Diff: VL53L1X.cpp

Revision:

0:76ea242a637f

Child:

1:e54ded4af43a

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/VL53L1X.cpp	Mon Jul 30 18:45:53 2018 +0000
@@ -0,0 +1,805 @@
+// Most of the functionality of this library is based on the VL53L1X API
+// provided by ST (STSW-IMG007), and some of the explanatory comments are quoted
+// or paraphrased from the API source code, API user manual (UM2356), and
+// VL53L1X datasheet.
+
+#include "VL53L1X.h"
+#include "mbed.h"
+
+// Constructors ////////////////////////////////////////////////////////////////
+VL53L1X::VL53L1X(PinName SDA, PinName SCL) : 
+  _i2c(SDA,SCL)  
+  , io_timeout(0) // no timeout
+  , did_timeout(false)
+  , calibrated(false)
+  , saved_vhv_init(0)
+  , saved_vhv_timeout(0)
+  , distance_mode(Unknown){
+    //Set I2C fast and bring reset line high
+   _i2c.frequency(400000);
+    address = AddressDefault << 1;
+    }
+    
+/*VL53L1X::VL53L1X()
+  : address(AddressDefault)
+{
+}*/
+
+// Public Methods //////////////////////////////////////////////////////////////
+
+void VL53L1X::setAddress(uint8_t new_addr)
+{
+  writeReg(I2C_SLAVE__DEVICE_ADDRESS, new_addr & 0x7F);
+  address = new_addr;
+}
+
+// Initialize sensor using settings taken mostly from VL53L1_DataInit() and
+// VL53L1_StaticInit().
+// If io_2v8 (optional) is true or not given, the sensor is configured for 2V8
+// mode.
+bool VL53L1X::init(bool io_2v8)
+{
+  // check model ID and module type registers (values specified in datasheet)
+  int tempRegister = readReg16Bit(IDENTIFICATION__MODEL_ID);
+  printf("temporary %x\r\n", tempRegister);
+  if (tempRegister != 0xEACC) {  
+    return false; 
+  }
+
+  // VL53L1_software_reset() begin
+
+  writeReg(SOFT_RESET, 0x00);
+  wait(.001);
+  writeReg(SOFT_RESET, 0x01);
+
+  // VL53L1_poll_for_boot_completion() begin
+
+  startTimeout();
+  int firmware = (readReg(FIRMWARE__SYSTEM_STATUS));
+  printf("firmware : %x\r\n", firmware);
+  while ((readReg(FIRMWARE__SYSTEM_STATUS) & 0x01) == 0)
+  {
+    printf("stuck\r\n");
+    if (checkTimeoutExpired())
+    {
+      did_timeout = true;
+      return false;
+    }
+  }
+  // VL53L1_poll_for_boot_completion() end
+
+  // VL53L1_software_reset() end
+
+  // VL53L1_DataInit() begin
+
+  // sensor uses 1V8 mode for I/O by default; switch to 2V8 mode if necessary
+  if (io_2v8)
+  {
+    writeReg(PAD_I2C_HV__EXTSUP_CONFIG,
+      readReg(PAD_I2C_HV__EXTSUP_CONFIG) | 0x01);
+  }
+
+  // store oscillator info for later use
+  fast_osc_frequency = readReg16Bit(OSC_MEASURED__FAST_OSC__FREQUENCY);
+  osc_calibrate_val = readReg16Bit(RESULT__OSC_CALIBRATE_VAL);
+
+  // VL53L1_DataInit() end
+
+  // VL53L1_StaticInit() begin
+
+  // Note that the API does not actually apply the configuration settings below
+  // when VL53L1_StaticInit() is called: it keeps a copy of the sensor's
+  // register contents in memory and doesn't actually write them until a
+  // measurement is started. Writing the configuration here means we don't have
+  // to keep it all in memory and avoids a lot of redundant writes later.
