Adding a virtual Frame temperature sensor

Developers
1

Hi @all,

I´m working on a Python script that reads out four DS18B20 sensors, which are mounted in the four vertikal aluminium extrusions on the corners to get a arithmetic mean for the frame temperature.

I´ve added a additional MCU temperature sensor to klipper like this:

[temperature_sensor frame]
sensor_type: temperature_host
sensor_path: /home/pi/frame

If i change the value in the “frame” file, klipper shows me the right temperature. But if I run the script, klipper don´t refresh the value.

Here is my script:

#!/usr/bin/env python
#coding=utf-8
import os, time, sys

os.system('modprobe w1-gpio')
os.system('modprobe w1-therm')

file_path = 'frame'
sys.stdout = open(file_path, "w")

sensorcount = 4
sensors = ['28-0621b2312f10', '28-0120426e687f', '28-0621b245c0cf', '28-0120428c8a85'];
temp_sum = 0;
sensorpath = '/sys/bus/w1/devices/'
sensorfile = '/w1_slave'

def callsensor(sensor):
  f = open(sensorpath + sensor + sensorfile, 'r')
  lines = f.readlines()
  f.close()
  if lines[0].strip() [-3:] != 'YES':
    sys.exit('Fehler bei Sensor ' + sensor)

  temp_line = lines[1].find('t=')				
  if temp_line != -1:						
    temp_output = lines[1].strip() [temp_line+2:]
    t= in temp_output schreiben
    return temp_output

for i in range(0, sensorcount):
  s = sensors[i]    						
  temp_sum = temp_sum + int(callsensor(s))

temp_arr = int(temp_sum/sensorcount)
print(temp_arr)
sys.exit()

It´s working well, but klipper doesn´t update the temp value.
I think it´s caused by the truncation before the write of the file from python.

I know that i can implement the four sensors in klipper directly, but not the arithmetic mean. I just want one value for the frame, so i can wait for the frame to get on temperature before the print starts.

Can someone help me with this problem?

2

I´ve found a working solution. The script now only updates the file if the value changes by 0.1 degrees.

#!/usr/bin/env python3
#coding=utf-8
import os, time, sys						#Bibliotheken laden

os.system('modprobe w1-gpio')					#Kernelmodule laden
os.system('modprobe w1-therm')

file_path = 'frame'						#Ausgabedatei festlegen
#sys.stdout = open(file_path, "w")				#Standardausgabe in Datei umleiten

sensorcount = 4							#Festlegen, wieviele Sensoren vorhanden sind
sensors = ['28-0621b2312f10', '28-0120426e687f', '28-0621b245c0cf', '28-0120428c8a85'];	#Array mit den Sensor-IDs
temp_sum = 0;
temp_arr_old = 0;
sensorpath = '/sys/bus/w1/devices/'				#Pfad zum Sensorverzeichnis
sensorfile = '/w1_slave'					#Geraetedatei

def callsensor(sensor):
  f = open(sensorpath + sensor + sensorfile, 'r')		#Pfad, Sensor-ID und Geraetedatei zusammensetzen, Datei im Lesemodus oeffnen
  lines = f.readlines()						#Inhalt der Datei in lines schreiben
  f.close()							#Datei schliessen
  if lines[0].strip() [-3:] != 'YES':				#Index 0 (Zeile 1) strippen und pruefen, ob die letzten 3 Buchstaben YES sind
    sys.exit('Fehler bei Sensor ' + sensor)			#Wenn nein: Abbruch mit Sensornummer als Argument
  temp_line = lines[1].find('t=')				#Den Index (Position) von t= in temp_line schreiben
  if temp_line != -1:						#Wenn nicht -1 (=String nicht gefunden)
    temp_output = lines[1].strip() [temp_line+2:]		#Index 1 (Zeile 2) strippen und die Zeichen nach t= in temp_output schreiben
    return temp_output						#Funktion beenden und temp_celsius ausgeben

while True:
  temp_sum = 0
  for i in range(0, sensorcount):					#for-Schleife von 0 bis 3
    s = sensors[i]    						#Sensor-ID 0-3 auf s schreiben
    temp_sum = temp_sum + int(callsensor(s))

  temp_arr = int(temp_sum/sensorcount)
  if int(temp_arr/100) != int(temp_arr_old/100):
   with open(file_path, "w+") as external_file:
      temp_arr_old = temp_arr
      print(str(temp_arr), file=external_file, end='')
      external_file.close()
sys.exit()							#Programm beenden

Next step is to set the script as a service, so it starts on bootup

3

Out of curiosity how big are the temperature differences between the four extrusions?

4

It’s up to 10 degree. Depending on the airflow of the chamber heater.

5

Now the script is working very well. I´ve added as a service, so it starts automaticly when the pi boots up.

But after a while, klipper doesn´t refresh the temperature. After a reboot of klipper it´s working again.

@koconnor Is there a failsafe mode in klipper?

6

I have added a temperature_combined sensor class you can use

1 Like
7

@emjay276 Thank you very much for your work. I´ll try it immediately

1 Like
8

I noticed the ‘temperature_combined’ feature popup this weekend and tried it out on my Voron 0
This turns the processor fan in the back of the machine when either of the processors get hot.
Works well thanks.

#####################################################################
#      Temperature Sensors
#####################################################################
[temperature_sensor SKR_Pico]
sensor_type: temperature_mcu

[temperature_sensor Raspberry_Pi]
sensor_type: temperature_host

#####################################################################
# Processor Fan Control
#####################################################################
[temperature_fan processors_maximum]
pin: gpio20                                                       # the fan control pin (must be a mosfet or a pwm fan)
control: watermark                                                # the type of hysteresis we are using
max_delta: 3.0                                                    # fan turns on/off at 3° over/under target_temp
sensor_type: temperature_combined                                 # new temperature type
sensor_list: temperature_sensor SKR_Pico, temperature_sensor Raspberry_Pi
combination_method: max                                           # use the maximum reading of the sensors
maximum_deviation: 999.9                                          # we don't care about the difference in temperature
max_temp: 85                                                      # just the valid temperature ranges
min_temp: 0
target_temp: 57.0                                                 # the initial target temperature for the fan
max_speed: 1.0
min_speed: 0.3
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