iC-TW8 16-BIT SIN/COS INTERPOLATOR
Serial Configuration Mode
Jan 9, 2013 Page SC9/36
These conditions can be monitored in real time over
either of the serial ports by reading the STAT_EE
register in the VAR block in internal memory.
Auto Store
The iC-TW8’s Auto Store feature automatically
stores adapted parameter values to the EEPROM
during operation for use as the startup values at the
next power-up. A double buffer is used which en-
sures a consistent set of AB signal path parameters
at every startup. Auto store is controlled by varia-
bles in the ADPT_STORE register in the CFG block
of internal memory.
The conditions that activate or latch the FAULT
output are determined by bits in the FLT_CFG and
FLT_EN registers in the CFG block in internal
memory.
ADC and Adaption Quality Monitors
The iC-TW8 provides a sophisticated quality evalu-
ation feature with a hardware STATUS output (pin
19) to monitor signal amplitude and auto adaption
during operation. Operation of the quality monitors
is controlled by bits in the MON_CFG register in
the CFG block in internal memory. Real-time quali-
ty status is also available over the serial ports.
Fault Handling
The iC-TW8 provides comprehensive fault handling
features and a hardware FAULT output (pin 20) to
notify external systems of faults and warnings dur-
ing operation. Real-time fault status is also available
over the serial ports.
The following signal path conditions are monitored
and can be configured to activate the FAULT out-
put.
The ADC Quality Monitor continuously evaluates
the amplitude of the sensor signal at the output of
the analog-to-digital converters in the AB signal
path and provides a pulse-width modulated signal
on the STATUS output that is inversely proportional
to relative signal amplitude. Thus the STATUS out-
put can be used to drive an LED whose brightness
or color is proportional to sensor signal amplitude
for early warning of a possible future failure. The
ADC quality monitor levels are determined by vari-
ables in the MON_ADC register in the CFG block
in internal memory.
Signal Path Fault/Status
Conditions
ADC overflow
ADC underflow
Excessive adaption
Speed limit exceeded
Overspeed warning
Fatal overspeed fault
Excessive filter lag
Excessive AB output lag
1-wire interface time-out
External crystal fault
The Adaption Quality Monitor continuously evalu-
ates the deviation of the adapted AB signal path pa-
rameters from their base values and provides a
pulse-width modulated signal on the STATUS out-
put that is proportional to the amount of deviation.
Thus the STATUS output can be used to drive an
LED whose brightness or color is proportional to
the relative amount of adaption that has occurred for
early warning of a possible future failure. The adap-
tion quality monitor levels are determined by varia-
bles in the MON_OFF, MON_GAIN, and
MON_PHASE registers in the CFG block in inter-
nal memory.
These conditions can be monitored in real time over
either of the serial ports by reading the STAT_SP
register in the VAR block in internal memory.
The following EEPROM conditions are monitored
and can be configured to activate the FAULT out-
put.
EEPROM Fault/Status
Conditions
Communication timeout
Hardware fault
Wrong EEPROM ID
CFG block checksum error
PAR Block 0 checksum error
PAR Block 1 checksum error
PAR_BASE block checksum error
LUT block checksum error
Wrong configuration mode
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