VL6180 datasheet(23/73 Pages) STMICROELECTRONICS

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VL6180

Functional description

To enable the SNR check, set bit 4 in SYSRANGE__RANGE_CHECK_ENABLES (0x02D). A

lower setting results in a more aggressive filter which will result in a lower effective range but

greater accuracy. A higher setting results in a less aggressive filter which will result in a

greater effective range but lower accuracy.

The SNR value can be calculated as follows:

Note:

The SNR value is the inverse of the ambient/signal ratio limit {0x2C}.

Note:

The optimum value for SNR threshold should be determined in the final application.

2.9

Manual/autoVHV calibration

Manual/auto VHV not yet implemented in API.

SPAD(e) sensitivity is temperature dependent so VHV(f) calibration is used to regulate SPAD

sensitivity over temperature in order to minimize signal rate variation. VHV calibration is

performed either manually by the host processor or automatically by internal firmware.

Execution time is typically 200

s so has no impact on normal operation.

A VHV calibration is run once at power-up and then automatically after every N range

measurements defined by the SYSRANGE__VHV_REPEAT_RATE{0x31}register. AutoVHV

calibration is disabled by setting this register to 0. Default is 255. If autoVHV is disabled it is

recommended to run a manual VHV calibration periodically to recalibrate for any significant

temperature variation. A manual VHV calibration is performed by setting

SYSRANGE__VHV_RECALBRATE{0x2E}

to 1. This register auto-clears. This operation

should only be performed in software standby.

2.10

History buffer

History buffer not yet implemented in API.

The history buffer is a 8 x 16-bit memory which can be used to store the last 16 range

measurements (8-bit). Use of the history buffer is controlled via register

SYSTEM__HISTORY_CTRL{0x12}

. There are 3 basic functions:



enable



range selection



clear buffer

The buffer is read via eight 16-bit registers (RESULT__HISTORY_BUFFER_0{0x52} to

RESULT__HISTORY_BUFFER_7{0x60})

. The buffer holds the last 16 x 8-bit range results

as shown in Table 9.

SNR

RESULT__RANGE_RETURN_SIGNAL_COUNT{0x6C}

RESULT__RANGE_RETURN_AMB_COUNT{0x74} * 6

--------------------------------------------------------------------------------

e. Photon detectors - Single Photon Avalanche Diodes

VHV is an adjustable SPAD bias voltage and stands for Very High Voltage (typically around 14 V). Also

sometimes referred to as CP (Charge Pump).

VL6180 数据表(PDF) 23 Page - STMicroelectronics

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