Merge pull request #12 from 2bndy5/master

added ability to use multiple VL53L0X on the same I2C bus

Author: jepler

adafruit_vl53l0x.py

@@ -453,3 +453,20 @@ def range(self):
         range_mm = self._read_u16(_RESULT_RANGE_STATUS + 10)
         self._write_u8(_SYSTEM_INTERRUPT_CLEAR, 0x01)
         return range_mm
+
+    def set_address(self, new_address):
+        """Set a new I2C address to the instantaited object. This is only called when using
+        multiple VL53L0X sensors on the same I2C bus (SDA & SCL pins). See also the
+        `example <examples.html#multiple-vl53l0x-on-same-i2c-bus>`_ for proper usage.
+
+        :param int new_address: The 7-bit `int` that is to be assigned to the VL53L0X sensor.
+            The address that is assigned should NOT be already in use by another device on the
+            I2C bus.
+
+        .. important:: To properly set the address to an individual VL53L0X sensor, you must
+            first ensure that all other VL53L0X sensors (using the default address of ``0x29``)
+            on the same I2C bus are in their off state by pulling the "SHDN" pins LOW. When the
+            "SHDN" pin is pulled HIGH again the default I2C address is ``0x29``.
+        """
+        self._write_u8(_I2C_SLAVE_DEVICE_ADDRESS, new_address & 0x7f)
+        self._device.device_address = new_address

docs/examples.rst

@@ -6,3 +6,12 @@ Ensure your device works with this simple test.
 .. literalinclude:: ../examples/vl53l0x_simpletest.py
     :caption: examples/vl53l0x_simpletest.py
     :linenos:
+
+Multiple VL53L0X on Same I2C Bus
+--------------------------------
+
+Copy "../examples/vl53l0x_multiple_sensors.py" to your "CIRCUITPY" drive, then run the script with ``from vl53l0x_multiple_sensors import *``
+
+.. literalinclude:: ../examples/vl53l0x_multiple_sensors.py
+    :caption: examples/vl53l0x_multiple_sensors.py
+    :linenos:

examples/vl53l0x_multiple_sensors.py

@@ -0,0 +1,64 @@
+"""
+Example of how to use the adafruit_vl53l0x library to change the assigned address of
+multiple VL53L0X sensors on the same I2C bus. This example only focuses on 2 VL53L0X
+sensors, but can be modified for more. BE AWARE: a multitude of sensors may require
+more current than the on-board 3V regulator can output (typical current consumption during
+active range readings is about 19 mA per sensor).
+"""
+import time
+import board
+from digitalio import DigitalInOut
+from adafruit_vl53l0x import VL53L0X
+
+# declare the singleton variable for the default I2C bus
+i2c = board.I2C()
+
+# declare the digital output pins connected to the "SHDN" pin on each VL53L0X sensor
+xshut = [
+    DigitalInOut(board.D7),
+    DigitalInOut(board.D9),
+    # add more VL53L0X sensors by defining their SHDN pins here
+    ]
+
+for power_pin in xshut:
+    # make sure these pins are a digital output, not a digital input
+    power_pin.switch_to_output(value=False)
+    # These pins are active when Low, meaning:
+    #   if the output signal is LOW, then the VL53L0X sensor is off.
+    #   if the output signal is HIGH, then the VL53L0X sensor is on.
+# all VL53L0X sensors are now off
+
+# initialize a list to be used for the array of VL53L0X sensors
+vl53 = []
+
+# now change the addresses of the VL53L0X sensors
+for i, power_pin in enumerate(xshut):
+    # turn on the VL53L0X to allow hardware check
+    power_pin.value = True
+    # instantiate the VL53L0X sensor on the I2C bus & insert it into the "vl53" list
+    vl53.insert(i, VL53L0X(i2c)) # also performs VL53L0X hardware check
+    # no need to change the address of the last VL53L0X sensor
+    if i < len(xshut) - 1:
+        # default address is 0x29. Change that to something else
+        vl53[i].set_address(i + 0x30) # address assigned should NOT be already in use
+# there is a helpful list of pre-designated I2C addresses for various I2C devices at
+# https://learn.adafruit.com/i2c-addresses/the-list
+# According to this list 0x30-0x34 are available, although the list may be incomplete.
+# In the python REPR, you can scan for all I2C devices that are attached and detirmine
+# their addresses using:
+#   >>> import board
+#   >>> i2c = board.I2C()
+#   >>> if i2c.try_lock():
+#   >>>     [hex(x) for x in i2c.scan()]
+#   >>>     i2c.unlock()
+
+def detect_range(count=5):
+    """ take count=5 samples """
+    while count:
+        for index, sensor in enumerate(vl53):
+            print('Sensor {} Range: {}mm'.format(index + 1, sensor.range))
+        time.sleep(1.0)
+        count -= 1
+
+print("Multiple VL53L0X sensors' addresses are assigned properly\n"
+      "execute detect_range() to read each sensors range readings")