Coil current sensing

Question

Hello,

I would want to monitor the current going through the stepper motor coils driven by a TMC5130A.
My goal is to be able to do predictive maintenance, and monitor if the load torque has suddenly increased.

(1) As I understand, the register MSCURACT can't really be used for that purpose since it only reflects the current value from the Look Up Table. Is my assumption correct ?

(2) I was thinking of using a High Side shunt 10mOhm resistor and a current-sense amplifier, hooked up to the ADC of a microcontroller.
However, I can't tell in the datasheet if the 2 VS pins are tied together in the ICs, or if each pin powers a single coil, and so if it would be relevant to have 2 shunt to measure the coils current.
Are the 2 VS pins tied together in the IC ?

BernhardDwersteg · Accepted Answer

Hi, yes, they are tied together in the IC, but due to interconnection resistance, this is much more than the 10mohm resistor. So, you could still use the resistor per connection. But, as the driver IC does a constant current driving, the motor current will match the target current as long as everything is fine. To check for coil resistance, you could work with StealthChop, and check for duty cycle register in standstill at each a halfstep position with coil A on and with coil B on, e.g. MSTEP 0 and 256. The duty cycle will tell you the actual coil resistance when multiplied by supply voltage and divided by target current.)

Partner Forums

Partner Libraries

Coil current sensing