Modified from arduino library https://github.com/pololu/vl53l0x-arduino

Dependencies:   mbed

Files at this revision

API Documentation at this revision

Comitter:
open4416
Date:
Thu Feb 16 08:45:17 2017 +0000
Commit message:
works fine on STM32 without state check but high speed ; >200Hz

Changed in this revision

VL53L0X_SH.cpp Show annotated file Show diff for this revision Revisions of this file
VL53L0X_SH.h Show annotated file Show diff for this revision Revisions of this file
main.cpp Show annotated file Show diff for this revision Revisions of this file
mbed.bld Show annotated file Show diff for this revision Revisions of this file
diff -r 000000000000 -r d738e3a03cf8 VL53L0X_SH.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/VL53L0X_SH.cpp	Thu Feb 16 08:45:17 2017 +0000
@@ -0,0 +1,983 @@
+// Most of the functionality of this library is based on the VL53L0X API
+// provided by ST (STSW-IMG005), and some of the explanatory comments are quoted
+// or paraphrased from the API source code, API user manual (UM2039), and the
+// VL53L0X datasheet.
+
+#include <VL53L0X_SH.h>
+#include "mbed.h"
+// Defines /////////////////////////////////////////////////////////////////////
+
+// The Arduino two-wire interface uses a 7-bit number for the address,
+// and sets the last bit correctly based on reads and writes
+#define ADDRESS_DEFAULT 0b0101001
+
+// Record the current time to check an upcoming timeout against
+//#define startTimeout() (timeout_start_ms = millis())
+
+// Check if timeout is enabled (set to nonzero value) and has expired
+//#define checkTimeoutExpired() (io_timeout > 0 && ((short)millis() - timeout_start_ms) > io_timeout)
+
+// Decode VCSEL (vertical cavity surface emitting laser) pulse period in PCLKs
+// from register value
+// based on VL53L0X_decode_vcsel_period()
+#define decodeVcselPeriod(reg_val)      (((reg_val) + 1) << 1)
+
+// Encode VCSEL pulse period register value from period in PCLKs
+// based on VL53L0X_encode_vcsel_period()
+#define encodeVcselPeriod(period_pclks) (((period_pclks) >> 1) - 1)
+
+// Calculate macro period in *nanoseconds* from VCSEL period in PCLKs
+// based on VL53L0X_calc_macro_period_ps()
+// PLL_period_ps = 1655; macro_period_vclks = 2304
+#define calcMacroPeriod(vcsel_period_pclks) ((((long)2304 * (vcsel_period_pclks) * 1655) + 500) / 1000)
+
+// Constructors ////////////////////////////////////////////////////////////////
+I2C         i2c(D14, D15);      //I2C reg(SDA, SCL)
+
+VL53L0X::VL53L0X(void)
+    : address(ADDRESS_DEFAULT)
+    , io_timeout(0) // no timeout
+    , did_timeout(false)
+{
+}
+
+// Public Methods //////////////////////////////////////////////////////////////
+
+void VL53L0X::setAddress(char new_addr)
+{
+    writeReg(I2C_SLAVE_DEVICE_ADDRESS, new_addr & 0x7F);
+    address = new_addr;
+}
+
+// Initialize sensor using sequence based on VL53L0X_DataInit(),
+// VL53L0X_StaticInit(), and VL53L0X_PerformRefCalibration().
+// This function does not perform reference SPAD calibration
+// (VL53L0X_PerformRefSpadManagement()), since the API user manual says that it
+// is performed by ST on the bare modules; it seems like that should work well
+// enough unless a cover glass is added.
+// If io_2v8 (optional) is true or not given, the sensor is configured for 2V8
+// mode.
+bool VL53L0X::init(bool io_2v8)
+{
+    if (io_2v8) {
+        writeReg(VHV_CONFIG_PAD_SCL_SDA__EXTSUP_HV,
+                 readReg(VHV_CONFIG_PAD_SCL_SDA__EXTSUP_HV) | 0x01); // set bit 0
+    }
+    // "Set I2C standard mode"
+    writeReg(0x88, 0x00);
+    writeReg(0x80, 0x01);
+    writeReg(0xFF, 0x01);
+    writeReg(0x00, 0x00);
+    stop_variable = readReg(0x91);
+    writeReg(0x00, 0x01);
+    writeReg(0xFF, 0x00);
+    writeReg(0x80, 0x00);
+
+    // disable SIGNAL_RATE_MSRC (bit 1) and SIGNAL_RATE_PRE_RANGE (bit 4) limit checks
+    writeReg(MSRC_CONFIG_CONTROL, readReg(MSRC_CONFIG_CONTROL) | 0x12);
+
+    // set final range signal rate limit to 0.25 MCPS (million counts per second)
+    setSignalRateLimit(0.25);
+
+    writeReg(SYSTEM_SEQUENCE_CONFIG, 0xFF);
+
+    // VL53L0X_DataInit() end
+
+    // VL53L0X_StaticInit() begin
+
+    char spad_count;
+    bool spad_type_is_aperture;
+    if (!getSpadInfo(&spad_count, &spad_type_is_aperture)) {
+        return false;
+    }
+
+    // The SPAD map (RefGoodSpadMap) is read by VL53L0X_get_info_from_device() in
+    // the API, but the same data seems to be more easily readable from
+    // GLOBAL_CONFIG_SPAD_ENABLES_REF_0 through _6, so read it from there
+    char ref_spad_map[6];
+    readMulti(GLOBAL_CONFIG_SPAD_ENABLES_REF_0, ref_spad_map, 6);
+
+    // -- VL53L0X_set_reference_spads() begin (assume NVM values are valid)
+
+    writeReg(0xFF, 0x01);
+    writeReg(DYNAMIC_SPAD_REF_EN_START_OFFSET, 0x00);
+    writeReg(DYNAMIC_SPAD_NUM_REQUESTED_REF_SPAD, 0x2C);
+    writeReg(0xFF, 0x00);
+    writeReg(GLOBAL_CONFIG_REF_EN_START_SELECT, 0xB4);
+
+    char first_spad_to_enable = spad_type_is_aperture ? 12 : 0; // 12 is the first aperture spad
+    char spads_enabled = 0;
+
+    for (char i = 0; i < 48; i++) {
+        if (i < first_spad_to_enable || spads_enabled == spad_count) {
+            // This bit is lower than the first one that should be enabled, or
