From a74e1b573b943914e384074f37b6df18b275a1f5 Mon Sep 17 00:00:00 2001
From: jens <jens.ahrensfeld@gmx.de>
Date: Sun, 13 Dec 2020 19:18:50 +0100
Subject: [PATCH] - added max31865

---
 components/sensor/tempSensor_max31865.py | 122 +++++++++++++++++++++++
 components/sensor/tempsensor_factory.py  |   3 +
 2 files changed, 125 insertions(+)
 create mode 100755 components/sensor/tempSensor_max31865.py

diff --git a/components/sensor/tempSensor_max31865.py b/components/sensor/tempSensor_max31865.py
new file mode 100755
index 0000000..046aaf2
--- /dev/null
+++ b/components/sensor/tempSensor_max31865.py
@@ -0,0 +1,122 @@
+#!/usr/bin/python3
+import time
+import spidev
+from atemperatureSensor import ATemperatureSensor
+
+
+class TempSensor_max31865(ATemperatureSensor):
+	def name(self):
+		return "Max31865"
+
+	def __init__(self):
+		# Open SPI bus
+		self.spi = spidev.SpiDev()
+		self.spi.open(0, 0)
+		self.spi.max_speed_hz = 50000
+		self.spi.mode = 0b01
+		self.temp_correction = -0.2
+		self.write_reg(0x00, 0xA3)
+		time.sleep(0.100)
+		self.digits = 0
+		self.log("Created")
+		self.temp = self.temperature()
+
+	def read_reg(self, addr):
+		reg = self.spi.xfer([addr, 0xFF])
+
+		return reg[1]
+
+	def write_reg(self, addr, data):
+		self.spi.xfer([addr+0x80, data])
+
+	def read_digits(self):
+		msb = self.read_reg(0x01)
+		lsb = self.read_reg(0x02)
+		if lsb & 0x01 == 0x00:
+			self.digits = float(256*msb + lsb)/2
+
+		self.write_reg(0x00, 0xA3)
+		return self.digits
+
+	def temperature(self):
+		return self.__tempRaw()
+
+	def __tempRaw(self):
+		try:
+			digits = self.read_digits()
+		except: 
+			return None
+		R = TempSensor_max31865.calc_R(430, digits)
+		T = TempSensor_max31865.vanDusen_temp(R) + self.temp_correction
+#		print("R={:.3f} Ohm, T={:.2f} degC".format(R, T))
+		return T
+
+	@staticmethod
+	def calc_R(Rref, digits):
+		k = digits / 8192 / 4
+		R = k*Rref
+
+		return R
+
+	@staticmethod
+	def vanDusenLut (R0, Tmin, Tmax, dT):
+		a = +3.90830e-03
+		b = -5.77500e-07
+		c = -4.18301e-12
+
+		Rv = []
+		Tv = []
+		T = Tmin
+		while T <= Tmax:
+			R = R0*(1 + a*T + b*T**2)
+
+			if T < 0.0:
+				R += R0*c*(T - 100)*T**3
+
+			Rv.append(R)
+			Tv.append(T)
+			T += dT
+
+		return Rv, Tv
+
+	@staticmethod
+	def vanDusen_temp(Rmeas):
+		RLut, TLut = TempSensor_max31865.vanDusenLut(100, -150, +500, 1.0)
+
+		# Find candidate
+		i = 0
+		for R in RLut:
+			if R > Rmeas:
+				break
+			i += 1
+
+		# Linear interpolation
+		R0 = RLut[i-1]
+		R1 = RLut[i]
+		T0 = TLut[i-1]
+		T1 = TLut[i]
+
+		dR = R1 - R0
+		dT = T1 - T0
+
+		k = (Rmeas-R0)/dR
+		T = T0 + dT*k
+
+		return T
+
+	def process(self):
+		temp = self.temperature()
+		self.temp = temp
+
+# Main
+if __name__ == '__main__':
+
+
+	TempSensor_max31865 = TempSensor_max31865()
+	for i in range (0, 8):
+		print("Reg[0x{}]: 0x{:02X}".format(i, TempSensor_max31865.read_reg(i)))
+
+	print(TempSensor_max31865.temperature())
+
+	print("End of program")
+
diff --git a/components/sensor/tempsensor_factory.py b/components/sensor/tempsensor_factory.py
index 115dd3b..533d1bd 100644
--- a/components/sensor/tempsensor_factory.py
+++ b/components/sensor/tempsensor_factory.py
@@ -1,4 +1,5 @@
 from components.sensor.tempSensorSim import TempSensorSim
+from components.sensor.tempSensor_max31865 import TempSensor_max31865
 
 
 class TempSensorFactory:
@@ -6,3 +7,5 @@ class TempSensorFactory:
 	def create(name):
 		if "sim" in name:
 			return TempSensorSim()
+		elif "31865" in name:
+			return TempSensor_max31865()