fixes for cpython & pi: hard reset before i2c init, tighten struct.unpack()

adafruit_si4713.py

@@ -120,11 +120,24 @@ class SI4713:
 
     def __init__(self, i2c, *, address=_SI4710_ADDR1, reset=None, timeout_s=0.1):
         self._timeout_s = timeout_s
-        self._device = i2c_device.I2CDevice(i2c, address)
+
         # Configure reset line if it was provided.
         self._reset = reset
+
         if self._reset is not None:
             self._reset.switch_to_output(value=True)
+
+            # Toggle reset line low to reset the chip and then wait a bit for
+            # startup - this is necessary before initializing as an i2c device
+            # on at least the Raspberry Pi, and potentially elsewhere:
+            self._reset.value = True
+            time.sleep(0.01)
+            self._reset.value = False
+            time.sleep(0.01)
+            self._reset.value = True
+            time.sleep(0.25)
+
+        self._device = i2c_device.I2CDevice(i2c, address)
         self.reset()
         # Check product ID.
         if self._get_product_number() != 13:
@@ -382,8 +395,7 @@ def input_level(self):
         """
         # Perform ASQ request, then parse out 8 bit _signed_ input level value.
         self._asq_status()
-        return struct.unpack('bbbbb', self._BUFFER)[4]
-
+        return struct.unpack('bbbbb', self._BUFFER[0:5])[4]
     @property
     def audio_signal_status(self):
         """Retrieve the ASQ or audio signal quality status value from the chip.

docs/examples.rst

@@ -3,6 +3,6 @@ Simple test
 
 Ensure your device works with this simple test.
 
-.. literalinclude:: ../examples/simpletest.py
-    :caption: examples/simpletest.py
+.. literalinclude:: ../examples/si4713_simpletest.py
+    :caption: examples/si4713_simpletest.py
     :linenos:

examples/simpletest.py → examples/si4713_simpletest.py

@@ -4,27 +4,31 @@
 
 import board
 import busio
+import digitalio
 
 import adafruit_si4713
 
-
 # Specify the FM frequency to transmit on in kilohertz.  As the datasheet
 # mentions you can only specify 50khz steps!
 FREQUENCY_KHZ = 102300  # 102.300mhz
 
-
 # Initialize I2C bus.
 i2c = busio.I2C(board.SCL, board.SDA)
 
 # Initialize SI4713.
-si4713 = adafruit_si4713.SI4713(i2c)
+# si4713 = adafruit_si4713.SI4713(i2c)
+
 # Alternatively you can specify the I2C address of the device if it changed:
-#si4713 = adafruit_si4713.SI4713(i2c, address=0x11)
-# Also if you hooked up the reset line you can specify that too.  Make sure
-# to pass in a DigitalInOut instance:
-#import digitalio
-#reset = digitalio.DigitalInOut(board.D5)
-#si4713 = adafruit_si4713.SI4713(i2c, reset=reset)
+# si4713 = adafruit_si4713.SI4713(i2c, address=0x11)
+
+# If you hooked up the reset line you should specify that too.  Make sure
+# to pass in a DigitalInOut instance.  You will need the reset pin with the
+# Raspberry Pi, and probably other devices:
+reset = digitalio.DigitalInOut(board.D5)
+
+print('initializing si4713 instance')
+si4713 = adafruit_si4713.SI4713(i2c, reset=reset, timeout_s=0.5)
+print('done')
 
 # Measure the noise level for the transmit frequency (this assumes automatic
 # antenna capacitance setting, but see below to adjust to a specific value).