+            // (reference_spad_count) bits have already been enabled, so zero this bit
+            ref_spad_map[i / 8] &= ~(1 << (i % 8));
+        } else if ((ref_spad_map[i / 8] >> (i % 8)) & 0x1) {
+            spads_enabled++;
+        }
+    }
+
+    writeMulti(GLOBAL_CONFIG_SPAD_ENABLES_REF_0, ref_spad_map, 6);
+
+    // -- VL53L0X_set_reference_spads() end
+
+    // -- VL53L0X_load_tuning_settings() begin
+    // DefaultTuningSettings from vl53l0x_tuning.h
+
+    writeReg(0xFF, 0x01);
+    writeReg(0x00, 0x00);
+
+    writeReg(0xFF, 0x00);
+    writeReg(0x09, 0x00);
+    writeReg(0x10, 0x00);
+    writeReg(0x11, 0x00);
+
+    writeReg(0x24, 0x01);
+    writeReg(0x25, 0xFF);
+    writeReg(0x75, 0x00);
+
+    writeReg(0xFF, 0x01);
+    writeReg(0x4E, 0x2C);
+    writeReg(0x48, 0x00);
+    writeReg(0x30, 0x20);
+
+    writeReg(0xFF, 0x00);
+    writeReg(0x30, 0x09);
+    writeReg(0x54, 0x00);
+    writeReg(0x31, 0x04);
+    writeReg(0x32, 0x03);
+    writeReg(0x40, 0x83);
+    writeReg(0x46, 0x25);
+    writeReg(0x60, 0x00);
+    writeReg(0x27, 0x00);
+    writeReg(0x50, 0x06);
+    writeReg(0x51, 0x00);
+    writeReg(0x52, 0x96);
+    writeReg(0x56, 0x08);
+    writeReg(0x57, 0x30);
+    writeReg(0x61, 0x00);
+    writeReg(0x62, 0x00);
+    writeReg(0x64, 0x00);
+    writeReg(0x65, 0x00);
+    writeReg(0x66, 0xA0);
+
+    writeReg(0xFF, 0x01);
+    writeReg(0x22, 0x32);
+    writeReg(0x47, 0x14);
+    writeReg(0x49, 0xFF);
+    writeReg(0x4A, 0x00);
+
+    writeReg(0xFF, 0x00);
+    writeReg(0x7A, 0x0A);
+    writeReg(0x7B, 0x00);
+    writeReg(0x78, 0x21);
+
+    writeReg(0xFF, 0x01);
+    writeReg(0x23, 0x34);
+    writeReg(0x42, 0x00);
+    writeReg(0x44, 0xFF);
+    writeReg(0x45, 0x26);
+    writeReg(0x46, 0x05);
+    writeReg(0x40, 0x40);
+    writeReg(0x0E, 0x06);
+    writeReg(0x20, 0x1A);
+    writeReg(0x43, 0x40);
+
+    writeReg(0xFF, 0x00);
+    writeReg(0x34, 0x03);
+    writeReg(0x35, 0x44);
+
+    writeReg(0xFF, 0x01);
+    writeReg(0x31, 0x04);
+    writeReg(0x4B, 0x09);
+    writeReg(0x4C, 0x05);
+    writeReg(0x4D, 0x04);
+
+    writeReg(0xFF, 0x00);
+    writeReg(0x44, 0x00);
+    writeReg(0x45, 0x20);
+    writeReg(0x47, 0x08);
+    writeReg(0x48, 0x28);
+    writeReg(0x67, 0x00);
+    writeReg(0x70, 0x04);
+    writeReg(0x71, 0x01);
+    writeReg(0x72, 0xFE);
+    writeReg(0x76, 0x00);
+    writeReg(0x77, 0x00);
+
+    writeReg(0xFF, 0x01);
+    writeReg(0x0D, 0x01);
+
+    writeReg(0xFF, 0x00);
+    writeReg(0x80, 0x01);
+    writeReg(0x01, 0xF8);
+
+    writeReg(0xFF, 0x01);
+    writeReg(0x8E, 0x01);
+    writeReg(0x00, 0x01);
+    writeReg(0xFF, 0x00);
+    writeReg(0x80, 0x00);
+
+    // -- VL53L0X_load_tuning_settings() end
+
+    // "Set interrupt config to new sample ready"
+    // -- VL53L0X_SetGpioConfig() begin
+
+    writeReg(SYSTEM_INTERRUPT_CONFIG_GPIO, 0x04);
+    writeReg(GPIO_HV_MUX_ACTIVE_HIGH, readReg(GPIO_HV_MUX_ACTIVE_HIGH) & ~0x10); // active low
+    writeReg(SYSTEM_INTERRUPT_CLEAR, 0x01);
+
+    // -- VL53L0X_SetGpioConfig() end
+
+    measurement_timing_budget_us = getMeasurementTimingBudget();
+
+    // "Disable MSRC and TCC by default"
+    // MSRC = Minimum Signal Rate Check
+    // TCC = Target CentreCheck
+    // -- VL53L0X_SetSequenceStepEnable() begin
+
+    writeReg(SYSTEM_SEQUENCE_CONFIG, 0xE8);
+
+    // -- VL53L0X_SetSequenceStepEnable() end
+
+    // "Recalculate timing budget"
+    setMeasurementTimingBudget(measurement_timing_budget_us);
+
+    // VL53L0X_StaticInit() end
+
+    // VL53L0X_PerformRefCalibration() begin (VL53L0X_perform_ref_calibration())
+
+    // -- VL53L0X_perform_vhv_calibration() begin
+
+    writeReg(SYSTEM_SEQUENCE_CONFIG, 0x01);
+    if (!performSingleRefCalibration(0x40)) {
+        return false;
+    }
+
+    // -- VL53L0X_perform_vhv_calibration() end
+
+    // -- VL53L0X_perform_phase_calibration() begin
+
+    writeReg(SYSTEM_SEQUENCE_CONFIG, 0x02);
+    if (!performSingleRefCalibration(0x00)) {
+        return false;
+    }
+
+    // -- VL53L0X_perform_phase_calibration() end
+
+    // "restore the previous Sequence Config"
+    writeReg(SYSTEM_SEQUENCE_CONFIG, 0xE8);
+
+    // VL53L0X_PerformRefCalibration() end
+
+    return true;
+}
+
+// Write an 8-bit register
+void VL53L0X::writeReg(char reg, char value)
+{
+    data_w_2[0] = reg;
+    data_w_2[1] = value;
+    i2c.write( address<<1 | 0x00, data_w_2, 2, 0);
+}
+
+// Write a 16-bit register
+void VL53L0X::writeReg16Bit(char reg, short value)
+{
+    data_w_3[0] = reg;
+    data_w_3[1] = (value >> 8) & 0xFF;
+    data_w_3[2] = (value     ) & 0xFF;
+    i2c.write( address<<1 | 0x00, data_w_3, 3, 0);
+}
+
+// Write a 32-bit register
+void VL53L0X::writeReg32Bit(char reg, long value)
+{
+    data_w_5[0] = reg;
+    data_w_5[1] = (value >> 24) & 0xFF;
+    data_w_5[2] = (value >> 16) & 0xFF;
+    data_w_5[3] = (value >>  8) & 0xFF;
+    data_w_5[4] = (value      ) & 0xFF;
+    i2c.write( address<<1 | 0x00, data_w_5, 5, 0);
+}
+
+// Read an 8-bit register
+char VL53L0X::readReg(char reg)
+{
+    char value[1];
+    data_r_1[0] = reg;
+    i2c.write( address<<1 | 0x00, data_r_1, 1, 0);
+    i2c.read ( address<<1 | 0x01, value, 1, 0);
+    return value[0];
+}
+
+// Read a 16-bit register