+
+  // the API sets the preset mode to LOWPOWER_AUTONOMOUS here:
+  // VL53L1_set_preset_mode() begin
+
+  // VL53L1_preset_mode_standard_ranging() begin
+
+  // values labeled "tuning parm default" are from vl53l1_tuning_parm_defaults.h
+  // (API uses these in VL53L1_init_tuning_parm_storage_struct())
+
+  // static config
+  // API resets PAD_I2C_HV__EXTSUP_CONFIG here, but maybe we don't want to do
+  // that? (seems like it would disable 2V8 mode)
+  writeReg16Bit(DSS_CONFIG__TARGET_TOTAL_RATE_MCPS, TargetRate); // should already be this value after reset
+  writeReg(GPIO__TIO_HV_STATUS, 0x02);
+  writeReg(SIGMA_ESTIMATOR__EFFECTIVE_PULSE_WIDTH_NS, 8); // tuning parm default
+  writeReg(SIGMA_ESTIMATOR__EFFECTIVE_AMBIENT_WIDTH_NS, 16); // tuning parm default
+  writeReg(ALGO__CROSSTALK_COMPENSATION_VALID_HEIGHT_MM, 0x01);
+  writeReg(ALGO__RANGE_IGNORE_VALID_HEIGHT_MM, 0xFF);
+  writeReg(ALGO__RANGE_MIN_CLIP, 0); // tuning parm default
+  writeReg(ALGO__CONSISTENCY_CHECK__TOLERANCE, 2); // tuning parm default
+
+  // general config
+  writeReg16Bit(SYSTEM__THRESH_RATE_HIGH, 0x0000);
+  writeReg16Bit(SYSTEM__THRESH_RATE_LOW, 0x0000);
+  writeReg(DSS_CONFIG__APERTURE_ATTENUATION, 0x38);
+
+  // timing config
+  // most of these settings will be determined later by distance and timing
+  // budget configuration
+  writeReg16Bit(RANGE_CONFIG__SIGMA_THRESH, 360); // tuning parm default
+  writeReg16Bit(RANGE_CONFIG__MIN_COUNT_RATE_RTN_LIMIT_MCPS, 192); // tuning parm default
+
+  // dynamic config
+
+  writeReg(SYSTEM__GROUPED_PARAMETER_HOLD_0, 0x01);
+  writeReg(SYSTEM__GROUPED_PARAMETER_HOLD_1, 0x01);
+  writeReg(SD_CONFIG__QUANTIFIER, 2); // tuning parm default
+
+  // VL53L1_preset_mode_standard_ranging() end
+
+  // from VL53L1_preset_mode_timed_ranging_*
+  // GPH is 0 after reset, but writing GPH0 and GPH1 above seem to set GPH to 1,
+  // and things don't seem to work if we don't set GPH back to 0 (which the API
+  // does here).
+  writeReg(SYSTEM__GROUPED_PARAMETER_HOLD, 0x00);
+  writeReg(SYSTEM__SEED_CONFIG, 1); // tuning parm default
+
+  // from VL53L1_config_low_power_auto_mode
+  writeReg(SYSTEM__SEQUENCE_CONFIG, 0x8B); // VHV, PHASECAL, DSS1, RANGE
+  writeReg16Bit(DSS_CONFIG__MANUAL_EFFECTIVE_SPADS_SELECT, 200 << 8);
+  writeReg(DSS_CONFIG__ROI_MODE_CONTROL, 2); // REQUESTED_EFFFECTIVE_SPADS
+
+  // VL53L1_set_preset_mode() end
+
+  // default to long range, 50 ms timing budget
+  // note that this is different than what the API defaults to
+  setDistanceMode(Long);
+  setMeasurementTimingBudget(50000);
+
+  // VL53L1_StaticInit() end
+
+  // the API triggers this change in VL53L1_init_and_start_range() once a
+  // measurement is started; assumes MM1 and MM2 are disabled
+  writeReg16Bit(ALGO__PART_TO_PART_RANGE_OFFSET_MM,
+    readReg16Bit(MM_CONFIG__OUTER_OFFSET_MM) * 4);
+
+  return true;
+}
+
+// Write an 8-bit register
+void VL53L1X::writeReg(uint16_t registerAddr, uint8_t data)
+{
+    char data_write[3];
+    data_write[0] = (registerAddr >> 8) & 0xFF; //MSB of register address 
+    data_write[1] = registerAddr & 0xFF; //LSB of register address 
+    data_write[2] = data & 0xFF; 
+    _i2c.write(address, data_write, 3); 
+}
+ 
+void VL53L1X::writeReg16Bit(uint16_t registerAddr, uint16_t data)
+{
+    char data_write[4];
