AMIS-30624 Datasheet, PDF (35/56 Pages) AMI SEMICONDUCTOR – I2C Microstepping Motordriver

AMIS-30624
Velocity
V_max
V_min
Vbemf
Vbemf
Motor speed
t
V_bemf
+ ΔTHR
V_bemf
- ΔTHR
t
V_ABSTH
Back emf
DeltaStallHi
t
t
AbsStall
DeltaStallLo
t
t
Figure 22: Triggering of the Stall Flags in Function of Measured Back emf and the Set Threshold Levels
Table 24: Truth Table
Condition
Vbemf < Average - DelThr
Vbemf > Average + DelThr
Vbemf < AbsThr
<DelStallLo>
1
0
0
<DelStallHi>
0
1
0
<AbsStall>
0
0
1
<Stall>
1
1
1
The motion will only be detected when the motor is running at the maximum velocity, not during acceleration or deceleration.
If during positioning a mechanical obstacle is detected (stall), an (internal) hardstop is generated. The motor will stop immediately and
as a consequence the <StepLoss> and <Stall> flags are set. The position in the internal counter will be copied to the ActPos register.
All flags can be read out with the GetFullStatus1.
If Stall appears during DualPosition then the first phase is cancelled (via internal Hardstop) and after timeout (26.6ms) the second
phase at V_min starts.
Important Remark:
Using GetFullStatus1 will read AND clear the following flags: <Steploss>, <Stall>, <AbsStall>, <DelStallLo>, and
<DelStallHi>. New positioning is possible and the ActPos register will be further updated.
Motion detection is disabled when the RAM registers AbsThr[3:0] and DelThr[3:0] are empty or zero. Both levels can be programmed
using the I²C command SetStallParam in the registers AbsThr[3:0] and DelThr[3:0]. Also in the OTP register AbsThr[3:0] and
DelThr[3:0] can be set using the I²C command SetOTPParam. These values are copied in the RAM registers during power on reset.
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