Two issues with stepper motors

[Skullbot]

I’ve finally managed to put everything together and get the firmware uploaded to the Huzzah32. After powering it on and going to cnc.html I noticed two problems with my stepper motors.

Firstly, when I click Home All the motor connected to the top arm doesn’t move at all. The lower arm homes properly and stops at the bottom optical sensor. The top arm then sits still while the number of steps and the X/Y positions on cnc.html continue to update. Likewise, pressing X-100, X+100, Y-100, Y+100 all have only the lower arm rotate. I’m not exactly sure why this is happening. The only parts that differ from the sand table post are the optical sensors, but those shouldn’t be affecting the upper stepper motor’s ability to rotate the arm. I also made sure that I copy pasted the RobotConfig from the post and that the axis1 stepPin is 27 on the cnc.html settings section.

The second issue occurs after the table ‘homes’ aka the lower arm is in the correct position. While it is idling I noticed that the lower arm was slowly moving. Every couple of seconds (not consistently) I would hear a quiet clicking sound due to the lower arm rotating a very slight amount. My guess is that the stepper motor is rotating it the minimum amount it can for some reason? Anyway, this is less of an obvious issue than the previous one, but it still needs to be resolved since the lower arm can get centimeters out of position in just a few minutes.

Any help towards figuring out what is happening with this would be greatly appreciated!

[bliksem]

I’m basically at the same point, home only moves the lower arm. If I swap around the stepper motor cables on the board at STEP1 and STEP2 then the top arm rotates, but not the lower. I swapped around the stepper drivers and the top or lower arm rotates depending on which one is connected to STEP1.
So stepper drivers are good, stepper motor cables are good.
I resoldered all the joints on the board in case I missed something, or had a dry joint.

Just as a side note, the stepper driver heat sinks burnt my finger when I accidentally touched them, they were super hot. Vref was set at 1.2V and I dropped it to 0.8V, they are running much cooler now.

[Matt G]

You’ve gone through the initial troubleshooting I would have. Can you probe the driver pins and see if they are getting the correct signals?

[bliksem]

I only have a multimeter, I checked accross the inner and outer pairs of the STEP1 and STEP2 pins.
On STEP1 (which is working) I get fluctuating voltages as expected, on STEP2 I get a constant 1.5V

[bliksem]

I had the wrong config loaded… after rereading everything for the umpteenth time I realized that I need to load the modified config posted below

[bliksem]

{
“robotType”: “SandTableScaraMatt”,
“cmdsAtStart”: “”,
“webui”: “SandUI”,
“evaluators”: {
“thrContinue”: 0
},
“robotGeom”: {
“model”: “SingleArmScara”,
“homing”: {
“homingSeq”: “FR10;A+10000N;B-10000;#;A+5000n;B-5000;#;B+10000N;#;B+5000n;#;A=h;B=h;$”,
“maxHomingSecs”: 120
},
“blockDistanceMM”: 1,
“allowOutOfBounds”: 0,
“stepEnablePin”: “12”,
“stepEnLev”: 0,
“stepDisableSecs”: 10,
“axis0”: {
“maxSpeed”: 9,
“maxAcc”: 50,
“maxRPM”: 2,
“stepsPerRot”: 9600,
“unitsPerRot”: 628.318,
“maxVal”: 185,
“stepPin”: “14”,
“dirnPin”: “32”,
“endStop0”: {
“sensePin”: “36”,
“actLvl”: 0,
“inputType”: “INPUT_PULLUP”
}
},
“axis1”: {
“maxSpeed”: 9,
“maxAcc”: 50,
“stepsPerRot”: 9600,
“unitsPerRot”: 628.318,
“maxRPM”: 2,
“maxVal”: 185,
“stepPin”: “27”,
“dirnPin”: “15”,
“endStop0”: {
“sensePin”: “39”,
“actLvl”: 0,
“inputType”: “INPUT_PULLUP”
}
}
},
“fileManager”: {
“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”
}
}

[Skullbot]

Alright, I’ve got a myriad of problems and am no closer to solving them after a week of troubleshooting.

So, first off: Couldn’t figure out why the upper arm wasn’t rotating. Soldered together an entirely new board, plugged it in, upper arm rotates now. Guess the issue was with one of my solder joints.

Also added the code from the ‘Stepper Motor Disable’ thread, hopefully that has fixed the slowly rotating lower arm but I’m not sure because of…all the other issues that have cropped up. Namely:

1. When I provide power to the PCB the huzzah32 light turns on. cnc.html loads up, the machine is in the running state. When I hit home all…nothing happens. Likewise, entering new commands into the settings page and hitting save does nothing. Refreshing the page creates a popup saying ‘failed to send new settings’. This only happens sometimes, other times the robot works fine.

2. When the machine isn’t working, the files tab on cnc.html no longer shows how many MB of space there are to use.

3. When the robot is working, I press home all. The lower arm rotates until it’s in line with the machine. The upper arm rotates and stops slightly out of line. This is due to me having to finagle the optical sensor to stop the arm from hitting it as it rotates. I modified the homing string so that after the upper arm hits the optical sensor, it rotates back a few steps to get back in line. The problem is, when this happens, the lower arm rotates a little bit clockwise out of position at the same time. Here is the modified homing string:
"FR10;A+10000N;B-10000;#;A+5000n;B-5000;#;B+10000N;#;B+5000n;#;B-180;#;A=h;B=h;$"

4. When the machine is working, sometimes it stops accepting commands. As in, I’ll be modifying the homing string or messing with X/Y positions to try and determine why rotating the upper arm also rotates the lower arm and suddenly hitting home all or X+100 or Y-10 does nothing. At which point I need to unplug/hit the reset button on the huzzah32 after which there are decent odds of the robot suddenly not working.

This is extremely annoying and difficult to troubleshoot, doubly so when the issue you want to troubleshoot becomes impossible to work on at what seem like arbitrary times. Any advice on how to proceed?

[Jason]

hi Skullbot，
I also encountered the same problem as you. the lower arm was slowly moving.how did you solve it？
Best wishes!

[geri]

#jason # skullbot Hello I think the problem is pin 14 that is the bin to step I cut it on the board and connected it to pin 13 and in the cncui you have to change in then it works, hope you have success lg

[beastie417]

#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″}}

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