iC-TW8 16-BIT SIN/COS INTERPOLATOR
Serial Configuration Mode
Jan 9, 2013 Page SC30/36
For example, assume it is desired to have the Z out-
put pulse centered within the input cycle. In this
case, zpos should be set to a nominal value of
Using Serial-Only Output Mode
The iC-TW8 contains a 32-bit sensor position (an-
gle) counter that can be accessed through either of
the serial ports. Instantaneous sensor velocity can
also be accessed via the serial ports. While the serial
ports can be used to read position and velocity in all
output modes, serial-only output mode removes the
maximum AB output frequency limit, fab, allowing
higher sensor speeds. Enter Serial for the Output
Mode in the General Configuration tab of the design
tool and the A, B, and Z outputs are disabled.
zwi dth[]
zpos[]180
2
and the analog index sensor signal must be roughly
in-phase with the COS– input. As shown in Figure
30, the Z gating signal will meet the index width
requirement if its transitions fall anywhere in the
gray areas of the waveform.
Serial-only output mode is not explicitly handled in
the design tool, although the design tool may still be
used for iC-TW8 configuration. See the iC-TW8
Programmer’s Reference for information on the se-
rial ports, the 32-bit position variable POS, and the
sensor velocity variable VEL in the WM block in
internal memory.
1 Input Cycle
SIN
COS
0°
90° 180° 270° 360°
Analog
Index Sensor
Signal
zth
Z Gating
Signal
Internal
Z Pulse
zwidth
OUTZ
zpos
Figure 30: Analog Index Sensor Example
Any deviations from ideal synchronization of the
index signal to the COS– signal due to production
tolerances can then be compensated by adjusting the
nominal zpos value, if necessary.
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