AMIS-30623 Datasheet, PDF (21/65 Pages) AMI SEMICONDUCTOR – LIN Microstepping Motordriver

AMIS-30623
14.1.5. External Switch SWI
As illustrated in Figure 13 the SWI comparator is almost identical to HW2. The major difference is in the limited number of states. Only
open or closed is recognised leading to respectively ESW = 0 and ESW = 1.
IÎ R
S_{PASS_T}
SWI
S_TOP
S_BOT
DriveHS
DriveLS
LOGIC
State
Closed
Open
1
2
1 = R2GND
2 = R2VBAT
3 = OPEN
"R"-Comp
3
IÎ R
S_{PASS_B}
COMP
32 μs Debouncer
R_th
SWI_Cmp
Figure 13: Simplified Schematic Diagram of the SWI Comparator
As illustrated in Figure 15 a change in state is always synchronised with DriveHS or DriveLS. The same synchronisation is valid for
updating the internal position register. This means that after every current pulse (or closing of S_TOP or S_BOT) the state of position switch
together with the corresponding position is memorised.
Using the GetActualPos commands reads back the ActPos register and the status of ESW. In this way the master node may get
synchronous information about the state of the switch together with the position of the motor. See Figure 14 below:
Byte
0
1
2
3
4
Content
Identifier
Data 1
Data 2
Data 3
Data 4
Bit 7
*
ESW
VddReset
Reading Frame
Structure
Bit 6 Bit 5 Bit 4 Bit 3
*
1
0 ID3
AD[6:0]
ActPos[15:8]
ActPos[7:0]
StepLoss ElDef UV2 TSD
Bit 2
ID2
TW
Figure 14: GetActualPos LIN commando
Bit 1 Bit 0
ID1 ID0
Tinfo[1:0]
Important remark. Every 512μs this information is refreshed.
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