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Adafruit_MicroPython_MAX31685
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Fix SPI device baudrate, polarity, phase usage.

This commit is contained in:
Tony DiCola 2017-12-06 18:13:48 -08:00
parent 36888f86a1
commit 48f0a3b5f2
1 changed files with 7 additions and 9 deletions
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16
adafruit_max31865.py
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@ -72,7 +72,8 @@ class MAX31865:
def __init__(self, spi, cs, rtd_nominal=100, ref_resistor=430.0, wires=2):
self.rtd_nominal = rtd_nominal
self.ref_resistor = ref_resistor
self._device = spi_device.SPIDevice(spi, cs)
self._device = spi_device.SPIDevice(spi, cs, baudrate=500000,
polarity=0, phase=1)
# 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!')
@ -90,7 +91,6 @@ class MAX31865:
def _read_u8(self, address):
# Read an 8-bit unsigned value from the specified 8-bit address.
with self._device as device:
device.configure(baudrate=500000, phase=1, polarity=0)
self._BUFFER[0] = address & 0x7F
device.write(self._BUFFER, end=1)
device.readinto(self._BUFFER, end=1)
@ -99,7 +99,6 @@ class MAX31865:
def _read_u16(self, address):
# Read a 16-bit BE unsigned value from the specified 8-bit address.
with self._device as device:
device.configure(baudrate=500000, phase=1, polarity=0)
self._BUFFER[0] = address & 0x7F
device.write(self._BUFFER, end=1)
device.readinto(self._BUFFER, end=2)
@ -108,8 +107,7 @@ class MAX31865:
def _write_u8(self, address, val):
# Write an 8-bit unsigned value to the specified 8-bit address.
with self._device as device:
device.configure(baudrate=500000, phase=1, polarity=0)
self._BUFFER[0] = (address & 0xFF) | 0x80
self._BUFFER[0] = (address | 0x80) & 0xFF
self._BUFFER[1] = val & 0xFF
device.write(self._BUFFER, end=2)
@ -195,13 +193,13 @@ class MAX31865:
Celsius.
"""
Rt = self.read_rtd()
Rt //= 32768
Rt /= 32768
Rt *= self.ref_resistor
Z1 = -_RTD_A
Z2 = _RTD_A * _RTD_A - (4 * _RTD_B);
Z3 = (4 * _RTD_B) / self.rtd_nominal;
Z2 = _RTD_A * _RTD_A - (4 * _RTD_B)
Z3 = (4 * _RTD_B) / self.rtd_nominal
Z4 = 2 * _RTD_B
temp = Z2 + (Z3 * Rt);
temp = Z2 + (Z3 * Rt)
temp = (math.sqrt(temp) + Z1) / Z4
if temp >= 0:
return temp