mirror of
https://github.com/DCC-EX/CommandStation-EX.git
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250 lines
9.5 KiB
C++
250 lines
9.5 KiB
C++
/*
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* © 2021, Neil McKechnie. All rights reserved.
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*
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* This file is part of DCC++EX API
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*
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* This is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* It is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with CommandStation. If not, see <https://www.gnu.org/licenses/>.
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*/
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/*
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* The VL53L0X Time-Of-Flight sensor operates by sending a short laser pulse and detecting
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* the reflection of the pulse. The time between the pulse and the receipt of reflections
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* is measured and used to determine the distance to the reflecting object.
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*
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* For economy of memory and processing time, this driver includes only part of the code
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* that ST provide in their API. Also, the API code isn't very clear and it is not easy
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* to identify what operations are useful and what are not.
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* The operation shown here doesn't include any calibration, so is probably not as accurate
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* as using the full driver, but it's probably accurate enough for the purpose.
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*
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* The device driver allocates up to 3 vpins to the device. A digital read on any of the pins
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* will return a value that indicates whether the object is within the threshold range (1)
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* or not (0). An analogue read on the first pin returns the last measured distance (in mm),
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* the second pin returns the signal strength, and the third pin returns detected
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* ambient light level.
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*
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* The VL53L0X is initially set to respond to I2C address 0x29. If you only have one module,
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* you can use this address. However, the address can be modified by software. If
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* you select another address, that address will be written to the device and used until the device is reset.
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*
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* If you have more than one module, then you will need to specify a digital VPIN (Arduino
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* digital output or I/O extender pin) which you connect to the module's XSHUT pin. Now,
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* when the device driver starts, the XSHUT pin is set LOW to turn the module off. Once
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* all VL53L0X modules are turned off, the driver works through each module in turn by
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* setting XSHUT to HIGH to turn the module on,, then writing the module's desired I2C address.
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* In this way, many VL53L0X modules can be connected to the one I2C bus, each one
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* using with a distinct I2C address.
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*
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* The driver is configured as follows:
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*
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* Single VL53L0X module:
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* VL53L0X::create(firstVpin, nPins, i2cAddress, lowThreshold, highThreshold);
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* Where firstVpin is the first vpin reserved for reading the device,
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* nPins is 1, 2 or 3,
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* i2cAddress is the address of the device (normally 0x29),
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* lowThreshold is the distance at which the digital vpin state is set to 1 (in mm),
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* and highThreshold is the distance at which the digital vpin state is set to 0 (in mm).
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*
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* Multiple VL53L0X modules:
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* VL53L0X::create(firstVpin, nPins, i2cAddress, lowThreshold, highThreshold, xshutPin);
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* ...
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* Where firstVpin is the first vpin reserved for reading the device,
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* nPins is 1, 2 or 3,
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* i2cAddress is the address of the device (any valid address except 0x29),
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* lowThreshold is the distance at which the digital vpin state is set to 1 (in mm),
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* highThreshold is the distance at which the digital vpin state is set to 0 (in mm),
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* and xshutPin is the VPIN number corresponding to a digital output that is connected to the
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* XSHUT terminal on the module.
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*
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* Example:
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* In mySetup function within mySetup.cpp:
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* VL53L0X::create(4000, 3, 0x29, 200, 250);
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* Sensor::create(4000, 4000, 0); // Create a sensor
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*
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* When an object comes within 200mm of the sensor, a message
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* <Q 4000>
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* will be sent over the serial USB, and when the object moves more than 250mm from the sensor,
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* a message
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* <q 4000>
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* will be sent.
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*
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*/
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#ifndef IO_VL53L0X_h
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#define IO_VL53L0X_h
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#include "IODevice.h"
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class VL53L0X : public IODevice {
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private:
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uint8_t _i2cAddress;
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uint16_t _ambient;
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uint16_t _distance;
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uint16_t _signal;
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uint16_t _onThreshold;
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uint16_t _offThreshold;
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VPIN _xshutPin;
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bool _value;
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bool _initialising = true;
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uint8_t _entryCount = 0;
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unsigned long _lastEntryTime = 0;
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bool _scanInProgress = false;
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// Register addresses
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enum : uint8_t {
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VL53L0X_REG_SYSRANGE_START=0x00,
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VL53L0X_REG_RESULT_INTERRUPT_STATUS=0x13,
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VL53L0X_REG_RESULT_RANGE_STATUS=0x14,
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VL53L0X_CONFIG_PAD_SCL_SDA__EXTSUP_HV=0x89,
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VL53L0X_REG_I2C_SLAVE_DEVICE_ADDRESS=0x8A,
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};
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const uint8_t VL53L0X_I2C_DEFAULT_ADDRESS=0x29;
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public:
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VL53L0X(VPIN firstVpin, int nPins, uint8_t i2cAddress, uint16_t onThreshold, uint16_t offThreshold, VPIN xshutPin = VPIN_NONE) {
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_firstVpin = firstVpin;
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_nPins = min(nPins, 3);
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_i2cAddress = i2cAddress;
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_onThreshold = onThreshold;
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_offThreshold = offThreshold;
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_xshutPin = xshutPin;
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_value = 0;
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addDevice(this);
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}
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static void create(VPIN firstVpin, int nPins, uint8_t i2cAddress, uint16_t onThreshold, uint16_t offThreshold, VPIN xshutPin = VPIN_NONE) {
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new VL53L0X(firstVpin, nPins, i2cAddress, onThreshold, offThreshold, xshutPin);
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}
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protected:
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void _begin() override {
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_initialising = true;
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// Check if device is already responding on the nominated address.