+short VL53L0X::readReg16Bit(char reg)
+{
+    short value;
+    data_r_1[0] = reg;
+    i2c.write( address<<1 | 0x00, data_r_1, 1, 0);
+    i2c.read ( address<<1 | 0x01, data_r_2, 2, 0);
+    value = data_r_2[0] << 8 | data_r_2[1];
+    return value;
+}
+
+// Read a 32-bit register
+long VL53L0X::readReg32Bit(char reg)
+{
+    long value;
+    data_r_1[0] = reg;
+    i2c.write( address<<1 | 0x00, data_r_1, 1, 0);
+    i2c.read ( address<<1 | 0x01, data_r_4, 4, 0);
+    value  = data_r_4[0] << 24;
+    value |= data_r_4[1] << 16;
+    value |= data_r_4[2] <<  8;
+    value |= data_r_4[3]      ;
+    return value;
+}
+
+// Write an arbitrary number of bytes from the given array to the sensor,
+// starting at the given register
+void VL53L0X::writeMulti(char reg, char const * src, char count)
+{
+    char data_w_n[count];
+    data_w_n[0] = reg;
+    for(int i=0; i<count; i++) {
+        data_w_n[i+1] = *(src+i);
+    }
+    i2c.write( address<<1 | 0x00, data_w_n, count, 0);
+}
+
+// Read an arbitrary number of bytes from the sensor, starting at the given
+// register, into the given array
+void VL53L0X::readMulti(char reg, char * dst, char count)
+{
+    char data_r_n[count];
+    data_r_1[0] = reg;
+    i2c.write( address<<1 | 0x00, data_r_1, 1, 0);
+    i2c.read ( address<<1 | 0x01, data_r_n, count, 0);
+    for(int i=0; i<count; i++) {
+        *(dst+i) = data_r_n[i];
+    }
+}
+
+// Set the return signal rate limit check value in units of MCPS (mega counts
+// per second). "This represents the amplitude of the signal reflected from the
+// target and detected by the device"; setting this limit presumably determines
+// the minimum measurement necessary for the sensor to report a valid reading.
+// Setting a lower limit increases the potential range of the sensor but also
+// seems to increase the likelihood of getting an inaccurate reading because of
+// unwanted reflections from objects other than the intended target.
+// Defaults to 0.25 MCPS as initialized by the ST API and this library.
+bool VL53L0X::setSignalRateLimit(float limit_Mcps)
+{
+    if (limit_Mcps < 0 || limit_Mcps > 511.99f) {
+        return false;
+    }
+
+    // Q9.7 fixed point format (9 integer bits, 7 fractional bits)
+    writeReg16Bit(FINAL_RANGE_CONFIG_MIN_COUNT_RATE_RTN_LIMIT, limit_Mcps * (1 << 7));
+    return true;
+}
+
+// Get the return signal rate limit check value in MCPS
+float VL53L0X::getSignalRateLimit(void)
+{
+    return (float)readReg16Bit(FINAL_RANGE_CONFIG_MIN_COUNT_RATE_RTN_LIMIT) / (1 << 7);
+}
+
+// Set the measurement timing budget in microseconds, which is the time allowed
+// for one measurement; the ST API and this library take care of splitting the
+// timing budget among the sub-steps in the ranging sequence. A longer timing
+// budget allows for more accurate measurements. Increasing the budget by a
+// factor of N decreases the range measurement standard deviation by a factor of
+// sqrt(N). Defaults to about 33 milliseconds; the minimum is 20 ms.
+// based on VL53L0X_set_measurement_timing_budget_micro_seconds()
+bool VL53L0X::setMeasurementTimingBudget(long budget_us)
+{
+    SequenceStepEnables enables;
+    SequenceStepTimeouts timeouts;
+
+    short const StartOverhead      = 1320; // note that this is different than the value in get_
+    short const EndOverhead        = 960;
+    short const MsrcOverhead       = 660;
+    short const TccOverhead        = 590;
+    short const DssOverhead        = 690;
+    short const PreRangeOverhead   = 660;
+    short const FinalRangeOverhead = 550;
+
+    long const MinTimingBudget = 20000;
+
+    if (budget_us < MinTimingBudget) {
+        return false;
+    }
+
+    long used_budget_us = StartOverhead + EndOverhead;
+
+    getSequenceStepEnables(&enables);
+    getSequenceStepTimeouts(&enables, &timeouts);
+
+    if (enables.tcc) {
+        used_budget_us += (timeouts.msrc_dss_tcc_us + TccOverhead);
+    }
+
+    if (enables.dss) {
+        used_budget_us += 2 * (timeouts.msrc_dss_tcc_us + DssOverhead);
+    } else if (enables.msrc) {
+        used_budget_us += (timeouts.msrc_dss_tcc_us + MsrcOverhead);
+    }
+
+    if (enables.pre_range) {
+        used_budget_us += (timeouts.pre_range_us + PreRangeOverhead);
+    }
+
+    if (enables.final_range) {
+        used_budget_us += FinalRangeOverhead;
+
+        // "Note that the final range timeout is determined by the timing
+        // budget and the sum of all other timeouts within the sequence.
+        // If there is no room for the final range timeout, then an error
+        // will be set. Otherwise the remaining time will be applied to
+        // the final range."
+
+        if (used_budget_us > budget_us) {
+            // "Requested timeout too big."
+            return false;
+        }
+
+        long final_range_timeout_us = budget_us - used_budget_us;
+
+        // set_sequence_step_timeout() begin
+        // (SequenceStepId == VL53L0X_SEQUENCESTEP_FINAL_RANGE)
+
+        // "For the final range timeout, the pre-range timeout
+        //  must be added. To do this both final and pre-range
+        //  timeouts must be expressed in macro periods MClks
+        //  because they have different vcsel periods."
