Micropython port

adafruit_max31865.py

@@ -23,10 +23,11 @@
 `adafruit_max31865`
 ====================================================
 
-CircuitPython module for the MAX31865 platinum RTD temperature sensor.  See
+MicroPython module for the MAX31865 platinum RTD temperature sensor.  See
 examples/simpletest.py for an example of the usage.
 
 * Author(s): Tony DiCola
+* micropython port: arofarn
 
 Implementation Notes
 --------------------
@@ -44,16 +45,15 @@ Implementation Notes
 
 **Software and Dependencies:**
 
-* Adafruit CircuitPython firmware for the ESP8622 and M0-based boards:
-  https://github.com/adafruit/circuitpython/releases
-* Adafruit's Bus Device library: https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
+* Micropython firmware :
+  https://micropython.org/download
 """
 import math
 import time
+from machine import Pin
 
 from micropython import const
 
-import adafruit_bus_device.spi_device as spi_device
 
 __version__ = "0.0.0-auto.0"
 __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_MAX31865.git"
@@ -91,21 +91,29 @@ _RTD_B = -5.775e-7
 class MAX31865:
     """Driver for the MAX31865 thermocouple amplifier."""
 
-    # Class-level buffer for reading and writing data with the sensor.
-    # This reduces memory allocations but means the code is not re-entrant or
-    # thread safe!
-    _BUFFER = bytearray(3)
-
-    def __init__(self, spi, cs, *, rtd_nominal=100, ref_resistor=430.0, wires=2):
+    def __init__(
+                self, spi, cs, *, rtd_nominal=100, ref_resistor=430.0,
+                wires=2, filter_frequency=60
+                ):
         self.rtd_nominal = rtd_nominal
         self.ref_resistor = ref_resistor
-        self._device = spi_device.SPIDevice(
-            spi, cs, baudrate=500000, polarity=0, phase=1
-        )
+        self._spi = spi
+        self._cs = cs
+        self._cs.init(mode=Pin.OUT, pull=Pin.PULL_UP)
+        self._cs.value(1)
+
+        # Set 50Hz or 60Hz filter.
+        if filter_frequency not in (50, 60):
+            raise ValueError("Filter_frequency must be a value of 50 or 60!")
+        config = self._read_u8(_MAX31865_CONFIG_REG)
+        if filter_frequency == 50:
+            config |= _MAX31865_CONFIG_FILT50HZ
+        else:
+            config &= ~_MAX31865_CONFIG_FILT50HZ
+
         # Set wire config register based on the number of wires specified.
         if wires not in (2, 3, 4):
             raise ValueError("Wires must be a value of 2, 3, or 4!")
-        config = self._read_u8(_MAX31865_CONFIG_REG)
         if wires == 3:
             config |= _MAX31865_CONFIG_3WIRE
         else:
@@ -119,26 +127,30 @@ class MAX31865:
     # pylint: disable=no-member
     def _read_u8(self, address):
         # Read an 8-bit unsigned value from the specified 8-bit address.
-        with self._device as device:
-            self._BUFFER[0] = address & 0x7F
-            device.write(self._BUFFER, end=1)
-            device.readinto(self._BUFFER, end=1)
-        return self._BUFFER[0]
+        buf=bytearray(1)
+        self._cs.value(0)
+        self._spi.write(bytes([address & 0x7F]))
+        self._spi.readinto(buf, 1)
+        self._cs.value(1)
+        return buf[0]
 
     def _read_u16(self, address):
         # Read a 16-bit BE unsigned value from the specified 8-bit address.
-        with self._device as device:
-            self._BUFFER[0] = address & 0x7F
-            device.write(self._BUFFER, end=1)
-            device.readinto(self._BUFFER, end=2)
-        return (self._BUFFER[0] << 8) | self._BUFFER[1]
+        buf=bytearray(2)
+        self._cs.value(0)
+        self._spi.write(bytes([address & 0x7F]))
+        self._spi.readinto(buf, 1)
+        self._cs.value(1)
+        return (buf[0] << 8) | buf[1]
 
     def _write_u8(self, address, val):
         # Write an 8-bit unsigned value to the specified 8-bit address.
-        with self._device as device:
-            self._BUFFER[0] = (address | 0x80) & 0xFF
-            self._BUFFER[1] = val & 0xFF
-            device.write(self._BUFFER, end=2)
+        buf=bytearray(2)
+        buf[0] = (address | 0x80) & 0xFF
+        buf[1] = val & 0xFF
+        self._cs.value(0)
+        self._spi.write(buf)
+        self._cs.value(1)
 
     # pylint: enable=no-member