+    data_write[0] = (registerAddr >> 8) & 0xFF; //MSB of register address 
+    data_write[1] = registerAddr & 0xFF; //LSB of register address 
+    data_write[2] = (data >> 8) & 0xFF;
+    data_write[3] = data & 0xFF; 
+    _i2c.write(address, data_write, 4); 
+}
+ 
+
+// Write a 32-bit register
+void VL53L1X::writeReg32Bit(uint16_t registerAddr, uint32_t data)
+{
+    char data_write[6];
+    data_write[0] = (registerAddr >> 8) & 0xFF; //MSB of register address 
+    data_write[1] = registerAddr & 0xFF; //LSB of register address 
+    data_write[2] = (data >> 24) & 0xFF;
+    data_write[3] = (data >> 16) & 0xFF; 
+    data_write[4] = (data >> 8) & 0xFF;;
+    data_write[5] =  data & 0xFF;
+    _i2c.write(address, data_write, 6); 
+ // _i2c.beginTransmission(address);
+ /* _i2c.write((reg >> 8) & 0xFF); // reg high byte
+  _i2c.write( reg       & 0xFF); // reg low byte
+  _i2c.write((value >> 24) & 0xFF); // value highest byte
+  _i2c.write((value >> 16) & 0xFF);
+  _i2c.write((value >>  8) & 0xFF);
+  _i2c.write( value        & 0xFF); // value lowest byte
+  //last_status = _i2c.endTransmission();*/
+}
+
+// Read an 8-bit register
+uint8_t VL53L1X::readReg(uint16_t registerAddr)
+{
+  uint8_t data;
+  char data_write[2];
+  char data_read[1];
+  data_write[0] = (registerAddr >> 8) & 0xFF; //MSB of register address 
+  data_write[1] = registerAddr & 0xFF; //LSB of register address 
+  _i2c.write(address, data_write, 2,0); 
+  _i2c.read(address,data_read,1,1);
+  //Read Data from selected register
+  data=data_read[0];
+  return data;
+}
+ 
+uint16_t VL53L1X::readReg16Bit(uint16_t registerAddr)
+{
+  uint8_t data_low;
+  uint8_t data_high;
+  uint16_t data;
+ 
+  char data_write[2];
+  char data_read[2];
+  data_write[0] = (registerAddr >> 8) & 0xFF; //MSB of register address 
+  data_write[1] = registerAddr & 0xFF; //LSB of register address 
+  _i2c.write(address, data_write, 2,0); 
+  _i2c.read(address,data_read,2,1);
+  data_high = data_read[0]; //Read Data from selected register
+  data_low = data_read[1]; //Read Data from selected register
+  data = (data_high << 8)|data_low;
+ 
+  return data;
+}
+// Read a 32-bit register
+uint32_t VL53L1X::readReg32Bit(uint16_t reg)
+{
+  uint32_t value;
+/*
+  _i2c.beginTransmission(address);
+  _i2c.write((reg >> 8) & 0xFF); // reg high byte
+  _i2c.write( reg       & 0xFF); // reg low byte
+  last_status = _i2c.endTransmission();
+
+  _i2c.requestFrom(address, (uint8_t)4);
+  value  = (uint32_t)_i2c.read() << 24; // value highest byte
+  value |= (uint32_t)_i2c.read() << 16;
+  value |= (uint16_t)_i2c.read() <<  8;
+  value |=           _i2c.read();       // value lowest byte
+*/
+  return value;
+}
+
+// set distance mode to Short, Medium, or Long
+// based on VL53L1_SetDistanceMode()
+bool VL53L1X::setDistanceMode(DistanceMode mode)
+{
+  // save existing timing budget
+  uint32_t budget_us = getMeasurementTimingBudget();
+  printf("budget_us = %d", budget_us);
+  switch (mode)
+  {
+    case Short:
+      // from VL53L1_preset_mode_standard_ranging_short_range()
+
+      // timing config
+      writeReg(RANGE_CONFIG__VCSEL_PERIOD_A, 0x07);
+      writeReg(RANGE_CONFIG__VCSEL_PERIOD_B, 0x05);
+      writeReg(RANGE_CONFIG__VALID_PHASE_HIGH, 0x38);
+
+      // dynamic config
+      writeReg(SD_CONFIG__WOI_SD0, 0x07);
