void Sample_XTalkCalibrate(void) {
VL6180xDev_t myDev;
VL6180x_RangeData_t Range;
int XTalkRate;
int i, status;
/* init device */
MyDev_Init(myDev);
status = Sample_Init(myDev);
if( status <0 ){
HandleError("Sample_Init fail");
}
/* run calibration */
XTalkRate = Sample_XTalkRunCalibration(myDev);
/*TODO when possible reset re-init device else set back required scaling/filter*/
VL6180x_FilterSetState(myDev, 1); // turn on wrap around filter again
VL6180x_UpscaleSetScaling(myDev, 3); // set scaling
/* apply cross talk */
status = VL6180x_SetXTalkCompensationRate(myDev, XTalkRate);
if( status<0 ){ /* ignore warning but not error */
HandleError("VL6180x_WrWord fail");
}
for( i=0; i< 10; i++){
status = VL6180x_RangePollMeasurement(myDev, &Range);
MyDev_ShowRange(myDev, Range.range_mm);
}
}
static int stmvl6180_start(struct stmvl6180_data *data, uint8_t scaling, init_mode_e mode)
{
int rc = 0;
vl6180_dbgmsg("Enter\n");
/* Power up */
rc = data->pmodule_func_tbl->power_up(&data->client_object, &data->reset);
if (rc) {
vl6180_errmsg("%d,error rc %d\n", __LINE__, rc);
return rc;
}
/* init */
rc = stmvl6180_init_client(data);
if (rc) {
vl6180_errmsg("%d, error rc %d\n", __LINE__, rc);
data->pmodule_func_tbl->power_down(&data->client_object);
return -EINVAL;
}
/* prepare */
VL6180x_Prepare(vl6180x_dev);
VL6180x_UpscaleSetScaling(vl6180x_dev, scaling);
/* check mode */
if (mode != NORMAL_MODE) {
#if VL6180x_WRAP_AROUND_FILTER_SUPPORT
/* turn off wrap around filter */
VL6180x_FilterSetState(vl6180x_dev, 0);
#endif
VL6180x_SetXTalkCompensationRate(vl6180x_dev, 0);
VL6180x_UpdateByte(vl6180x_dev, SYSRANGE_RANGE_CHECK_ENABLES,
~RANGE_CHECK_RANGE_ENABLE_MASK, 0);
}
if (mode == OFFSETCALIB_MODE)
VL6180x_SetOffsetCalibrationData(vl6180x_dev, 0);
/* start - single shot mode */
VL6180x_RangeSetSystemMode(vl6180x_dev, MODE_START_STOP|MODE_SINGLESHOT);
data->ps_is_singleshot = 1;
data->enable_ps_sensor = 1;
/* enable work handler */
stmvl6180_schedule_handler(data);
vl6180_dbgmsg("End\n");
return rc;
}
/**
* Implement Xtalk calibration as described in VL6180x Datasheet (DocID026171 Rev 6)
*
* Device must be initialized
*
* @note device scaling wrap filter and xtalk setting are scraped !
* It is safer to reset and re init device when done
* @warning follow strictly procedure described in the device manual
* @param myDev The device
* @return The cross talk (9.7 fix point as expected in register)
*/
int Sample_XTalkRunCalibration(VL6180xDev_t myDev)
{
VL6180x_RangeData_t Range[N_MEASURE_AVG];
int32_t RangeSum;
int32_t RateSum;
int status;
int i;
int XTalkInt;
int RealTargetDistance=100;
VL6180x_UpscaleSetScaling(myDev, 1); // set scaling x1
// we do not check status as this can fail only in config that do not have configurable upscale
#if VL6180x_WRAP_AROUND_FILTER_SUPPORT
VL6180x_FilterSetState(myDev, 0); // turn off wrap around filter
#endif
status = VL6180x_ClearAllInterrupt(myDev);
if( status ){
HandleError("VL6180x_ClearAllInterrupt fail");
}
/* Ask user to place a black target at know RealTargetDistance (100mm) */
MyDev_UserWait(myDev, "Calibrating : place black target at 100mm from glass");
status=VL6180x_WrWord(myDev, SYSRANGE_CROSSTALK_COMPENSATION_RATE, 0);
for( i=0; i<N_MEASURE_AVG; i++){
status = VL6180x_RangePollMeasurement(myDev, &Range[i]);
if( status ){
HandleError("VL6180x_RangePollMeasurement fail");
}
if( Range[i].errorStatus != 0 ){
HandleError("No target detect");
}
}
RangeSum=0;
RateSum=0;
for( i=0; i<N_MEASURE_AVG; i++){
RangeSum+= Range[i].range_mm;
RateSum+= Range[i].signalRate_mcps;
}
/* Rate sum is 9.7 fixpoint so does xtlak computed below
* The order of operation is important to have decent final precision without use of floating point
* using a higher real distance and number of point may lead to 32 bit integer overflow in formula below */
XTalkInt = RateSum*(N_MEASURE_AVG*RealTargetDistance-RangeSum)/N_MEASURE_AVG /(RealTargetDistance*N_MEASURE_AVG);
MyDev_Printf(myDev, "avg range %d rate %d comp=%d\n", RangeSum/N_MEASURE_AVG, RateSum/N_MEASURE_AVG, XTalkInt);
return XTalkInt;
}