Change SPI memory page as needed when reading/writing through SPI

In SPI mode, we must change the memory page depending on which register is
  being read/written.

Renamed const _BME680_REG_STATUS to _BME680_REG_MEAS_STATUS to more closely
  match the name in the datasheet.

Author: jraber

adafruit_bme680.py

@@ -52,11 +52,11 @@
 _BME680_REG_SOFTRESET = const(0xE0)
 _BME680_REG_CTRL_GAS = const(0x71)
 _BME680_REG_CTRL_HUM = const(0x72)
-_BME280_REG_STATUS = const(0xF3)
+_BME680_REG_STATUS = const(0x73)
 _BME680_REG_CTRL_MEAS = const(0x74)
 _BME680_REG_CONFIG = const(0x75)
 
-_BME680_REG_STATUS = const(0x1D)
+_BME680_REG_MEAS_STATUS = const(0x1D)
 _BME680_REG_PDATA = const(0x1F)
 _BME680_REG_TDATA = const(0x22)
 _BME680_REG_HDATA = const(0x25)
@@ -266,7 +266,7 @@ def _perform_reading(self):
         self._write(_BME680_REG_CTRL_MEAS, [ctrl])
         new_data = False
         while not new_data:
-            data = self._read(_BME680_REG_STATUS, 15)
+            data = self._read(_BME680_REG_MEAS_STATUS, 15)
             new_data = data[0] & 0x80 != 0
             time.sleep(0.005)
         self._last_reading = time.monotonic()
@@ -368,6 +368,11 @@ def __init__(self, spi, cs, baudrate=100000, debug=False, *, refresh_rate=10):
         super().__init__(refresh_rate=refresh_rate)
 
     def _read(self, register, length):
+        if register != _BME680_REG_STATUS:
+            #_BME680_REG_STATUS exists in both SPI memory pages
+            #For all other registers, we must set the correct memory page
+            self._set_spi_mem_page(register)
+
         register = (register | 0x80) & 0xFF  # Read single, bit 7 high.
         with self._spi as spi:
             spi.write(bytearray([register]))  #pylint: disable=no-member
@@ -378,6 +383,10 @@ def _read(self, register, length):
             return result
 
     def _write(self, register, values):
+        if register != _BME680_REG_STATUS:
+            #_BME680_REG_STATUS exists in both SPI memory pages
+            #For all other registers, we must set the correct memory page
+            self._set_spi_mem_page(register)
         register &= 0x7F  # Write, bit 7 low.
         with self._spi as spi:
             buffer = bytearray(2 * len(values))
@@ -387,3 +396,9 @@ def _write(self, register, values):
             spi.write(buffer) #pylint: disable=no-member
             if self._debug:
                 print("\t$%02X <= %s" % (values[0], [hex(i) for i in values[1:]]))
+
+    def _set_spi_mem_page(self, register):
+        spi_mem_page = 0x00
+        if register < 0x80:
+            spi_mem_page = 0x10
+        self._write(_BME680_REG_STATUS, spi_mem_page)