The PLDRIVE box contains a group of controls which set the drive current for the VCSELs.
●Step specifies the step size in milliamps for both of the VCSEL drivers. You may select 0.5 mA,
1.0 mA, 1.5 mA, or 2.0 mA.
●LDR0 and LDR1 controls set the drive currents based on the step size. The selected step size
is multiplied by (LDRx + 1) to determine the resulting current. The current is displayed to the
right of this control. The LDRx controls have a range of 0 –15, providing a current ranging from
0.5 mA to 32 mA based on the setting of the Step control
●Each of the LDRx controls also has an associated Enable checkbox. When this box is
checked, the driver is active and will be used during prox measurements. If the box is not
checked, the driver will be disabled during prox measurements.
The PTIME control sets the rate at which each prox cycle begins when hardware averaging is
enabled. The actual time is (PTIME + 1) × 88 µs, and is displayed to the right of this control. If PTIME
is set to be less than the actual prox time (determined by PPULSE and PPULSE_LEN), the prox time
will override this value. The PTIME control can be adjusted from 0 to 255 which provides times
ranging from 88 µs to 22.528 ms.
The PWEN control enables the insertion of a wait time between normal prox integration cycles.
The PWTIME and PWLONG controls determine length of the optional prox wait time. If PWLONG is
unchecked, the prox wait time is defined as (PWTIME + 1) × 2.779 ms. If PWLONG is checked, the
wait time is multiplied by 12. PWTIME can be set from 0 to 255, providing a range from 2.779 ms to
711.424 ms. If PWLONG is enabled, this time extends from 33.348 ms to 8.537 sec.
The Binsrch Target control selects the target PDATA value that the calibration function will attempt to
reach when calibrating the prox response.
The POFFSET control sets the offset value which is used to the PDATA value to remove the effects of
electrical and system crosstalk. POFFSET is set by the device, during the calibration function, or may
be manually set to any value within a range of ±255.
Clicking on the Cal button will cause the device to perform a calibration. The device will use a binary
search method to adjust the POFFSET value so that it produces a PDATA result that is as close as
possible to the selected Binsrch Target value.
Checking the Auto Offset Adjust checkbox, will cause the device to examine every PDATA value
generated. If a PDATA value of 0 is detected, the current POFFSET value will be reduced by 1.
When Auto Offset Adjust is selected, the POFFSET control will be disabled and will be read from the
device and displayed each time it polls for the normal Prox data results.
The Auto Pulse Control (APC) function can be turned off by checking the Disable checkbox. The
APC function should normally be disabled in high crosstalk configurations.
The Prox Delay control is used along with the Prox VSYNC control to set a time delay between the
VSYNC signal and the beginning of the Prox cycle. The delay time is Prox Delay × 1.357 µs. The
value can be set from 0 to 65535 meaning the delay can be up to 88.931 ms.