+      writeReg(SD_CONFIG__WOI_SD1, 0x05);
+      writeReg(SD_CONFIG__INITIAL_PHASE_SD0, 6); // tuning parm default
+      writeReg(SD_CONFIG__INITIAL_PHASE_SD1, 6); // tuning parm default
+
+      break;
+
+    case Medium:
+      // from VL53L1_preset_mode_standard_ranging()
+
+      // timing config
+      writeReg(RANGE_CONFIG__VCSEL_PERIOD_A, 0x0B);
+      writeReg(RANGE_CONFIG__VCSEL_PERIOD_B, 0x09);
+      writeReg(RANGE_CONFIG__VALID_PHASE_HIGH, 0x78);
+
+      // dynamic config
+      writeReg(SD_CONFIG__WOI_SD0, 0x0B);
+      writeReg(SD_CONFIG__WOI_SD1, 0x09);
+      writeReg(SD_CONFIG__INITIAL_PHASE_SD0, 10); // tuning parm default
+      writeReg(SD_CONFIG__INITIAL_PHASE_SD1, 10); // tuning parm default
+
+      break;
+
+    case Long: // long
+      // from VL53L1_preset_mode_standard_ranging_long_range()
+
+      // timing config
+      writeReg(RANGE_CONFIG__VCSEL_PERIOD_A, 0x0F);
+      writeReg(RANGE_CONFIG__VCSEL_PERIOD_B, 0x0D);
+      writeReg(RANGE_CONFIG__VALID_PHASE_HIGH, 0xB8);
+
+      // dynamic config
+      writeReg(SD_CONFIG__WOI_SD0, 0x0F);
+      writeReg(SD_CONFIG__WOI_SD1, 0x0D);
+      writeReg(SD_CONFIG__INITIAL_PHASE_SD0, 14); // tuning parm default
+      writeReg(SD_CONFIG__INITIAL_PHASE_SD1, 14); // tuning parm default
+
+      break;
+
+    default:
+      // unrecognized mode - do nothing
+      return false;
+  }
+
+  // reapply timing budget
+  setMeasurementTimingBudget(budget_us);
+
+  // save mode so it can be returned by getDistanceMode()
+  distance_mode = mode;
+
+  return true;
+}
+
+// Set the measurement timing budget in microseconds, which is the time allowed
+// for one measurement. A longer timing budget allows for more accurate
+// measurements.
+// based on VL53L1_SetMeasurementTimingBudgetMicroSeconds()
+bool VL53L1X::setMeasurementTimingBudget(uint32_t budget_us)
+{
+  // assumes PresetMode is LOWPOWER_AUTONOMOUS
+
+  if (budget_us <= TimingGuard) { return false; }
+
+  uint32_t range_config_timeout_us = budget_us -= TimingGuard;
+  if (range_config_timeout_us > 1100000) { return false; } // FDA_MAX_TIMING_BUDGET_US * 2
+
+  range_config_timeout_us /= 2;
+
+  // VL53L1_calc_timeout_register_values() begin
+
+  uint32_t macro_period_us;
+
+  // "Update Macro Period for Range A VCSEL Period"
+  macro_period_us = calcMacroPeriod(readReg(RANGE_CONFIG__VCSEL_PERIOD_A));
+
+  // "Update Phase timeout - uses Timing A"
+  // Timeout of 1000 is tuning parm default (TIMED_PHASECAL_CONFIG_TIMEOUT_US_DEFAULT)
+  // via VL53L1_get_preset_mode_timing_cfg().
+  uint32_t phasecal_timeout_mclks = timeoutMicrosecondsToMclks(1000, macro_period_us);
+  if (phasecal_timeout_mclks > 0xFF) { phasecal_timeout_mclks = 0xFF; }
+  writeReg(PHASECAL_CONFIG__TIMEOUT_MACROP, phasecal_timeout_mclks);
+
+  // "Update MM Timing A timeout"
+  // Timeout of 1 is tuning parm default (LOWPOWERAUTO_MM_CONFIG_TIMEOUT_US_DEFAULT)
+  // via VL53L1_get_preset_mode_timing_cfg(). With the API, the register
+  // actually ends up with a slightly different value because it gets assigned,
+  // retrieved, recalculated with a different macro period, and reassigned,
+  // but it probably doesn't matter because it seems like the MM ("mode
+  // mitigation"?) sequence steps are disabled in low power auto mode anyway.
