Robot Projects > Rolling

Double_ing up the "Time of Flight" sensors

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Gareth:


Two is better than one...... (or 4 or 8 etcetcetc).

Following successful experiments with 1 single Time of Flight distance sensor mounted to Stepper, watching the scan process its seems to lend its self to setting the scan to just 180° and mount two sensors back to back to extract the whole 360°...... (or 90° scan with 4 sensors, hope you see where I am going with this :-)

Generally I2C devices come with a fixed address, so doubling up the same I2C animals with the same I2C address is not possible...... unless Slave address's are implemented.

The VL53LOX sensor has a trick up its sleeve ... the "XSHUT" pin   (aka... reset pin!).

#include <Wire.h>
#include <VL53L0X.h>

#define XSHUT1 4
#define XSHUT2 5

#define TOF1_I2Caddress 41
#define TOF2_I2Caddress 42

VL53L0X TOF1;
VL53L0X TOF2;

void setup()
{
  Serial.begin(115200);
  Wire.begin(21,23);
  pinMode(XSHUT1, OUTPUT);  pinMode(XSHUT2, OUTPUT);

// the magic part happens here .....
  TOF1.setAddress(TOF1_I2Caddress); pinMode(XSHUT1, INPUT); delay(10);
  TOF2.setAddress(TOF2_I2Caddress); pinMode(XSHUT2, INPUT); delay(10);
 
  TOF1.init(); TOF1.startContinuous(); 
  TOF2.init(); TOF2.startContinuous();
}

void loop()
{
  Serial.print(TOF1.readRangeContinuousMillimeters());
  Serial.print(':');
  Serial.println(TOF2.readRangeContinuousMillimeters());
}

During runtime it is possible to slip any address you wish to each individual sensor.

The TOF comes with a default I2C address of 00101001BIN

The above code is generic so if you have multiple TOF's then the code is easily expanded.....

If you are just using 2 TOF's the simplified code can be used below due to one TOF defaulting to address 41 :-

#include <Wire.h>
#include <VL53L0X.h>

#define XSHUT2 5

// no need to program I2C address of TOF1 as it defaults to 41 anyways \ö/
#define TOF2_I2Caddress 42

VL53L0X TOF1;
VL53L0X TOF2;

void setup()
{
  Serial.begin(115200);
  Wire.begin(21,23);
  pinMode(XSHUT2, OUTPUT);
 
  TOF2.setAddress(TOF2_I2Caddress); pinMode(XSHUT2, INPUT); delay(10);
 
  TOF1.init(); TOF1.startContinuous(); 
  TOF2.init(); TOF2.startContinuous();
}
void loop()
{
  Serial.print(TOF1.readRangeContinuousMillimeters());
  Serial.print(':');
  Serial.println(TOF2.readRangeContinuousMillimeters());
}


My stepper has a hollow spindle shaft... 5 wires will pass easily through... a 360° rotation would screw the wires up... a 180° rotation would only half screw the wires up... however a 90° rotation would be even better... (i.e. eliminating need for WiFi/BlueTooth OTA data transfer ...FlyByWire becomes an interesting solution again).

maelh:
Nice! I also got a couple of theses sensors a couple weeks ago. I have yet to solder the pins on and use them.
To create a point cloud I think a Intel Realsense would be better.

Curious to see where you go with this!

P.S.: You could use a slip ring instead of a wireless connection.

Gareth:

--- Quote from: maelh on November 11, 2018, 05:22:23 AM ---P.S.: You could use a slip ring instead of a wireless connection.

--- End quote ---
ermmm 100% no  :P
As this project started with the idea of Cost effective LIDAR  (with my aversion to having a slipped disk)......
evolution went so :-
LIDAR with Hollow shaft Stepper     Workio
LIDAR with WIFI Mesh                    Workio slow unstable                   (trashed)
LIDAR with Bluetooth                     Workio Slow solid                        (trashed)
LIDAR 360° Wired Ping-pong style  Workio Fast however twisty wires   (trashed)
LIDAR*2 180° Wired Ping-pong      Workio Fast                                 (Current)

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