Hello Rick,
thanks for your reply.
Unfortunately, I just recognized a bug in the code for evaluation of the register content. I suppose, that the right value that suddently appears is 7F (Mask corrected from 4F -> 7F) - seems that the drv8308 is not responsive.
I have seen this value (unmasked = 65535), when device isn't powered. In the faulty case, the other driver still have power above minimum threshold (in my project, there are three motors each driven by drv8308, which are all connected to the same voltage source).
I monitor the motor current but not per phase. The summarized current is < 300 mA.
I have logged some information, perhaps it's helpful for you:
motor=1 Speed1= 0 Speed2= -97 I= 170 pwm= -51 st=0 pos=27110
motor=1 Speed1= -200 Speed2= -148 I= 306 pwm= -41 st=0 pos=27108
motor=1 Speed1= -100 Speed2= -146 I= 168 pwm= -41 st=0 pos=27107
motor=1 Speed1= -100 Speed2= -142 I= 199 pwm= -42 st=0 pos=27106
motor=1 Speed1= -100 Speed2= -139 I= 226 pwm= -32 st=0 pos=27105
motor=1 Speed1= -100 Speed2= -133 I= 141 pwm= -32 st=0 pos=27104
motor=1 Speed1= 0 Speed2= -88 I= 94 pwm= -39 st=0 pos=27104
motor=1 Speed1= -200 Speed2= -129 I= 92 pwm= -30 st=0 pos=27102
motor=1 Speed1= -100 Speed2= -127 I= 112 pwm= -29 st=0 pos=27101
motor=1 Speed1= 0 Speed2= -68 I= 121 pwm= -41 st=0 pos=27101
motor=1 Speed1= -100 Speed2= -118 I= 209 pwm= -26 st=0 pos=27100
motor=1 Speed1= -100 Speed2= -118 I= 38 pwm= -24 st=0 pos=27099
motor=1 Speed1= -100 Speed2= -108 I= 59 pwm= -40 st=0 pos=27098
motor=1 Speed1= -100 Speed2= -111 I= 165 pwm= -40 st=0 pos=27097
motor=1 Speed1= -100 Speed2= -109 I= 197 pwm= -55 st=0 pos=27096
################### drv8308-fault: 4f ###################
motor=1 Speed1= 0 Speed2= -97 I= 0 pwm= -55 st=79 pos=27096
motor=1 Speed1= 0 Speed2= 0 I= 0 pwm= -55 st=79 pos=27096
motor=1 Speed1= 100 Speed2= 0 I= 0 pwm= -55 st=79 pos=27097
motor=1 Speed1= 0 Speed2= 0 I= 0 pwm= -55 st=79 pos=27097
motor=1 Speed1= 0 Speed2= 0 I= 0 pwm= -55 st=79 pos=27097
motor=1 Speed1= 0 Speed2= 0 I= 0 pwm= -55 st=79 pos=27097
motor=1 Speed1= 0 Speed2= 0 I= 0 pwm= -55 st=79 pos=27097
motor=1 Speed1= 0 Speed2= 0 I= 0 pwm= -55 st=79 pos=27097
motor=1 Speed1= 0 Speed2= 0 I= 0 pwm= -55 st=79 pos=27097
motor=1 Speed1= 0 Speed2= 0 I= 0 pwm= -55 st=79 pos=27097
Speed1 is calculated from hall-signals
Speed2 is calculated from time between slopes on TACH-signal (FGOUT)
I is the measured current [mA]
st is the value of register 2A masked by the faulty value 4F
Pos is position calculated from hall-signals
Update cycle is 10 ms
The current seems to be Ok.
Do you have any idea ?
Best regards
Marco