+  writeReg16Bit(MM_CONFIG__TIMEOUT_MACROP_A, encodeTimeout(
+    timeoutMicrosecondsToMclks(1, macro_period_us)));
+
+  // "Update Range Timing A timeout"
+  writeReg16Bit(RANGE_CONFIG__TIMEOUT_MACROP_A, encodeTimeout(
+    timeoutMicrosecondsToMclks(range_config_timeout_us, macro_period_us)));
+
+  // "Update Macro Period for Range B VCSEL Period"
+  macro_period_us = calcMacroPeriod(readReg(RANGE_CONFIG__VCSEL_PERIOD_B));
+
+  // "Update MM Timing B timeout"
+  // (See earlier comment about MM Timing A timeout.)
+  writeReg16Bit(MM_CONFIG__TIMEOUT_MACROP_B, encodeTimeout(
+    timeoutMicrosecondsToMclks(1, macro_period_us)));
+
+  // "Update Range Timing B timeout"
+  writeReg16Bit(RANGE_CONFIG__TIMEOUT_MACROP_B, encodeTimeout(
+    timeoutMicrosecondsToMclks(range_config_timeout_us, macro_period_us)));
+    printf("it is true\r\n");
+  // VL53L1_calc_timeout_register_values() end
+
+  return true;
+}
+
+// Get the measurement timing budget in microseconds
+// based on VL53L1_SetMeasurementTimingBudgetMicroSeconds()
+uint32_t VL53L1X::getMeasurementTimingBudget()
+{
+  // assumes PresetMode is LOWPOWER_AUTONOMOUS and these sequence steps are
+  // enabled: VHV, PHASECAL, DSS1, RANGE
+
+  // VL53L1_get_timeouts_us() begin
+
+  // "Update Macro Period for Range A VCSEL Period"
+  uint32_t macro_period_us = calcMacroPeriod(readReg(RANGE_CONFIG__VCSEL_PERIOD_A));
+
+  // "Get Range Timing A timeout"
+
+  uint32_t range_config_timeout_us = timeoutMclksToMicroseconds(decodeTimeout(
+    readReg16Bit(RANGE_CONFIG__TIMEOUT_MACROP_A)), macro_period_us);
+
+  // VL53L1_get_timeouts_us() end
+
+  return  2 * range_config_timeout_us + TimingGuard;
+}
+
+// Start continuous ranging measurements, with the given inter-measurement
+// period in milliseconds determining how often the sensor takes a measurement.
+void VL53L1X::startContinuous(uint32_t period_ms)
+{
+  // from VL53L1_set_inter_measurement_period_ms()
+  writeReg32Bit(SYSTEM__INTERMEASUREMENT_PERIOD, period_ms * osc_calibrate_val);
+  writeReg(SYSTEM__INTERRUPT_CLEAR, 0x01); // sys_interrupt_clear_range
+  writeReg(SYSTEM__MODE_START, 0x40); // mode_range__timed
+}
+
+// Stop continuous measurements
+// based on VL53L1_stop_range()
+void VL53L1X::stopContinuous()
+{
+  writeReg(SYSTEM__MODE_START, 0x80); // mode_range__abort
+
+  // VL53L1_low_power_auto_data_stop_range() begin
+
+  calibrated = false;
+
+  // "restore vhv configs"
+  if (saved_vhv_init != 0)
+  {
+    writeReg(VHV_CONFIG__INIT, saved_vhv_init);
+  }
+  if (saved_vhv_timeout != 0)
+  {
+     writeReg(VHV_CONFIG__TIMEOUT_MACROP_LOOP_BOUND, saved_vhv_timeout);
+  }
+
+  // "remove phasecal override"
+  writeReg(PHASECAL_CONFIG__OVERRIDE, 0x00);
+
+  // VL53L1_low_power_auto_data_stop_range() end
+}
+
+// Returns a range reading in millimeters when continuous mode is active
+// (readRangeSingleMillimeters() also calls this function after starting a
+// single-shot range measurement)
+uint16_t VL53L1X::read(bool blocking)
+{
+  if (blocking)
+  {
+    startTimeout();
+    while (dataReady())
+    {
+      if (checkTimeoutExpired())
+      {
+        did_timeout = true;
+        ranging_data.range_status = None;
+        ranging_data.range_mm = 0;
+        ranging_data.peak_signal_count_rate_MCPS = 0;
+        ranging_data.ambient_count_rate_MCPS = 0;
+        return ranging_data.range_mm;
+      }
+    }
+  }
+
+  readResults();
+
+  if (!calibrated)
+  {
+    setupManualCalibration();
+    calibrated = true;
+  }
+
+  updateDSS();
+
+  getRangingData();
+
+  writeReg(SYSTEM__INTERRUPT_CLEAR, 0x01); // sys_interrupt_clear_range
+
+  return ranging_data.range_mm;
+}
+
+// convert a RangeStatus to a readable string
+// Note that on an AVR, these strings are stored in RAM (dynamic memory), which
+// makes working with them easier but uses up 200+ bytes of RAM (many AVR-based
+// Arduinos only have about 2000 bytes of RAM). You can avoid this memory usage
+// if you do not call this function in your sketch.
