pt100.py

#!/usr/bin/env python3

from adafruit_blinka.microcontroller.bcm283x import pin
import board
import busio
import digitalio
import adafruit_max31865
from os.path import join, exists
from collections import namedtuple

PT100Result = namedtuple("PT100Result", ("sensor_name", "is_valid", "temp"))

import math
import time
import sys


class PT100:
	def __init__(self, port, ch, wires=4):
		self.wires = wires
		self.port = port
		self.ch = ch
		self.cs_pin = self.chip_select_pin(port,ch)
		if not self.cs_pin:
			sys.exit()
		# port 0 parameters
		clk = 11
		mosi = 10
		miso = 9
		if port == 1:
			clk = 21
			mosi = 20
			miso = 19
			
		self.clk = clk
		self.mosi = mosi
		self.miso = miso
		
		self.spi = busio.SPI(self.clk,MOSI=self.mosi, MISO=self.miso)
		self.cs = digitalio.DigitalInOut(self.cs_pin)
		self.sensor = adafruit_max31865.MAX31865(self.spi, self.cs, wires=self.wires)


	def read(self):
		if self.sensor:
			return PT100Result(self.get_sensor_name(), True, self.sensor.temperature)
		
	def get_sensor_type_name(self):
		return "PT100"
		
	def get_sensor_name(self):
		return "PT100_spi-%i_ch-%i" % (self.port, self.ch)

	def get_sensor_fields(self):
		return ["temp"]
		
	def chip_select_pin(self,port, ch):
		cs_pin = None
		if   port > 1:
			print("port "+str(port)+" not valid")
		elif port == 0:
			if   ch == 0:
				cs_pin = board.D4
			elif ch == 1:
				cs_pin = board.D18
			else:
				print("channel "+str(ch)+" not valid")
		else:
			if   ch == 0:
				cs_pin = board.D12
			elif ch == 1:
				cs_pin = board.D13
			elif ch == 2:
				cs_pin = board.D16
			else:
				print("channel "+str(ch)+" not valid")
			
		return cs_pin


if __name__ == "__main__":
	import argparse
	
	parser = argparse.ArgumentParser()

	parser.add_argument('--wires', type = int, default = 4)
	parser.add_argument('--port', type = int, default = 0)
	parser.add_argument('--channel', type = int, default = 0)
	args = parser.parse_args()
	
	wires = args.wires
	port = args.port
	ch = args.channel
		
	mydevice = PT100(port,ch,wires)
	

	result = mydevice.read()
	print("%s - is_valid:%r temperature:%.2f" % (result.sensor_name,result.is_valid, result.temp))