Hi Experts,
DRV8889-Q1 is under evaluation on customer side. When customer test the stall detection function, they have following questions, could you help on this? Thanks.
1. When DRV8889-Q1 in the intelligent tuning ripple control mode or other modes. regardless of whether the stall detection algorithm is enables or not, the value of CTR7.TRQ_CONT is updated in real time.
In the datasheet, in the intelligent tuning ripple control mode, the stall detection algorithm can be enabled. The stall judgment logic of the algorithm is like this: CTRL7.TRQ_COUNT <CTRL6.STALL_TH.
So: Can customer directly use software to replace the stall detection algorithm(when customer disable the stall detection, even the control mode in the non-recommended smart tuning ripple control mode)?
Customer just use the value of CTRL7.TRQ_COUNT and CTRL6.TRQ_COUNT to judge the stall fault.
2. What's the timing to turn on the stall detection? Cn it be turned on when customer send out the first STP pulse, or do they have to wait for a while for the motor speed to stabilize before turning on?
3. When customer use stall self-learning algorithm, it always unsuccessful. Customer suspect it's related to the motor speed, motor current(TRQ_DAV value)..etc.
What are the conditions for the implementation of stall self-learning, what factors will cause the failure of stall-learning, and how to evaluate whether a motor can use self-learning? Could you comment on this?
4. When customer tested and found that TRQ_COUNT value of a motor has dropped significantly under normal rotation and stalled/out-of-step conditions, which can be used for stall judgment. Customer tested this based on several motors. TRQ_COUNT value of another normal motor did not decrease significantly, even if the torque current is set to be less than the rated current of the motor(Such as: the rated current of the motor is 0.35A, I_FS=(3.3V/2)/2.2*TRQ_DAC=0.75*TRQ_DAC, set TRQ_DAC less than 50%).
May I ask what factors will prevent the stall detection algorithm form being used? Is it true that not all motors that meet the voltage and current requirements can use the stall algorithm to correctly diagnose the stall?
How to judge the need to use the actual motor to test multiple times in the working mode to determine whether the stall detection is applicable?( current TRQ_DAC, STEPPING MODE microstep_mode, under rated load, under specific speed)
Best Regards
Songzhen Guo
