我正在使用以下代码在我的树莓上同时获得PT100（3线）和PT1000（2线）的温度。 根据{{3}}我的布线是正确的。
from Max31865 import Max31865
maxGarraum = Max31865()
maxGarraum.initPt100_3WireSensor(26, True)
maxFleisch = Max31865()
maxFleisch.initPt1000_2WireSensor(24, True)
while True:
maxGarraum.getCurrentTemp()
time.sleep(1)
我的Max31865.py如下所示：
import time, math
import RPi.GPIO as GPIO
# import numpy
class Max31865():
def initPt1000_2WireSensor(self, iCsPin):
self.csPin = iCsPin
# Fleischsensor Pt1000 (2-wire)
self.registerCode = 0xA2
self.setupGPIO()
def initPt100_3WireSensor(self, iCsPin):
self.csPin = iCsPin
# Garraumsensor Pt100 (3-wire)
self.registerCode = 0xB2
self.setupGPIO()
def setupGPIO(self):
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BOARD)
GPIO.setup(self.csPin, GPIO.OUT)
GPIO.setup(self.misoPin, GPIO.IN)
GPIO.setup(self.mosiPin, GPIO.OUT)
GPIO.setup(self.clkPin, GPIO.OUT)
GPIO.output(self.csPin, GPIO.HIGH)
GPIO.output(self.clkPin, GPIO.LOW)
GPIO.output(self.mosiPin, GPIO.LOW)
def getCurrentTemp(self):is
# b10000000 = 0x80
# 0x8x to specify 'write register value'
# 0xx0 to specify 'configuration register'
#
# 0b10110010 = 0xB2
# Config Register - https://datasheets.maximintegrated.com/en/ds/MAX31865.pdf
# ---------------
# bit 7: Vbias -> 1 (ON)
# bit 6: Conversion Mode -> 0 (MANUAL)
# bit 5: 1-shot ->1 (ON)
# bit 4: 3-wire select -> 1 (3 wire config) (0 for 2-/4-wire)
# bit 3-2: fault detection cycle -> 0 (none)
# bit 1: fault status clear -> 1 (clear any fault)
# bit 0: 50/60 Hz filter select -> 0 (60Hz)
#
# 0b11010010 or 0xD2 for continuous auto conversion
# at 60Hz (faster conversion)
# one shot
self.writeRegister(0, self.registerCode)
# conversion time is less than 100ms
time.sleep(.1) # give it 100ms for conversion
# read all registers
out = self.readRegisters(0, 8)
conf_reg = out[0]
#print("Config register byte: %x" % conf_reg)
[rtd_msb, rtd_lsb] = [out[1], out[2]]
rtd_ADC_Code = ((rtd_msb << 8) | rtd_lsb) >> 1
temp = self.calcTemperature(rtd_ADC_Code)
"""
# High fault threshold
[hft_msb, hft_lsb] = [out[3], out[4]]
hft = ((hft_msb << 8) | hft_lsb) >> 1
# Low fault threshold
[lft_msb, lft_lsb] = [out[5], out[6]]
lft = ((lft_msb << 8) | lft_lsb) >> 1
print ("High fault threshold: ", hft , " --- Low fault threshold: " , lft)
"""
status = out[7]
# 10 Mohm resistor is on breakout board to help
# detect cable faults
# bit 7: RTD High Threshold / cable fault open
# bit 6: RTD Low Threshold / cable fault short
# bit 5: REFIN- > 0.85 x VBias -> must be requested
# bit 4: REFIN- < 0.85 x VBias (FORCE- open) -> must be requested
# bit 3: RTDIN- < 0.85 x VBias (FORCE- open) -> must be requested
# bit 2: Overvoltage / undervoltage fault
# bits 1,0 don't care
# print "Status byte: %x" % status
if ((status & 0x80) == 1):
raise FaultError("High threshold limit (Cable fault/open)")
if ((status & 0x40) == 1):
raise FaultError("Low threshold limit (Cable fault/short)")
if ((status & 0x04) == 1):
raise FaultError("Overvoltage or Undervoltage Error")
return temp
def writeRegister(self, regNum, dataByte):
GPIO.output(self.csPin, GPIO.LOW)
# 0x8x to specify 'write register value'
addressByte = 0x80 | regNum;
# first byte is address byte
#print("Cs-Pin: ", self.csPin, "Addresse: ", addressByte)
self.sendByte(addressByte)