+const char * VL53L1X::rangeStatusToString(RangeStatus status)
+{
+  switch (status)
+  {
+    case RangeValid:
+      return "range valid";
+
+    case SigmaFail:
+      return "sigma fail";
+
+    case SignalFail:
+      return "signal fail";
+
+    case RangeValidMinRangeClipped:
+      return "range valid, min range clipped";
+
+    case OutOfBoundsFail:
+      return "out of bounds fail";
+
+    case HardwareFail:
+      return "hardware fail";
+
+    case RangeValidNoWrapCheckFail:
+      return "range valid, no wrap check fail";
+
+    case WrapTargetFail:
+      return "wrap target fail";
+
+    case XtalkSignalFail:
+      return "xtalk signal fail";
+
+    case SynchronizationInt:
+      return "synchronization int";
+
+    case MinRangeFail:
+      return "min range fail";
+
+    case None:
+      return "no update";
+
+    default:
+      return "unknown status";
+  }
+}
+
+// Did a timeout occur in one of the read functions since the last call to
+// timeoutOccurred()?
+bool VL53L1X::timeoutOccurred()
+{
+  bool tmp = did_timeout;
+  did_timeout = false;
+  return tmp;
+}
+
+// Private Methods /////////////////////////////////////////////////////////////
+
+// "Setup ranges after the first one in low power auto mode by turning off
+// FW calibration steps and programming static values"
+// based on VL53L1_low_power_auto_setup_manual_calibration()
+void VL53L1X::setupManualCalibration()
+{
+  // "save original vhv configs"
+  saved_vhv_init = readReg(VHV_CONFIG__INIT);
+  saved_vhv_timeout = readReg(VHV_CONFIG__TIMEOUT_MACROP_LOOP_BOUND);
+
+  // "disable VHV init"
+  writeReg(VHV_CONFIG__INIT, saved_vhv_init & 0x7F);
+
+  // "set loop bound to tuning param"
+  writeReg(VHV_CONFIG__TIMEOUT_MACROP_LOOP_BOUND,
+    (saved_vhv_timeout & 0x03) + (3 << 2)); // tuning parm default (LOWPOWERAUTO_VHV_LOOP_BOUND_DEFAULT)
+
+  // "override phasecal"
+  writeReg(PHASECAL_CONFIG__OVERRIDE, 0x01);
+  writeReg(CAL_CONFIG__VCSEL_START, readReg(PHASECAL_RESULT__VCSEL_START));
+}
+
+// read measurement results into buffer
+void VL53L1X::readResults()
+{
+//  char infoToWrite[2];
+  char infoToRead[17];
+  //_i2c.beginTransmission(address);
+  _i2c.write((RESULT__RANGE_STATUS >> 8) & 0xFF); // reg high byte
+  _i2c.write( RESULT__RANGE_STATUS       & 0xFF); // reg low byte
+//  last_status = _i2c.endTransmission();
+
+//  _i2c.requestFrom(address, (uint8_t)17);
+  _i2c.read(address, infoToRead, 17, 0);
+
+  results.range_status = infoToRead[0];
+
+//  infoToRead[1]; // report_status: not used
+
+  results.stream_count = infoToRead[2];
+
+  results.dss_actual_effective_spads_sd0  = (uint16_t)infoToRead[3] << 8; // high byte
+  results.dss_actual_effective_spads_sd0 |=           infoToRead[4];      // low byte
+
