VL6180X datasheet(21/79 Pages) STMICROELECTRONICS

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VL6180X

Functional description

2.8

Range checks

Error codes 6, 8 and 11 in Table 8 are configurable by the user. They can be

enabled/disabled via register SYSRANGE__RANGE_CHECK_ENABLES{0x2D} by setting or

clearing the appropriate bit. The register default is 0x11 i,e, ECE and SNR enabled.

2.8.1

Early convergence estimate (ECE)

Early convergence estimate (ECE) is a programmable feature designed to minimize power

consumption when there is no target in the field-of-view (FOV).

The system is said to have ‘converged’ (i.e. range acquired), when the convergence

threshold(d) is reached before the max. convergence time limit (see Figure 13). This ratio

specifies the minimum return signal rate required for convergence. If there is no target in the

FOV, the system will continue to operate until the max. convergence time limit is reached

before switching off thereby consuming power. With ECE enabled, the system estimates the

Table 8. Range error codes

Bits [7:4]

Error code

Description

Range

(mm)

No error

Valid measurement

0 - 200(1)

Range overflow occurs typically around 200 mm.

1-5

System error

System error detected. No

measurement possible.

255

Early convergence estimate

ECE check failed

255

Max convergence

System did not converge before the

specified max. convergence time limit

255

Range ignore

Ignore threshold check failed

255

9-10

Not used

SNR

Ambient conditions too high.

Measurement invalidated

255

Raw range underflow

RESULT__RANGE_RAW

< 0

(because offset is programmable a

negative range result is possible)

Raw range overflow

RESULT__RANGE_RAW

is out of range.

This occurs typically around 200 mm

255

Range underflow

RESULT__RANGE_VAL

< 0

(because offset is programmable a

negative range result is possible)

Range overflow

RESULT__RANGE_VAL

is out of range.

This occurs typically around 200 mm

255

For standard ranging, the convergence threshold is set to 15360. The convergence threshold register is not

accessible by the user.

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