AMIS-30623 LIN Microstepping Motordriver
Data Sheet
15.1.5. 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.
SPASS_T
IꢁR
State
DriveHS
Closed
SWI
STOP
LOGIC
SBOT
Open
DriveLS
"R"-Comp
1
2
3
IꢁR
SPASS_B
Rth
COMP
32 µs Debouncer
1 = R2GND
2 = R2VBAT
3 = OPEN
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 STOP or SBOT) 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:
Reading Frame
Byte
Content
Structure
Bit 7
*
ESW
Bit 6
*
Bit 5
1
Bit 4 Bit 3 Bit 2
Bit 1
ID1
Bit 0
ID0
0
ID3
ID2
0
1
2
3
4
Identifier
Data 1
Data 2
Data 3
Data 4
AD[6:0]
ActPos[15:8]
ActPos[7:0]
ElDef
VddReset
StepLoss
UV2
TSD
TW
Tinfo[1:0]
Figure 14: GetActualPos LIN commando
Important remark. Every 512µs this information is refreshed.
AMI Semiconductor – June 2006, Rev 3.0
22
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