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).

GroG

6 years 2 months ago

Brilliant Gareth ! .. its evolving into a new sensor organ ... 
At this point you just need a steper controller & i2c host + 2/4/8/... eyes

what is your stepper degree ? Are you planning to 1/2 step ?  I imagine the sampling rate of the sensor is extremely fast, so that sub-degree measurements could be easily made ?

I am not 100% on speed yet.... though a single sample acquisition takes (of pdf spec) 35ms

The stepper is a 200 step ... and yes I have wired the microstepping to logic pins ...so step angle can be changed on the fly via software (workio)

Scan strategy is not yet clear.... indeed I had thought of allowing a first scan at high speed (effectively 200 steps over 360°) and then go into micro-stepping when it finds a region of interest.

It all hangs on how much memory I can cram all the scanned data into... time will tell.