+//  infoToRead[5]; // peak_signal_count_rate_mcps_sd0: not used
+//  infoToRead[6];
+
+  results.ambient_count_rate_mcps_sd0  = (uint16_t)infoToRead[7] << 8; // high byte
+  results.ambient_count_rate_mcps_sd0 |=           infoToRead[8];      // low byte
+
+//  infoToRead[9]; // sigma_sd0: not used
+//  infoToRead[10];
+
+//  infoToRead[11]; // phase_sd0: not used
+//  infoToRead[12];
+
+  results.final_crosstalk_corrected_range_mm_sd0  = (uint16_t)infoToRead[13] << 8; // high byte
+  results.final_crosstalk_corrected_range_mm_sd0 |=           infoToRead[14];      // low byte
+
+  results.peak_signal_count_rate_crosstalk_corrected_mcps_sd0  = (uint16_t)infoToRead[15] << 8; // high byte
+  results.peak_signal_count_rate_crosstalk_corrected_mcps_sd0 |=           infoToRead[16];      // low byte
+}
+
+// perform Dynamic SPAD Selection calculation/update
+// based on VL53L1_low_power_auto_update_DSS()
+void VL53L1X::updateDSS()
+{
+  uint16_t spadCount = results.dss_actual_effective_spads_sd0;
+
+  if (spadCount != 0)
+  {
+    // "Calc total rate per spad"
+
+    uint32_t totalRatePerSpad =
+      (uint32_t)results.peak_signal_count_rate_crosstalk_corrected_mcps_sd0 +
+      results.ambient_count_rate_mcps_sd0;
+
+    // "clip to 16 bits"
+    if (totalRatePerSpad > 0xFFFF) { totalRatePerSpad = 0xFFFF; }
+
+    // "shift up to take advantage of 32 bits"
+    totalRatePerSpad <<= 16;
+
+    totalRatePerSpad /= spadCount;
+
+    if (totalRatePerSpad != 0)
+    {
+      // "get the target rate and shift up by 16"
+      uint32_t requiredSpads = ((uint32_t)TargetRate << 16) / totalRatePerSpad;
+
+      // "clip to 16 bit"
+      if (requiredSpads > 0xFFFF) { requiredSpads = 0xFFFF; }
+
+      // "override DSS config"
+      writeReg16Bit(DSS_CONFIG__MANUAL_EFFECTIVE_SPADS_SELECT, requiredSpads);
+      // DSS_CONFIG__ROI_MODE_CONTROL should already be set to REQUESTED_EFFFECTIVE_SPADS
+
+      return;
+    }
+  }
+
+  // If we reached this point, it means something above would have resulted in a
+  // divide by zero.
+  // "We want to gracefully set a spad target, not just exit with an error"
+
+   // "set target to mid point"
+   writeReg16Bit(DSS_CONFIG__MANUAL_EFFECTIVE_SPADS_SELECT, 0x8000);
+}
+
+// get range, status, rates from results buffer
+// based on VL53L1_GetRangingMeasurementData()
+void VL53L1X::getRangingData()
+{
+  // VL53L1_copy_sys_and_core_results_to_range_results() begin
+
+  uint16_t range = results.final_crosstalk_corrected_range_mm_sd0;
+
+  // "apply correction gain"
+  // gain factor of 2011 is tuning parm default (VL53L1_TUNINGPARM_LITE_RANGING_GAIN_FACTOR_DEFAULT)
+  // Basically, this appears to scale the result by 2011/2048, or about 98%
+  // (with the 1024 added for proper rounding).