+
+        short final_range_timeout_mclks =
+            timeoutMicrosecondsToMclks(final_range_timeout_us,
+                                       timeouts.final_range_vcsel_period_pclks);
+
+        if (enables.pre_range) {
+            final_range_timeout_mclks += timeouts.pre_range_mclks;
+        }
+
+        writeReg16Bit(FINAL_RANGE_CONFIG_TIMEOUT_MACROP_HI,
+                      encodeTimeout(final_range_timeout_mclks));
+
+        // set_sequence_step_timeout() end
+
+        measurement_timing_budget_us = budget_us; // store for internal reuse
+    }
+    return true;
+}
+
+// Get the measurement timing budget in microseconds
+// based on VL53L0X_get_measurement_timing_budget_micro_seconds()
+// in us
+long VL53L0X::getMeasurementTimingBudget(void)
+{
+    SequenceStepEnables enables;
+    SequenceStepTimeouts timeouts;
+
+    short const StartOverhead     = 1910; // note that this is different than the value in set_
+    short const EndOverhead        = 960;
+    short const MsrcOverhead       = 660;
+    short const TccOverhead        = 590;
+    short const DssOverhead        = 690;
+    short const PreRangeOverhead   = 660;
+    short const FinalRangeOverhead = 550;
+
+    // "Start and end overhead times always present"
+    long budget_us = StartOverhead + EndOverhead;
+
+    getSequenceStepEnables(&enables);
+    getSequenceStepTimeouts(&enables, &timeouts);
+
+    if (enables.tcc) {
+        budget_us += (timeouts.msrc_dss_tcc_us + TccOverhead);
+    }
+
+    if (enables.dss) {
+        budget_us += 2 * (timeouts.msrc_dss_tcc_us + DssOverhead);
+    } else if (enables.msrc) {
+        budget_us += (timeouts.msrc_dss_tcc_us + MsrcOverhead);
+    }
+
+    if (enables.pre_range) {
+        budget_us += (timeouts.pre_range_us + PreRangeOverhead);
+    }
+
+    if (enables.final_range) {
+        budget_us += (timeouts.final_range_us + FinalRangeOverhead);
+    }
+
+    measurement_timing_budget_us = budget_us; // store for internal reuse
+    return budget_us;
+}
+
+// Set the VCSEL (vertical cavity surface emitting laser) pulse period for the
+// given period type (pre-range or final range) to the given value in PCLKs.
+// Longer periods seem to increase the potential range of the sensor.
+// Valid values are (even numbers only):
+//  pre:  12 to 18 (initialized default: 14)
+//  final: 8 to 14 (initialized default: 10)
+// based on VL53L0X_set_vcsel_pulse_period()
+bool VL53L0X::setVcselPulsePeriod(vcselPeriodType type, char period_pclks)
+{
+    char vcsel_period_reg = encodeVcselPeriod(period_pclks);
+
+    SequenceStepEnables enables;
+    SequenceStepTimeouts timeouts;
+
+    getSequenceStepEnables(&enables);
+    getSequenceStepTimeouts(&enables, &timeouts);
+
+    // "Apply specific settings for the requested clock period"
+    // "Re-calculate and apply timeouts, in macro periods"
+
+    // "When the VCSEL period for the pre or final range is changed,
+    // the corresponding timeout must be read from the device using
+    // the current VCSEL period, then the new VCSEL period can be
+    // applied. The timeout then must be written back to the device
+    // using the new VCSEL period.
+    //
+    // For the MSRC timeout, the same applies - this timeout being
+    // dependant on the pre-range vcsel period."
+
+
+    if (type == VcselPeriodPreRange) {
+        // "Set phase check limits"
+        switch (period_pclks) {
+            case 12:
+                writeReg(PRE_RANGE_CONFIG_VALID_PHASE_HIGH, 0x18);
+                break;
+
+            case 14:
+                writeReg(PRE_RANGE_CONFIG_VALID_PHASE_HIGH, 0x30);
+                break;
+
+            case 16:
+                writeReg(PRE_RANGE_CONFIG_VALID_PHASE_HIGH, 0x40);
+                break;
+
+            case 18:
+                writeReg(PRE_RANGE_CONFIG_VALID_PHASE_HIGH, 0x50);
+                break;
+
+            default:
+                // invalid period
+                return false;
+        }
+        writeReg(PRE_RANGE_CONFIG_VALID_PHASE_LOW, 0x08);
+
+        // apply new VCSEL period
+        writeReg(PRE_RANGE_CONFIG_VCSEL_PERIOD, vcsel_period_reg);
+
+        // update timeouts
+
+        // set_sequence_step_timeout() begin
+        // (SequenceStepId == VL53L0X_SEQUENCESTEP_PRE_RANGE)
+
+        short new_pre_range_timeout_mclks =
+            timeoutMicrosecondsToMclks(timeouts.pre_range_us, period_pclks);
+
+        writeReg16Bit(PRE_RANGE_CONFIG_TIMEOUT_MACROP_HI,
+                      encodeTimeout(new_pre_range_timeout_mclks));
+
+        // set_sequence_step_timeout() end
+
+        // set_sequence_step_timeout() begin
+        // (SequenceStepId == VL53L0X_SEQUENCESTEP_MSRC)
+
+        short new_msrc_timeout_mclks =
+            timeoutMicrosecondsToMclks(timeouts.msrc_dss_tcc_us, period_pclks);
+
+        writeReg(MSRC_CONFIG_TIMEOUT_MACROP,
+                 (new_msrc_timeout_mclks > 256) ? 255 : (new_msrc_timeout_mclks - 1));
+
+        // set_sequence_step_timeout() end
+    } else if (type == VcselPeriodFinalRange) {
+        switch (period_pclks) {
+            case 8:
+                writeReg(FINAL_RANGE_CONFIG_VALID_PHASE_HIGH, 0x10);
+                writeReg(FINAL_RANGE_CONFIG_VALID_PHASE_LOW,  0x08);
+                writeReg(GLOBAL_CONFIG_VCSEL_WIDTH, 0x02);
+                writeReg(ALGO_PHASECAL_CONFIG_TIMEOUT, 0x0C);
+                writeReg(0xFF, 0x01);
+                writeReg(ALGO_PHASECAL_LIM, 0x30);
+                writeReg(0xFF, 0x00);
+                break;
+
+            case 10:
+                writeReg(FINAL_RANGE_CONFIG_VALID_PHASE_HIGH, 0x28);
+                writeReg(FINAL_RANGE_CONFIG_VALID_PHASE_LOW,  0x08);
+                writeReg(GLOBAL_CONFIG_VCSEL_WIDTH, 0x03);
+                writeReg(ALGO_PHASECAL_CONFIG_TIMEOUT, 0x09);
+                writeReg(0xFF, 0x01);
+                writeReg(ALGO_PHASECAL_LIM, 0x20);
+                writeReg(0xFF, 0x00);
+                break;
+
+            case 12:
+                writeReg(FINAL_RANGE_CONFIG_VALID_PHASE_HIGH, 0x38);
+                writeReg(FINAL_RANGE_CONFIG_VALID_PHASE_LOW,  0x08);
+                writeReg(GLOBAL_CONFIG_VCSEL_WIDTH, 0x03);
+                writeReg(ALGO_PHASECAL_CONFIG_TIMEOUT, 0x08);
+                writeReg(0xFF, 0x01);
+                writeReg(ALGO_PHASECAL_LIM, 0x20);
+                writeReg(0xFF, 0x00);
+                break;
+
+            case 14:
+                writeReg(FINAL_RANGE_CONFIG_VALID_PHASE_HIGH, 0x48);
+                writeReg(FINAL_RANGE_CONFIG_VALID_PHASE_LOW,  0x08);
+                writeReg(GLOBAL_CONFIG_VCSEL_WIDTH, 0x03);
+                writeReg(ALGO_PHASECAL_CONFIG_TIMEOUT, 0x07);
+                writeReg(0xFF, 0x01);
+                writeReg(ALGO_PHASECAL_LIM, 0x20);
+                writeReg(0xFF, 0x00);
+                break;
+
+            default:
+                // invalid period
+                return false;
+        }
+
+        // apply new VCSEL period
+        writeReg(FINAL_RANGE_CONFIG_VCSEL_PERIOD, vcsel_period_reg);
+
+        // update timeouts
+
+        // set_sequence_step_timeout() begin
+        // (SequenceStepId == VL53L0X_SEQUENCESTEP_FINAL_RANGE)
+
+        // "For the final range timeout, the pre-range timeout
+        //  must be added. To do this both final and pre-range
+        //  timeouts must be expressed in macro periods MClks
+        //  because they have different vcsel periods."
