SKR mini E3 V3.0 Third Thermistor Sensor

[markxyx]

Hi, is there any pin that I can use for third thermistor sensor for heated chamber? I tried Z stop and PS-on. No luck.

[radek8]

Theoretically, it would be possible. You need to find a free pin that supports analog input (voltage measurement), connect a resistor divider with a capacitor and define a pin in the pin set. If you can do it, try it. But if you ask like this, you better buy a board that has 3 connectors for measuring temperature ....

[markxyx]

So damn hard...seem like using pi's pin would be much easier.

[radek8]

Measuring temperature is not the same as connecting a limit switch. Temperature measurement is performed by measuring the voltage on a resistive divider that contains a thermistor. You also can't connect a fan to a random pin. The fan must switch Mosfet.

[radek8]

Caution the processor has 3.3V logic and some pins are sensitive to higher voltages and can be destroyed by 5V voltages!

[Jaybeam]

I don't know if you stil need this but I use pin PA5 for my chamber thermistor:

• On a E3 V2 this is the pin labeled SCK on the SPI1 header.
• On a E3 V2 this is the pin labeled CLK on the SPI1 header.

[ironhalik]

Oh man @Jaybeam - coming back back with an answer half a year later is going above and beyond. Thank you. I'm going to try it.

[Dataro81]

There is a CLK on SP1 header for the SKR E3 V3, but not SCK. Additionally, how do you determine what the pin definition is?

@ironhalik any luck?

[Dataro81]

Is this where the definition is? The diagram is confusing.

[Dataro81]

nm, just found out that sck and clk are different acronyms for the same thing. SCK stands for Spi ClocK. CLK stands for spi CLocK.

So I am assuming i just need to connect to GND and CLK (PA5)? Do I still need to add a resistor divider with a capacitor?

[Dataro81]

I don't know if you stil need this but I use pin PA5 for my chamber thermistor:

• On a E3 V2 this is the pin labeled SCK on the SPI1 header.
• On a E3 V2 this is the pin labeled CLK on the SPI1 header.

For the second line, i think you meant to write E3 V3, right?

[NonaSuomy]

For the E3 V3.0 you can connect a 3rd thermistor to MOSI on the SPI1 8 Pin Header. I tested this with the Umbilical board for a Voron 0.1. It does cause issues with the SD Card but it's not too much of problem with Klipper you can just disable it then update firmware etc.

For Klipper

#####################################################################
#   Chamber Temperature Sensor
#####################################################################

[temperature_sensor Chamber_Temp]
sensor_type: Generic 3950
sensor_pin: PA7 # PA7 is MOSI on the SPI header. Has an onboard 10K pullup to 3v3. Connect the other leg of the thermistor to ground
pullup_resistor: 10000

[ironhalik]

And here's for E3 v2.0 :)

[temperature_sensor chamber]
sensor_type: Generic 3950
sensor_pin: PA5
min_temp: 0
max_temp: 90
gcode_id: chamber_temp
pullup_resistor: 10200

[Dataro81]

For the E3 V3.0 you can connect a 3rd thermistor to MOSI on the SPI1 8 Pin Header. I tested this with the Umbilical board for a Voron 0.1. It does cause issues with the SD Card but it's not too much of problem with Klipper you can just disable it then update firmware etc.

For Klipper

#####################################################################
#   Chamber Temperature Sensor
#####################################################################

[temperature_sensor Chamber_Temp]
sensor_type: Generic 3950
sensor_pin: PA7 # PA7 is MOSI on the SPI header. Has an onboard 10K pullup to 3v3. Connect the other leg of the thermistor to ground
pullup_resistor: 10000

Thanks! Lol, im doing this with my voron 0.1 too! What issues does this cause with the sd card?

off-topic, I see you are using a btt 5" pitft screen. Where are you planning to mount that on the 0.1?

[NonaSuomy]

SDCard Just doesn't work as it interferes with the signal but you can just unplug the wire if you need it for a moment and plug it back in. Or just leave the SDCard out if everything is good on your printer its not really needed.

I just finished the mount for the LCD it clips on to that cross member of the tophat :D

[Dataro81]

Nice! How are you wiring it to the pi though? Not seeing the wire.

[NonaSuomy]

Goes under the front cross member at the top between the plex panel and the front cross member, down the inside front cross member to the right horizontal cross member, down the right vert member, behind the back panel into the electronics chamber to the RPi.

[ViperWorx]

Sorry to bump an old post but in a pinch you can also use pin PA1 on the Z probe header on the v2 board, I was hunting around as I have a screen that uses the CLK pin and found Klipper accepted that pin, won't be dead on accurate as it bounces around a little bit like I said, in a pinch. You also need a stupid pull up to get it reading roughly correct. Seems to work though.

Klipper config:

[temperature_sensor chamber]
sensor_type: Generic 3950
sensor_pin: PA1
pullup_resistor: 7250000

::Edit:: Also I have just found this it's for Marlin, but give the pins. Basically, if you move your Y endstop to E0 Stop (PC15) you can use the Y Stop pin (PC1) with a 10000 pullup which is a lot more stable.

Kilpper Config:

[temperature_sensor chamber]
sensor_type: Generic 3950
sensor_pin: PC1
pullup_resistor: 10000

[zeljkomarinkovic]

Sorry to bump an old post!

@Dataro81 @NonaSuomy Did you guys get stable reading from thermistor?

I have btt skr 3 mini v3 and I want to add third thermistor (ATC Semitec 104GT-2/104NT-4-R025H42G) to it. In my case i got huge fluctuations in temperature (±10 °C) like in picture.

This is from my printer.cfg

[temperature_sensor Chamber_Temp] sensor_type: ATC Semitec 104GT-2 sensor_pin: PA7 # PA7 is MOSI on the SPI header. Has an onboard 10K pullup to 3v3. Connect the other leg of the thermistor to ground min_temp: 0 max_temp: 90 gcode_id: chamber_temp pullup_resistor: 10000

Have anybody else managed to get it working?