User manual

DocID026171 Rev 6 19/79
VL6180X Functional description
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2.5 Range timing
Figure 12 gives a breakdown of total execution time for a single range measurement.
• The pre-calibration phase is fixed (3.2 ms).
• The range convergence time is variable and depends on target distance/reflectance
(see Table 7).
• The recommended readout averaging period is 4.3 ms. Readout averaging helps to
reduce measurement noise. The recommended setting for
READOUT__AVERAGING_SAMPLE_PERIOD{0x10A} is 48
(c)
but is programmable in
the range 0-255. Note however that lower settings will result in increased noise.
Note: When a target is detected, register RESULT__RANGE_RETURN_CONV_TIME{0x80} returns
the actual convergence time before readout averaging. Range convergence and readout
averaging must be completed within the specified max convergence time.
Figure 12. Total range execution time
Table 6. Interleaved mode limits (10 Hz operation)
Parameter Period (ms)
SYSALS__INTERMEASUREMENT_PERIOD
100
Effective ALS INTERMEASUREMENT PERIOD
90
SYSRANGE__MAX_CONVERGENCE_TIME
30
Total RANGE EXECUTION TIME
35
SYSALS__INTEGRATION_TIME
50
Total ALS INTEGRATION TIME
55
TOTAL EXECUTION TIME
90
c. Default readout averaging period is calculated as follows: 1300 µs + (48 x 64.5 µs) = 4.3 ms
Readout
averaging
Range convergencePre-cal
4.3 ms
Convergence time
(variable)