Added SPI support

Author: fxsheep

README.md

@@ -9,9 +9,9 @@ https://github.com/vitally/BMP280
 https://github.com/micropython-IMU/micropython-bmp180
 
 ## Constructor
-**BMP280(i2c_bus, addr=0x76, use_case=BMP280_CASE_HANDHELD_DYN)**
-* *i2c_bus* - the I2C bus to use
-* *addr* - I2C address of the BMP280 (always the same)
+**BMP280(bus, addr_cs=0x76, use_case=BMP280_CASE_HANDHELD_DYN)**
+* *bus* - the I2C/SPI bus to use
+* *addr_cs* - when I2C is used: I2C address of the BMP280 (always the same), when SPI is used: CS pin
 * *use_case* - Use case to start the BMP280 with. Set to None to disable measuring on boot.
 
 ## Enums

bmp280.py

@@ -86,9 +86,11 @@
 
 
 class BMP280:
-    def __init__(self, i2c_bus, addr=0x76, use_case=BMP280_CASE_HANDHELD_DYN):
-        self._bmp_i2c = i2c_bus
-        self._i2c_addr = addr
+    # when 'bus' is an I2C object, 'addr_cs' is I2C address
+    # when 'bus' is an SPI object, 'addr_cs' is Pin object of the CS pin
+    def __init__(self, bus, addr_cs=0x76, use_case=BMP280_CASE_HANDHELD_DYN):
+        self._bmp_bus = bus
+        self._addr_cs = addr_cs
 
         # read calibration data
         # < little-endian
@@ -123,12 +125,25 @@ def __init__(self, i2c_bus, addr=0x76, use_case=BMP280_CASE_HANDHELD_DYN):
             self.use_case(use_case)
 
     def _read(self, addr, size=1):
-        return self._bmp_i2c.readfrom_mem(self._i2c_addr, addr, size)
+        if hasattr(self._bmp_bus, 'readfrom_mem'):
+            return self._bmp_bus.readfrom_mem(self._addr_cs, addr, size)
+        else:
+            self._addr_cs(0)
+            self._bmp_bus.write(bytearray([addr]))
+            dat = self._bmp_bus.read(size)
+            self._addr_cs(1)
+            return dat
 
     def _write(self, addr, b_arr):
         if not type(b_arr) is bytearray:
             b_arr = bytearray([b_arr])
-        return self._bmp_i2c.writeto_mem(self._i2c_addr, addr, b_arr)
+        if hasattr(self._bmp_bus, 'writeto_mem'):
+            return self._bmp_bus.writeto_mem(self._addr_cs, addr, b_arr)
+        else:
+            self._addr_cs(0)
+            ret = self._bmp_bus.write(bytearray([addr & 0x7f]) + b_arr)
+            self._addr_cs(1)
+            return ret
 
     def _gauge(self):
         # TODO limit new reads