+  ranging_data.range_mm = ((uint32_t)range * 2011 + 0x0400) / 0x0800;
+
+  // VL53L1_copy_sys_and_core_results_to_range_results() end
+
+  // set range_status in ranging_data based on value of RESULT__RANGE_STATUS register
+  // mostly based on ConvertStatusLite()
+  switch(results.range_status)
+  {
+    case 17: // MULTCLIPFAIL
+    case 2: // VCSELWATCHDOGTESTFAILURE
+    case 1: // VCSELCONTINUITYTESTFAILURE
+    case 3: // NOVHVVALUEFOUND
+      // from SetSimpleData()
+      ranging_data.range_status = HardwareFail;
+      break;
+
+    case 13: // USERROICLIP
+     // from SetSimpleData()
+      ranging_data.range_status = MinRangeFail;
+      break;
+
+    case 18: // GPHSTREAMCOUNT0READY
+      ranging_data.range_status = SynchronizationInt;
+      break;
+
+    case 5: // RANGEPHASECHECK
+      ranging_data.range_status =  OutOfBoundsFail;
+      break;
+
+    case 4: // MSRCNOTARGET
+      ranging_data.range_status = SignalFail;
+      break;
+
+    case 6: // SIGMATHRESHOLDCHECK
+      ranging_data.range_status = SignalFail;
+      break;
+
+    case 7: // PHASECONSISTENCY
+      ranging_data.range_status = WrapTargetFail;
+      break;
+
+    case 12: // RANGEIGNORETHRESHOLD
+      ranging_data.range_status = XtalkSignalFail;
+      break;
+
+    case 8: // MINCLIP
+      ranging_data.range_status = RangeValidMinRangeClipped;
+      break;
+
+    case 9: // RANGECOMPLETE
+      // from VL53L1_copy_sys_and_core_results_to_range_results()
+      if (results.stream_count == 0)
+      {
+        ranging_data.range_status = RangeValidNoWrapCheckFail;
+      }
+      else
+      {
+        ranging_data.range_status = RangeValid;
+      }
+      break;
+
+    default:
+      ranging_data.range_status = None;
+  }
+
+  // from SetSimpleData()
+  ranging_data.peak_signal_count_rate_MCPS =
+    countRateFixedToFloat(results.peak_signal_count_rate_crosstalk_corrected_mcps_sd0);
+  ranging_data.ambient_count_rate_MCPS =
+    countRateFixedToFloat(results.ambient_count_rate_mcps_sd0);
+}
+
+// Decode sequence step timeout in MCLKs from register value
+// based on VL53L1_decode_timeout()
+uint32_t VL53L1X::decodeTimeout(uint16_t reg_val)
+{
+  return ((uint32_t)(reg_val & 0xFF) << (reg_val >> 8)) + 1;
+}
+
+// Encode sequence step timeout register value from timeout in MCLKs
+// based on VL53L1_encode_timeout()
+uint16_t VL53L1X::encodeTimeout(uint32_t timeout_mclks)
+{
+  // encoded format: "(LSByte * 2^MSByte) + 1"
+
+  uint32_t ls_byte = 0;
+  uint16_t ms_byte = 0;
+
+  if (timeout_mclks > 0)
+  {
+    ls_byte = timeout_mclks - 1;
+
+    while ((ls_byte & 0xFFFFFF00) > 0)
+    {
+      ls_byte >>= 1;
+      ms_byte++;
+    }
+
+    return (ms_byte << 8) | (ls_byte & 0xFF);
+  }
+  else { return 0; }
+}
+
+// Convert sequence step timeout from macro periods to microseconds with given
+// macro period in microseconds (12.12 format)
+// based on VL53L1_calc_timeout_us()
+uint32_t VL53L1X::timeoutMclksToMicroseconds(uint32_t timeout_mclks, uint32_t macro_period_us)
+{
+  return ((uint64_t)timeout_mclks * macro_period_us + 0x800) >> 12;
+}
+
+// Convert sequence step timeout from microseconds to macro periods with given
+// macro period in microseconds (12.12 format)
+// based on VL53L1_calc_timeout_mclks()
+uint32_t VL53L1X::timeoutMicrosecondsToMclks(uint32_t timeout_us, uint32_t macro_period_us)
+{
+  return (((uint32_t)timeout_us << 12) + (macro_period_us >> 1)) / macro_period_us;
+}
+
+// Calculate macro period in microseconds (12.12 format) with given VCSEL period
+// assumes fast_osc_frequency has been read and stored
+// based on VL53L1_calc_macro_period_us()
+uint32_t VL53L1X::calcMacroPeriod(uint8_t vcsel_period)
+{
+  // from VL53L1_calc_pll_period_us()
+  // fast osc frequency in 4.12 format; PLL period in 0.24 format
+  uint32_t pll_period_us = ((uint32_t)0x01 << 30) / fast_osc_frequency;
+
+  // from VL53L1_decode_vcsel_period()
+  uint8_t vcsel_period_pclks = (vcsel_period + 1) << 1;
+
+  // VL53L1_MACRO_PERIOD_VCSEL_PERIODS = 2304
+  uint32_t macro_period_us = (uint32_t)2304 * pll_period_us;
+  macro_period_us >>= 6;
+  macro_period_us *= vcsel_period_pclks;
+  macro_period_us >>= 6;
+
+  return macro_period_us;
+}
\ No newline at end of file