+
+        short new_final_range_timeout_mclks =
+            timeoutMicrosecondsToMclks(timeouts.final_range_us, period_pclks);
+
+        if (enables.pre_range) {
+            new_final_range_timeout_mclks += timeouts.pre_range_mclks;
+        }
+
+        writeReg16Bit(FINAL_RANGE_CONFIG_TIMEOUT_MACROP_HI,
+                      encodeTimeout(new_final_range_timeout_mclks));
+
+        // set_sequence_step_timeout end
+    } else {
+        // invalid type
+        return false;
+    }
+
+    // "Finally, the timing budget must be re-applied"
+
+    setMeasurementTimingBudget(measurement_timing_budget_us);
+
+    // "Perform the phase calibration. This is needed after changing on vcsel period."
+    // VL53L0X_perform_phase_calibration() begin
+
+    char sequence_config = readReg(SYSTEM_SEQUENCE_CONFIG);
+    writeReg(SYSTEM_SEQUENCE_CONFIG, 0x02);
+    performSingleRefCalibration(0x0);
+    writeReg(SYSTEM_SEQUENCE_CONFIG, sequence_config);
+
+    // VL53L0X_perform_phase_calibration() end
+
+    return true;
+}
+
+// Get the VCSEL pulse period in PCLKs for the given period type.
+// based on VL53L0X_get_vcsel_pulse_period()
+char VL53L0X::getVcselPulsePeriod(vcselPeriodType type)
+{
+    if (type == VcselPeriodPreRange) {
+        return decodeVcselPeriod(readReg(PRE_RANGE_CONFIG_VCSEL_PERIOD));
+    } else if (type == VcselPeriodFinalRange) {
+        return decodeVcselPeriod(readReg(FINAL_RANGE_CONFIG_VCSEL_PERIOD));
+    } else {
+        return 255;
+    }
+}
+
+// Start continuous ranging measurements. If period_ms (optional) is 0 or not
+// given, continuous back-to-back mode is used (the sensor takes measurements as
+// often as possible); otherwise, continuous timed mode is used, with the given
+// inter-measurement period in milliseconds determining how often the sensor
+// takes a measurement.
+// based on VL53L0X_StartMeasurement()
+void VL53L0X::startContinuous(long period_ms)
+{
+    writeReg(0x80, 0x01);
+    writeReg(0xFF, 0x01);
+    writeReg(0x00, 0x00);
+    writeReg(0x91, stop_variable);
+    writeReg(0x00, 0x01);
+    writeReg(0xFF, 0x00);
+    writeReg(0x80, 0x00);
+
+    if (period_ms != 0) {
+        // continuous timed mode
+
+        // VL53L0X_SetInterMeasurementPeriodMilliSeconds() begin
+
+        short osc_calibrate_val = readReg16Bit(OSC_CALIBRATE_VAL);
+
+        if (osc_calibrate_val != 0) {
+            period_ms *= osc_calibrate_val;
+        }
+
+        writeReg32Bit(SYSTEM_INTERMEASUREMENT_PERIOD, period_ms);
+
+        // VL53L0X_SetInterMeasurementPeriodMilliSeconds() end
+
+        writeReg(SYSRANGE_START, 0x04); // VL53L0X_REG_SYSRANGE_MODE_TIMED
+    } else {
+        // continuous back-to-back mode
+        writeReg(SYSRANGE_START, 0x02); // VL53L0X_REG_SYSRANGE_MODE_BACKTOBACK
+    }
+}
+
+// Stop continuous measurements
+// based on VL53L0X_StopMeasurement()
+void VL53L0X::stopContinuous(void)
+{
+    writeReg(SYSRANGE_START, 0x01); // VL53L0X_REG_SYSRANGE_MODE_SINGLESHOT
+
+    writeReg(0xFF, 0x01);
+    writeReg(0x00, 0x00);
+    writeReg(0x91, 0x00);
+    writeReg(0x00, 0x01);
+    writeReg(0xFF, 0x00);
+}
+
+// Returns a range reading in millimeters when continuous mode is active
+// (readRangeSingleMillimeters() also calls this function after starting a
+// single-shot range measurement)
+short VL53L0X::readRangeContinuousMillimeters(void)
+{
+//    startTimeout();
+//    while ((readReg(RESULT_INTERRUPT_STATUS) & 0x07) == 0) {
+//        if (checkTimeoutExpired()) {
+//            did_timeout = true;
+//            return 32767;
+//        }
+//    }
+
+    // assumptions: Linearity Corrective Gain is 1000 (default);
+    // fractional ranging is not enabled
+    short range = readReg16Bit(RESULT_RANGE_STATUS + 10);
+
+    writeReg(SYSTEM_INTERRUPT_CLEAR, 0x01);
+
+    return range;
+}
+
+// Performs a single-shot range measurement and returns the reading in
+// millimeters
+// based on VL53L0X_PerformSingleRangingMeasurement()
+short VL53L0X::readRangeSingleMillimeters(void)
+{
+    writeReg(0x80, 0x01);
+    writeReg(0xFF, 0x01);
+    writeReg(0x00, 0x00);
+    writeReg(0x91, stop_variable);
+    writeReg(0x00, 0x01);
+    writeReg(0xFF, 0x00);
+    writeReg(0x80, 0x00);
+
+    writeReg(SYSRANGE_START, 0x01);
+
+    // "Wait until start bit has been cleared"
+//    startTimeout();
+//    while (readReg(SYSRANGE_START) & 0x01) {
+//        if (checkTimeoutExpired()) {
+//            did_timeout = true;
+//            return 32767;
+//        }
+//    }
+
+    return readRangeContinuousMillimeters();
+}
+
+// Did a timeout occur in one of the read functions since the last call to
+// timeoutOccurred()?
