Operation Manual

8
Detailed Control Register Denitions
NOTE: Unless otherwise noted, all registers contain one byte and are read
and write.
0x00
R/W Name Description Initial Value
W ACQ_COMMAND Device command --
Bit Function
7:0 Write 0x00: Reset FPGA, all registers return to default values
Write 0x03: Take distance measurement without receiver bias correction
Write 0x04: Take distance measurement with receiver bias correction
0x01
R/W Name Description Initial Value
R STATUS System status --
Bit Function
6 Process Error Flag
0: No error detected
1: System error detected during measurement
5 Health Flag
0: Error detected
1: Reference and receiver bias are operational
4 Secondary Return Flag
0: No secondary return detected
1: Secondary return detected in correlation record
3 Invalid Signal Flag
0: Peak detected
1: Peak not detected in correlation record, measurement is invalid
2 Signal Overow Flag
0: Signal data has not overowed
1: Signal data in correlation record has reached the maximum value before
overow. This occurs with a strong received signal strength
1 Reference Overow Flag
0: Reference data has not overowed
1: Reference data in correlation record has reached the maximum value
before overow. This occurs periodically
0 Busy Flag
0: Device is ready for new command
1: Device is busy taking a measurement
0x02
R/W Name Description Initial Value
R/W SIG_COUNT_VAL Maximum acquisition count 0x80
Bit Function
7:0 Maximum number of acquisitions during measurement
0x04
R/W Name Description Initial Value
R/W ACQ_CONFIG_REG Acquisition mode control 0x08
Bit Function
6 0: Enable reference process during measurement
1: Disable reference process during measurement
5 0: Use default delay for burst and free running mode
1: Use delay from MEASURE_DELAY (0x45) for burst and free running mode
4 0: Enable reference lter, averages 8 reference measurements for increased
consistency
1: Disable reference lter
3 0: Enable measurement quick termination. Device will terminate distance
measurement early if it anticipates that the signal peak in the correlation
record will reach maximum value.
1: Disable measurement quick termination.
2 0: Use default reference acquisition count of 5.
1: Use reference acquisition count from REF_COUNT_VAL (0x12).
1:0 Mode Select Pin Function Control
00: Default PWM mode. Pull pin low to trigger measurement, device will
respond with an active high output with a duration of 10us/cm.
01: Status output mode. Device will drive pin active high while busy. Can be
used to interrupt host device.
10: Fixed delay PWM mode. Pulling pin low will not trigger a measurement.
11: Oscillator output mode. Nominal 31.25 kHz output. The accuracy of the
silicon oscillator in the device is generally within 1% of nominal. This affects
distance measurements proportionally and can be measured to apply a
compensation factor.
0x09
R/W Name Description Initial Value
R VELOCITY Velocity measurement output --
Bit Function
7:0 Velocity measurement output. The difference between the current
measurement and the previous one, signed (2’s complement) value in
centimeters.
0x0c
R/W Name Description Initial Value
R PEAK_CORR Peak value in correlation record --
Bit Function
7:0 The value of the highest peak in the correlation record.
0x0d
R/W Name Description Initial Value
R NOISE_PEAK Correlation record noise oor --
Bit Function
7:0 A measure of the noise in the correlation record. Will be slightly above the
third highest peak.