# the rest are data bytes
self.sendByte(dataByte)
GPIO.output(self.csPin, GPIO.HIGH)
def readRegisters(self, regNumStart, numRegisters):
out = []
GPIO.output(self.csPin, GPIO.LOW)
# 0x to specify 'read register value'
self.sendByte(regNumStart)
for byte in range(numRegisters):
data = self.recvByte()
out.append(data)
GPIO.output(self.csPin, GPIO.HIGH)
return out
def sendByte(self, byte):
for bit in range(8):
GPIO.output(self.clkPin, GPIO.HIGH)
if (byte & 0x80):
GPIO.output(self.mosiPin, GPIO.HIGH)
else:
GPIO.output(self.mosiPin, GPIO.LOW)
byte <<= 1
GPIO.output(self.clkPin, GPIO.LOW)
def recvByte(self):
byte = 0x00
for bit in range(8):
GPIO.output(self.clkPin, GPIO.HIGH)
byte <<= 1
if GPIO.input(self.misoPin):
byte |= 0x1
GPIO.output(self.clkPin, GPIO.LOW)
return byte
def calcTemperature(self, RTD_ADC_Code):
global temp
R_REF = 0.0 # Reference Resistor
Res0 = 0.0; # Resistance at 0 degC for 400ohm R_Ref
a = 0.0
b = 0.0
c = 0.0
if (self.registerCode == 0xA2):
############# PT1000 #############
R_REF = 4300.0 # Reference Resistor
Res0 = 1000.0; # Resistance at 0 degC for 430ohm R_Ref
a = .00381
b = -.000000602
# c = -4.18301e-12 # for -200 <= T <= 0 (degC)
c = -0.000000000006
# c = 0 # for 0 <= T <= 850 (degC)
else:
############# PT100 #############
R_REF = 430.0 # Reference Resistor
Res0 = 100.0; # Resistance at 0 degC for 430ohm R_Ref
a = .00390830
b = -.000000577500
# c = -4.18301e-12 # for -200 <= T <= 0 (degC)
c = -0.00000000000418301
# c = 0 # for 0 <= T <= 850 (degC)
Res_RTD = (RTD_ADC_Code * R_REF) / 32768.0 # PT1000 Resistance
#print("CS-Pin: " , self.csPin, " --- ADC-Value: ", RTD_ADC_Code , " --- Resistance: ", round(Res_RTD, 2) , " Ohms")
# Callendar-Van Dusen equation
# Res_RTD = Res0 * (1 + a*T + b*T**2 + c*(T-100)*T**3)
# Res_RTD = Res0 + a*Res0*T + b*Res0*T**2 # c = 0
# (c*Res0)T**4 - (c*Res0)*100*T**3
# + (b*Res0)*T**2 + (a*Res0)*T + (Res0 - Res_RTD) = 0
#
# quadratic formula:
# for 0 <= T <= 850 (degC)
temp = -(a * Res0) + math.sqrt(a * a * Res0 * Res0 - 4 * (b * Res0) * (Res0 - Res_RTD))
temp = round(temp / (2 * (b * Res0)), 2)
# removing numpy.roots will greatly speed things up
# temp_C_numpy = numpy.roots([c*Res0, -c*Res0*100, b*Res0, a*Res0, (Res0 - Res_RTD)])
# temp_C_numpy = abs(temp_C_numpy[-1])
# print "Solving Full Callendar-Van Dusen using numpy: %f" % temp_C_numpy
if (temp < 0): # use straight line approximation if less than 0
# Can also use python lib numpy to solve cubic
# Should never get here in this application
temp = (RTD_ADC_Code / 32) - 256
print ("CSPin " , self.csPin, " - ADC: ", RTD_ADC_Code , " - Resistance: ", round(Res_RTD, 2) , " Ohms - Temp: " , temp)
return temp
##############################################################################################################################
# Programmstart #
###############################################################################################################################
csPin = 0
misoPin = 21
mosiPin = 19
clkPin = 23
registerCode = 0
# BOARD:21,19,23
# BCM: 9,10,11
class FaultError(Exception):
pass
问题是我没有获得PT100-rtd的数据 - 仅适用于PT1000。 我的覆盆子布线必须正确，因为我也调整了我的代码来测试两个PT1000-rtd的接线，它可以工作。
我认为我的问题出在“getCurrentTemp（self）”。也许在readRegister（..）和writeRegister（..）中加上“regNum”和“regNumStart”。
有什么想法吗？