+bool VL53L0X::timeoutOccurred()
+{
+    bool tmp = did_timeout;
+    did_timeout = false;
+    return tmp;
+}
+
+// Private Methods /////////////////////////////////////////////////////////////
+
+// Get reference SPAD (single photon avalanche diode) count and type
+// based on VL53L0X_get_info_from_device(),
+// but only gets reference SPAD count and type
+bool VL53L0X::getSpadInfo(char * count, bool * type_is_aperture)
+{
+    char tmp;
+
+    writeReg(0x80, 0x01);
+    writeReg(0xFF, 0x01);
+    writeReg(0x00, 0x00);
+
+    writeReg(0xFF, 0x06);
+    writeReg(0x83, readReg(0x83) | 0x04);
+    writeReg(0xFF, 0x07);
+    writeReg(0x81, 0x01);
+
+    writeReg(0x80, 0x01);
+
+    writeReg(0x94, 0x6b);
+    writeReg(0x83, 0x00);
+//    startTimeout();
+    wait_ms(1);
+    while (readReg(0x83) == 0x00) {
+//        if (checkTimeoutExpired()) {
+//            return false;
+//        }
+    }
+    writeReg(0x83, 0x01);
+    tmp = readReg(0x92);
+
+    *count = tmp & 0x7f;
+    *type_is_aperture = (tmp >> 7) & 0x01;
+
+    writeReg(0x81, 0x00);
+    writeReg(0xFF, 0x06);
+    writeReg(0x83, readReg( 0x83  & ~0x04));
+    writeReg(0xFF, 0x01);
+    writeReg(0x00, 0x01);
+
+    writeReg(0xFF, 0x00);
+    writeReg(0x80, 0x00);
+
+    return true;
+}
+
+// Get sequence step enables
+// based on VL53L0X_GetSequenceStepEnables()
+void VL53L0X::getSequenceStepEnables(SequenceStepEnables * enables)
+{
+    char sequence_config = readReg(SYSTEM_SEQUENCE_CONFIG);
+
+    enables->tcc          = (sequence_config >> 4) & 0x1;
+    enables->dss          = (sequence_config >> 3) & 0x1;
+    enables->msrc         = (sequence_config >> 2) & 0x1;
+    enables->pre_range    = (sequence_config >> 6) & 0x1;
+    enables->final_range  = (sequence_config >> 7) & 0x1;
+}
+
+// Get sequence step timeouts
+// based on get_sequence_step_timeout(),
+// but gets all timeouts instead of just the requested one, and also stores
+// intermediate values
+void VL53L0X::getSequenceStepTimeouts(SequenceStepEnables const * enables, SequenceStepTimeouts * timeouts)
+{
+    timeouts->pre_range_vcsel_period_pclks = getVcselPulsePeriod(VcselPeriodPreRange);
+
+    timeouts->msrc_dss_tcc_mclks = readReg(MSRC_CONFIG_TIMEOUT_MACROP) + 1;
+    timeouts->msrc_dss_tcc_us =
+        timeoutMclksToMicroseconds(timeouts->msrc_dss_tcc_mclks,
+                                   timeouts->pre_range_vcsel_period_pclks);
+
+    timeouts->pre_range_mclks =
+        decodeTimeout(readReg16Bit(PRE_RANGE_CONFIG_TIMEOUT_MACROP_HI));
+    timeouts->pre_range_us =
+        timeoutMclksToMicroseconds(timeouts->pre_range_mclks,
+                                   timeouts->pre_range_vcsel_period_pclks);
+
+    timeouts->final_range_vcsel_period_pclks = getVcselPulsePeriod(VcselPeriodFinalRange);
+
+    timeouts->final_range_mclks =
+        decodeTimeout(readReg16Bit(FINAL_RANGE_CONFIG_TIMEOUT_MACROP_HI));
+
+    if (enables->pre_range) {
+        timeouts->final_range_mclks -= timeouts->pre_range_mclks;
+    }
+
+    timeouts->final_range_us =
+        timeoutMclksToMicroseconds(timeouts->final_range_mclks,
+                                   timeouts->final_range_vcsel_period_pclks);
+}
+
+// Decode sequence step timeout in MCLKs from register value
+// based on VL53L0X_decode_timeout()
+// Note: the original function returned a long, but the return value is
+// always stored in a short.
+short VL53L0X::decodeTimeout(short reg_val)
+{
+    // format: "(LSByte * 2^MSByte) + 1"
+    return (short)((reg_val & 0x00FF) <<
+                   (short)((reg_val & 0xFF00) >> 8)) + 1;
+}
+
+// Encode sequence step timeout register value from timeout in MCLKs
+// based on VL53L0X_encode_timeout()
+// Note: the original function took a short, but the argument passed to it
+// is always a short.
