’s causing it.
#geri thank you for this comment! I was just in the process of trying to troubleshoot my slowly moving arm when I came across this post. This was absolutely my issue. I changed the step to pin 13 and presto! Alternatively I assume you can change “wifiLed” to something other than 14 if you don’t want to change the step pin.
From the RobotConfig posted on the main site:
{“spiffsEnabled”:1,”spiffsFormatIfCorrupt”:1,”sdEnabled”:1,”sdMOSI”:”18″,”sdMISO”:”19″,”sdCLK”:”5″,”sdCS”:”21″},”wifiLed”:{“hwPin”:”14″,”onLevel”:1,”onMs”:200,”shortOffMs”:200,”longOffMs”:750},”ledStrip”:{“ledPin”:”4″,”sensorPin”:”34″}}
