IC-TW14 Datasheet, PDF (17/33 Pages) IC-Haus GmbH – IC-PMX Companion Chip

iC-TW14
iC-PMX Companion Chip
Rev A1, Page 17/33
SSI_OFS
SSI_OFS is a read/write register containing the angular
difference (offset) between the iC-PMX 0° point and the
point where the multiturn data provided over the SSI
multiturn interface is expected to roll over.
SSI_LENGTH
SSI_LENGTH is a read/write register used to specify
the length (number of bits) of the SSI data sent to the
external singleturn absolute sensor using the SSI multi-
turn interface.
Value
0 – 359
360 – 65,535
SSI_OFS (0x16)
Description
Singleturn sensor offset in degrees
Reserved (do not use)
Value
0 – 31
32 – 65,535
SSI_LENGTH (0x18)
Description
Number of bits of SSI data
Reserved (do not use)
Table 20: SSI_OFS Register
Table 22: SSI Data Length
SSI_OFS is used to calculate the multiturn position sent
to the external singleturn sensor via the iC-TW14’s SSI
multiturn interface. In applications where the external
singleturn absolute sensor uses the same magnet as
the iC-PMX, SSI_OFS can be set based on the geome-
try of the application. In applications where the external
singleturn absolute sensor is mechanically independent
of the iC-PMX/iC-TW14 turns counter, use the iC-TW14
NPRE input to set SSI_OFS as explained in PRESET
PIN (NPRE) on page 24.
SSI_DIR
SSI_DIR is a read/write register used to match the ro-
tation direction of the multiturn data provided over the
SSI multiturn interface to the rotation direction of the
external singleturn absolute sensor.
Value
0
1
2 – 65,535
SSI_DIR (0x17)
Description
Positive rotation is counterclockwise
Positive rotation is clockwise
Reserved (do not use)
Table 21: External Singleturn Sensor Rotation Direction
SSI_LENGTH must be set to match the connected sin-
gleturn absolute sensor. In general,
SSI_LENGTH = Multiturn Bits + Synchronization Bits
For example, if 16 bits of multiturn count and 1 sync bit
are required, set SSI_LENGTH = 17. See SSI MULTI-
TURN INTERFACE on page 25 for more information.
SSI_MSB
SSI_MSB is a read/write register used to specify the
starting (most significant) bit of the SSI data sent to the
external singleturn absolute sensor for initialization.
Value
0 – 31
32 – 65,535
SSI_MSB (0x19)
Description
Starting bit of SSI data
Reserved (do not use)
Table 23: SSI Data MSB
SSI_MSB must be set to match the connected single-
turn absolute sensor. In general,
SSI_MSB = Multiturn Bits − 1
If SSI_DIR = 0, counterclockwise rotation of the mag-
net as viewed when looking at the top of the iC-PMX
is positive (increasing SSI_MT and SSI_ST values).
If SSI_DIR = 1, clockwise rotation of the magnet as
viewed when looking at the top of the iC-PMX is posi-
tive. Set SSI_DIR to match the rotation direction of the
external singleturn absolute system for proper initializa-
tion and synchronization.
For example, if 16 bits of multiturn count and 1 sync bit
are required, set SSI_MSB = 15. See SSI MULTITURN
INTERFACE on page 25 for more information.