TMCM-102 StallGuard

[flaonline]

Hello

I'm using a TMCM-102 module to drive a Haydon Kerk stepper motor. The motor has a maximum coil current of 1.5 A, the TMCM-102 is designed for motors up to 3.5A coil current.

I just can find combinations of speed/current which returns a StallGuard value of 3-4 (in TMCL-IDE), so I set the StallGuard Threshold to 5 to find the mechanical stop. The problem is, that sometimes the StallGuard value 5 is read during reference search and the motor stops. If I set the Threshold to 6, the motor runs into the mechanical stop without stoping. Now I'd like to set up the TMCM-102 for motor currents up to 1.5A to get StallGuard values in a better range. I've read a lot in the manuals and datasheets. I'll change the value of RSH, RSA and RSB to 0.15 ohms. Would this work? Or is it not possible to get better StallGuard values by changing the sense resistors? Did I forget anything important? What would you suggest to get useful StallGuard values?

Thank you for your help.

Flavio

[TRINAMIC_BD]

Hello,
you are right, the TMCM-102 is adapted for a higher motor current, so stallGuard for low current motors delivers less signal. With a higher sense resistor value, you will get better response. The motor current limit will scale down with the increase in the sense resistor.

[flaonline]

I've tested it, but I didn't get better StallGuard values. So we're performing tests with a light barrier now.

Regardless, I've got one more question about StallGuard: Are there special motor requirements to use StallGuard? Perhaps low coil resistance ore anything like that? I've read in the internet, that there are restrictions on motor. If there is any possibility to use StallGuard in our application we would prefer that because of saving costs.

Thank you for your help.

[Olav Kahlbaum (TRINAMIC)]

Low coil resistance is good for stallGuard. It also depends highly on the motor velocity you are using. Please run the motor with the stallGuard Profiler (built into the TMCL-IDE) to see at which velocities you can get a good stallGuard signal from your motor.