+short VL53L0X::encodeTimeout(short timeout_mclks)
+{
+    // format: "(LSByte * 2^MSByte) + 1"
+
+    long ls_byte = 0;
+    short 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 MCLKs to microseconds with given VCSEL period in PCLKs
+// based on VL53L0X_calc_timeout_us()
+long VL53L0X::timeoutMclksToMicroseconds(short timeout_period_mclks, char vcsel_period_pclks)
+{
+    long macro_period_ns = calcMacroPeriod(vcsel_period_pclks);
+
+    return ((timeout_period_mclks * macro_period_ns) + (macro_period_ns / 2)) / 1000;
+}
+
+// Convert sequence step timeout from microseconds to MCLKs with given VCSEL period in PCLKs
+// based on VL53L0X_calc_timeout_mclks()
+long VL53L0X::timeoutMicrosecondsToMclks(long timeout_period_us, char vcsel_period_pclks)
+{
+    long macro_period_ns = calcMacroPeriod(vcsel_period_pclks);
+
+    return (((timeout_period_us * 1000) + (macro_period_ns / 2)) / macro_period_ns);
+}
+
+
+// based on VL53L0X_perform_single_ref_calibration()
+bool VL53L0X::performSingleRefCalibration(char vhv_init_byte)
+{
+    writeReg(SYSRANGE_START, 0x01 | vhv_init_byte); // VL53L0X_REG_SYSRANGE_MODE_START_STOP
+
+//    startTimeout();
+    wait_ms(1);
+    while ((readReg(RESULT_INTERRUPT_STATUS) & 0x07) == 0) {
+//        if (checkTimeoutExpired()) {
+//            return false;
+//        }
+    }
+
+    writeReg(SYSTEM_INTERRUPT_CLEAR, 0x01);
+
+    writeReg(SYSRANGE_START, 0x00);
+
+    return true;
+}
diff -r 000000000000 -r d738e3a03cf8 VL53L0X_SH.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/VL53L0X_SH.h	Thu Feb 16 08:45:17 2017 +0000
@@ -0,0 +1,182 @@
+#ifndef VL53L0X_SH_h
+#define VL53L0X_SH_h
+#include "mbed.h"
+
+extern  I2C         i2c;
+class   VL53L0X
+{
+public:
+    // register addresses from API vl53l0x_device.h (ordered as listed there)
+    enum regAddr {
+        SYSRANGE_START                              = 0x00,
+
+        SYSTEM_THRESH_HIGH                          = 0x0C,
+        SYSTEM_THRESH_LOW                           = 0x0E,
+
+        SYSTEM_SEQUENCE_CONFIG                      = 0x01,
+        SYSTEM_RANGE_CONFIG                         = 0x09,
+        SYSTEM_INTERMEASUREMENT_PERIOD              = 0x04,
+
+        SYSTEM_INTERRUPT_CONFIG_GPIO                = 0x0A,
+
+        GPIO_HV_MUX_ACTIVE_HIGH                     = 0x84,
+
+        SYSTEM_INTERRUPT_CLEAR                      = 0x0B,
+
+        RESULT_INTERRUPT_STATUS                     = 0x13,
+        RESULT_RANGE_STATUS                         = 0x14,
+
+        RESULT_CORE_AMBIENT_WINDOW_EVENTS_RTN       = 0xBC,
+        RESULT_CORE_RANGING_TOTAL_EVENTS_RTN        = 0xC0,
+        RESULT_CORE_AMBIENT_WINDOW_EVENTS_REF       = 0xD0,
+        RESULT_CORE_RANGING_TOTAL_EVENTS_REF        = 0xD4,
+        RESULT_PEAK_SIGNAL_RATE_REF                 = 0xB6,
+
+        ALGO_PART_TO_PART_RANGE_OFFSET_MM           = 0x28,
+
+        I2C_SLAVE_DEVICE_ADDRESS                    = 0x8A,
+
+        MSRC_CONFIG_CONTROL                         = 0x60,
+
+        PRE_RANGE_CONFIG_MIN_SNR                    = 0x27,
+        PRE_RANGE_CONFIG_VALID_PHASE_LOW            = 0x56,
+        PRE_RANGE_CONFIG_VALID_PHASE_HIGH           = 0x57,
+        PRE_RANGE_MIN_COUNT_RATE_RTN_LIMIT          = 0x64,
+
+        FINAL_RANGE_CONFIG_MIN_SNR                  = 0x67,
+        FINAL_RANGE_CONFIG_VALID_PHASE_LOW          = 0x47,
+        FINAL_RANGE_CONFIG_VALID_PHASE_HIGH         = 0x48,
+        FINAL_RANGE_CONFIG_MIN_COUNT_RATE_RTN_LIMIT = 0x44,
+
+        PRE_RANGE_CONFIG_SIGMA_THRESH_HI            = 0x61,
+        PRE_RANGE_CONFIG_SIGMA_THRESH_LO            = 0x62,
+
+        PRE_RANGE_CONFIG_VCSEL_PERIOD               = 0x50,
+        PRE_RANGE_CONFIG_TIMEOUT_MACROP_HI          = 0x51,
+        PRE_RANGE_CONFIG_TIMEOUT_MACROP_LO          = 0x52,
+
+        SYSTEM_HISTOGRAM_BIN                        = 0x81,
+        HISTOGRAM_CONFIG_INITIAL_PHASE_SELECT       = 0x33,
+        HISTOGRAM_CONFIG_READOUT_CTRL               = 0x55,
+
+        FINAL_RANGE_CONFIG_VCSEL_PERIOD             = 0x70,
+        FINAL_RANGE_CONFIG_TIMEOUT_MACROP_HI        = 0x71,
+        FINAL_RANGE_CONFIG_TIMEOUT_MACROP_LO        = 0x72,
+        CROSSTALK_COMPENSATION_PEAK_RATE_MCPS       = 0x20,
+
+        MSRC_CONFIG_TIMEOUT_MACROP                  = 0x46,
+
+        SOFT_RESET_GO2_SOFT_RESET_N                 = 0xBF,
+        IDENTIFICATION_MODEL_ID                     = 0xC0,
+        IDENTIFICATION_REVISION_ID                  = 0xC2,
+
+        OSC_CALIBRATE_VAL                           = 0xF8,
+
+        GLOBAL_CONFIG_VCSEL_WIDTH                   = 0x32,
+        GLOBAL_CONFIG_SPAD_ENABLES_REF_0            = 0xB0,
+        GLOBAL_CONFIG_SPAD_ENABLES_REF_1            = 0xB1,
+        GLOBAL_CONFIG_SPAD_ENABLES_REF_2            = 0xB2,
+        GLOBAL_CONFIG_SPAD_ENABLES_REF_3            = 0xB3,
+        GLOBAL_CONFIG_SPAD_ENABLES_REF_4            = 0xB4,
+        GLOBAL_CONFIG_SPAD_ENABLES_REF_5            = 0xB5,
+
+        GLOBAL_CONFIG_REF_EN_START_SELECT           = 0xB6,
+        DYNAMIC_SPAD_NUM_REQUESTED_REF_SPAD         = 0x4E,
+        DYNAMIC_SPAD_REF_EN_START_OFFSET            = 0x4F,
+        POWER_MANAGEMENT_GO1_POWER_FORCE            = 0x80,
+
+        VHV_CONFIG_PAD_SCL_SDA__EXTSUP_HV           = 0x89,
+
+        ALGO_PHASECAL_LIM                           = 0x30,
+        ALGO_PHASECAL_CONFIG_TIMEOUT                = 0x30,
+    };
+
+    enum vcselPeriodType { VcselPeriodPreRange, VcselPeriodFinalRange };
+
+    char last_status; // status of last I2C transmission
+
+    VL53L0X(void);
+
+    void setAddress(char new_addr);
+    inline char getAddress(void) {
+        return address;
+    }
+
+    bool init(bool io_2v8 = true);
+
+    void writeReg(char reg, char value);
+    void writeReg16Bit(char reg, short value);
+    void writeReg32Bit(char reg, long value);
+    char readReg(char reg);
+    short readReg16Bit(char reg);
+    long readReg32Bit(char reg);
+
+    void writeMulti(char reg, char const * src, char count);
+    void readMulti(char reg, char * dst, char count);
+
+    bool setSignalRateLimit(float limit_Mcps);
+    float getSignalRateLimit(void);
+
+    bool setMeasurementTimingBudget(long budget_us);
+    long getMeasurementTimingBudget(void);
+
+    bool setVcselPulsePeriod(vcselPeriodType type, char period_pclks);
+    char getVcselPulsePeriod(vcselPeriodType type);
+
+    void startContinuous(long period_ms = 0);