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if (I2CManager.exists(_i2cAddress)) {
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// Yes, it's already on this address, so skip the address initialisation.
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_entryCount = 3;
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} else {
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_entryCount = 0;
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}
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}
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void _loop(unsigned long currentMicros) override {
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if (_initialising) {
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switch (_entryCount++) {
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case 0:
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// On first entry to loop, reset this module by pulling XSHUT low. All modules
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// will be reset in turn.
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if (_xshutPin != VPIN_NONE) IODevice::write(_xshutPin, 0);
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break;
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case 1:
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// On second entry, set XSHUT pin high to allow the module to restart.
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// On the module, there is a diode in series with the XSHUT pin to
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// protect the low-voltage pin against +5V.
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if (_xshutPin != VPIN_NONE) IODevice::write(_xshutPin, 1);
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// Allow the module time to restart
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delay(10);
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// Then write the desired I2C address to the device, while this is the only
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// module responding to the default address.
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I2CManager.write(VL53L0X_I2C_DEFAULT_ADDRESS, 2, VL53L0X_REG_I2C_SLAVE_DEVICE_ADDRESS, _i2cAddress);
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break;
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case 3:
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if (I2CManager.exists(_i2cAddress)) {
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_display();
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// Set 2.8V mode
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write_reg(VL53L0X_CONFIG_PAD_SCL_SDA__EXTSUP_HV,
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read_reg(VL53L0X_CONFIG_PAD_SCL_SDA__EXTSUP_HV) | 0x01);
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}
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_initialising = false;
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_entryCount = 0;
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break;
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default:
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break;
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}
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} else if (_lastEntryTime - currentMicros > 10000UL) {
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// Service device every 10ms
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_lastEntryTime = currentMicros;
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if (!_scanInProgress) {
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// Not scanning, so initiate a scan
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write_reg(VL53L0X_REG_SYSRANGE_START, 0x01);
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_scanInProgress = true;
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} else {
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// Scan in progress, so check for completion.
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uint8_t status = read_reg(VL53L0X_REG_RESULT_RANGE_STATUS);
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if (status & 1) {
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// Completed. Retrieve data
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uint8_t inBuffer[12];
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read_registers(VL53L0X_REG_RESULT_RANGE_STATUS, inBuffer, 12);
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uint8_t deviceRangeStatus = ((inBuffer[0] & 0x78) >> 3);
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if (deviceRangeStatus == 0x0b) {
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// Range status OK, so use data
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_ambient = makeuint16(inBuffer[7], inBuffer[6]);
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_signal = makeuint16(inBuffer[9], inBuffer[8]);
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_distance = makeuint16(inBuffer[11], inBuffer[10]);
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if (_distance <= _onThreshold)
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_value = true;
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else if (_distance > _offThreshold)
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_value = false;
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}
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_scanInProgress = false;
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}
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}
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}
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}
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// For analogue read, first pin returns distance, second pin is signal strength, and third is ambient level.
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int _readAnalogue(VPIN vpin) override {
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int pin = vpin - _firstVpin;
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switch (pin) {
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case 0:
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return _distance;
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case 1:
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return _signal;
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case 2:
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return _ambient;
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default:
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return -1;
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}
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}
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// For digital read, return the same value for all pins.
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int _read(VPIN) override {
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return _value;
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}
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void _display() override {
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DIAG(F("VL53L0X I2C:x%x Configured on Vpins:%d-%d On:%dmm Off:%dmm"),
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_i2cAddress, _firstVpin, _firstVpin+_nPins-1, _onThreshold, _offThreshold);
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}
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private:
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inline uint16_t makeuint16(byte lsb, byte msb) {
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return (((uint16_t)msb) << 8) | lsb;
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}
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void write_reg(uint8_t reg, uint8_t data) {
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// write byte to register
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uint8_t outBuffer[2];
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outBuffer[0] = reg;
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outBuffer[1] = data;
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I2CManager.write(_i2cAddress, outBuffer, 2);
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}
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uint8_t read_reg(uint8_t reg) {
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// read byte from register register
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uint8_t inBuffer[1];
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I2CManager.read(_i2cAddress, inBuffer, 1, ®, 1);
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return inBuffer[0];
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}
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void read_registers(uint8_t reg, uint8_t buffer[], uint8_t size) {
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I2CManager.read(_i2cAddress, buffer, size, ®, 1);
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}
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};
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#endif // IO_VL53L0X_h
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