Add timeouts to bus devices.

adafruit_bus_device/i2c_device.py

@@ -24,6 +24,7 @@
 `adafruit_bus_device.i2c_device` - I2C Bus Device
 ====================================================
 """
+import time
 
 __version__ = "0.0.0-auto.0"
 __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_BusDevice.git"
@@ -59,12 +60,14 @@ class I2CDevice:
                 device.write(bytes_read)
     """
 
-    def __init__(self, i2c, device_address, probe=True):
+    def __init__(self, i2c, device_address, probe=True, timeout=0.25):
 
         self.i2c = i2c
         self._has_write_read = hasattr(self.i2c, "writeto_then_readfrom")
         self.device_address = device_address
 
+        self.timeout = timeout
+
         if probe:
             self.__probe_for_device()
 
@@ -164,8 +167,15 @@ def write_then_readinto(
     # pylint: enable-msg=too-many-arguments
 
     def __enter__(self):
-        while not self.i2c.try_lock():
-            pass
+
+        if self.timeout is not None:
+            lock_start_time = time.monotonic()
+            while not self.i2c.try_lock():
+                if self.timeout > (time.monotonic() - lock_start_time):
+                    raise Exception("'I2CDevice' lock timed out")
+        else:
+            while not self.i2c.try_lock():
+                pass
         return self
 
     def __exit__(self, exc_type, exc_val, exc_tb):

adafruit_bus_device/spi_device.py

@@ -25,6 +25,7 @@
 `adafruit_bus_device.spi_device` - SPI Bus Device
 ====================================================
 """
+import time
 
 __version__ = "0.0.0-auto.0"
 __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_BusDevice.git"
@@ -75,20 +76,28 @@ def __init__(
         baudrate=100000,
         polarity=0,
         phase=0,
-        extra_clocks=0
+        extra_clocks=0,
+        timeout=0.25
     ):
         self.spi = spi
         self.baudrate = baudrate
         self.polarity = polarity
         self.phase = phase
         self.extra_clocks = extra_clocks
         self.chip_select = chip_select
+        self.timeout = timeout
         if self.chip_select:
             self.chip_select.switch_to_output(value=True)
 
     def __enter__(self):
-        while not self.spi.try_lock():
-            pass
+        if self.timeout is not None:
+            lock_start_time = time.monotonic()
+            while not self.spi.try_lock():
+                if self.timeout > (time.monotonic() - lock_start_time):
+                    raise Exception("'SPIDevice' lock timed out")
+        else:
+            while not self.spi.try_lock():
+                pass
         self.spi.configure(
             baudrate=self.baudrate, polarity=self.polarity, phase=self.phase
         )