+    void stopContinuous(void);
+    short readRangeContinuousMillimeters(void);
+    short readRangeSingleMillimeters(void);
+
+    inline void setTimeout(short timeout) {
+        io_timeout = timeout;
+    }
+    inline short getTimeout(void) {
+        return io_timeout;
+    }
+    bool timeoutOccurred(void);
+
+private:
+    // TCC: Target CentreCheck
+    // MSRC: Minimum Signal Rate Check
+    // DSS: Dynamic Spad Selection
+
+    struct SequenceStepEnables {
+        bool tcc, msrc, dss, pre_range, final_range;
+    };
+
+    struct SequenceStepTimeouts {
+        short pre_range_vcsel_period_pclks, final_range_vcsel_period_pclks;
+
+        short msrc_dss_tcc_mclks, pre_range_mclks, final_range_mclks;
+        long msrc_dss_tcc_us,    pre_range_us,    final_range_us;
+    };
+
+    char    data_w_2[2];            //buff for write
+    char    data_w_3[3];            //buff for write
+    char    data_w_5[5];            //buff for write
+    char    data_r_1[1];            //buff for read
+    char    data_r_2[2];            //buff for read
+    char    data_r_4[4];            //buff for read
+    char    address;
+    short   io_timeout;
+    bool    did_timeout;
+    short   timeout_start_ms;
+
+    char stop_variable; // read by init and used when starting measurement; is StopVariable field of VL53L0X_DevData_t structure in API
+    long measurement_timing_budget_us;
+
+    bool getSpadInfo(char * count, bool * type_is_aperture);
+
+    void getSequenceStepEnables(SequenceStepEnables * enables);
+    void getSequenceStepTimeouts(SequenceStepEnables const * enables, SequenceStepTimeouts * timeouts);
+
+    bool performSingleRefCalibration(char vhv_init_byte);
+
+    static short decodeTimeout(short value);
+    static short encodeTimeout(short timeout_mclks);
+    static long timeoutMclksToMicroseconds(short timeout_period_mclks, char vcsel_period_pclks);
+    static long timeoutMicrosecondsToMclks(long timeout_period_us, char vcsel_period_pclks);
+};
+
+#endif
\ No newline at end of file
diff -r 000000000000 -r d738e3a03cf8 main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Feb 16 08:45:17 2017 +0000
@@ -0,0 +1,84 @@
+#include "mbed.h"
+#include "VL53L0X_SH.h"
+
+#define Rms 5000            //TT rate
+#define dt  0.005f
+#define NN  200
+
+#define constrain(amt,low,high) ((amt)<(low)?(low):((amt)>(high)?(high):(amt)))
+
+//↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓GPIO registor↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓//
+//~~~structure~~~//
+DigitalOut  led(D13);           //detection
+DigitalOut  TT_ext(D12);
+
+//~~~VL53L0X_I2C~~~//
+//I2C         i2c(D14, D15);      //I2C reg(SDA, SCL)
+VL53L0X sensor;
+//~~~Serial~~~//
+Serial      pc(D1, D0);         //Serial reg(TX RX)
+//↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑end of GPIO registor↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑//
+//↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓Varible registor↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓//
+//~~~globle~~~//
+Ticker  TT;                     //call a timer
+int     count = 0;              //one second counter for extrenal led blink
+
+//~~~VL53L0X_I2C~~~//
+int     Distance = 0;
+//↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑end of Varible registor↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑//
+//↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓Function registor↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓//
+void    init_TIMER();           //set TT_main() rate
+void    TT_main();              //timebase function rated by TT
+void    init_IO();              //initialize IO state
+float   lpf(float input, float output_old, float frequency);    //lpf discrete
+//↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑end of Function registor↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑//
+//↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓main funtion↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓//
+int main()
+{
+    init_IO();                  //initialized value
+    sensor.init();              //init SENSOR
+    sensor.setTimeout(500);
+    sensor.startContinuous();
+    NVIC_SetPriority(TIM5_IRQn, 51);    //!!!!!!!!!!!!!!!!!!!!!!!!!
+    init_TIMER();               //start TT_main
+
+    while(1) {                  //main() loop
+        if(count >= NN) {       //check if main working
+            count=0;
+            led = !led;
+        }
+    }
+
+}
+//↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑end of main funtion↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑//
+//↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓Timebase funtion↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓//
+void init_TIMER()                   //set TT_main{} rate
+{
+    TT.attach_us(&TT_main, Rms);
+}
+void TT_main()                      //interrupt function by TT
+{
+    TT_ext = !TT_ext;               //indicate TT_main() function working
+    count = count+1;                //one second counter
+    Distance = sensor.readRangeContinuousMillimeters();
+
+//for Serial-Oscilloscope
+    pc.printf("%d\r", Distance);
+}
+//↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑end of Timebase funtion↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑//
+//↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓init_IO funtion↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓//
+void init_IO(void)                  //initialize
+{
+    pc.baud(9600);            //set baud rate
+    TT_ext = 0;
+    led = 0;
+}
+//↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑end of init_IO funtion↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑//
+//↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓lpf funtion↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓//
+float lpf(float input, float output_old, float frequency)
+{
+    float output = 0;
+    output = (output_old + frequency*dt*input) / (1 + frequency*dt);
+    return output;
+}
+//↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑end of lpf funtion↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑//
\ No newline at end of file
diff -r 000000000000 -r d738e3a03cf8 mbed.bld
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Thu Feb 16 08:45:17 2017 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/176b8275d35d
\ No newline at end of file