Grill temp sensor/probe


#1

Hello, I’m trying to get a Weber meat temp probe to work with Cayenne with a mcp3008 and a Raspberry pi Zero W. I am having problems getting the probe resistance readings scaled with resistors. I believe it’s a NTC thermistor? the resistance goes up as the probe gets colder. Any thoughts or is this even possible? Thanks


#2

You can do it, but you will have to take measurements at known temperatures and come up with a formula to calculate the temp based on the reading.


#3

Ok great. I’m using a Maverick PR-003 probe and a ADS1115. The probe reads 0.474 M ohms at 39.4 degrees F, 0.150 M ohms at 88 degrees F, and 0.195 M ohms at 76.0 degrees F, With a multimeter. Connected to the ADS 1115 and the RaspberryPi Zero w connected to Cayenne the probe reads 0.7900 at 76 degrees F, and 0.7600 at 39 degrees F. Does the formula go in the Cayenne app or RaspberryPi or does it figure out the resistor size needed? Thanks


#4

This will turn out to be a bit more involved that just adding the ADS1115 through the dashboard. To get this to work correctly you will have to use the MQTT API You can see an example here of using the MQTT API with a python script on the Pi here Basically just replae the bits where I read the DHT sensors with your code to read the ADS1115, then convert it to a temp and upload to Cayenne. Let me know if you have any questions, I have this sensor and can test your code.


#5

Looks like it would be much more difficult than I thought. Currently looking for an Arduino code example to read the Maverick probe an I’m having a hard time finding one that works. Thanks


#6

Do you know what type of thermocouple the probe is (ex. type k)? I googled it but was unable to find anything useful…

Edit:
Found this, not sure how useful/accurate it is but worth a shot.


#7

The link is the correct probe. However code unfortunately drives me crazy. That’s why I love Cayenne so much with the drag and drop sensors it makes it very easy.


#8

You can use MCP9600 thermocouple with a Raspberry Pi I2C shield.
MCP9600 will give to temperature output, so you dont have to worry about the extra calculations.
Something like this MCP9600 K type thermocouple


#9

Personally I’d dump the Maverick PR-003 too and go with another thermcopuple that is type k.


#10

Hello, will the MCP9600 K type thermocouple device work directly with Cayenne? If so is it possible to convert the celsius to fahrenheit like the other devices on the Cayenne Dashboard?

Thanks


#11

It’s not supported by the Pi Agent, but again you can use the MQTT API I mentioned in your other post.