ltalexan
Posts: 1
Joined: Mon Oct 15, 2018 6:15 pm

Getting Started with Raspberry Pi PID Temperature Controller

Mon Oct 15, 2018 6:47 pm

Salutations Raspberry Pi Forum Browsers!

I am a senior undergraduate student in chemical engineering. For my senior design project, I have been tasked with building an automated temperature controller for a kamado-style smoker, like the Big Green Egg. After researching the subject extensively, most similar projects I have found online have been seemingly complicated from a hardware standpoint (at least for someone who has little background in electronics). For example, this project (https://github.com/CapnBry/HeaterMeter/wiki) includes tons of resistors, capacitors, etc. For the project, I would need ways of connecting type K thermocouples (at least 2) to a Raspberry Pi, and a way to connect a variable speed blower (controlled by pulse width modulation) to a Raspberry Pi. Is all of the complex circuitry in the project above necessary for this?

From my understanding, I should be able to execute the above functions with a thermocouple amplifier breakout board such as the MAX31855 and somehow modifying some of the GPIO pins for pulse width modulation to control a variable speed blower. Is this correct? Any pointers or explanations I can get would be helpful.

Thanks!

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Gavinmc42
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Joined: Wed Aug 28, 2013 3:31 am

Re: Getting Started with Raspberry Pi PID Temperature Controller

Tue Oct 16, 2018 1:19 am

It is not really that hard. (unless you really want to do it in Linux).
Temperature sensors and heater/blower controlled by solidstate relays.

I do this for Real time Polymerase Chain Reactors (DNA replicator) , did not even need PID software.
PWM not needed either as thermal time delays are quite long ie 100ms, even 500ms+.

Started with Python on Linux, but the OS got in the way of my i2c temp sensor reading.
So now I use baremetal on Pi with Ultibo.

All that other stuff is nice but mostly frosting on the cake.
Sensor/relay and some simple software, start there and get that working first.

Once that is working then you can add data logging and screenshots of temperature plots etc
https://ultibo.org/forum/viewtopic.php? ... screenshot

Or even webpage plotting
https://ultibo.org/forum/viewtopic.php? ... tting#p373
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reted30
Posts: 13
Joined: Mon Apr 30, 2018 7:24 am

Re: Getting Started with Raspberry Pi PID Temperature Controller

Mon Oct 29, 2018 10:03 am

For K type thermocouple I have been using the ADS1115 I2C module.

But for controlling Pwm, use FET driver MIC5021

and will be easily connected with raspberry pi using I2C interface.

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DougieLawson
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Re: Getting Started with Raspberry Pi PID Temperature Controller

Mon Oct 29, 2018 10:22 am

reted30 wrote:
Mon Oct 29, 2018 10:03 am
For K type thermocouple I have been using the ADS1115 I2C module.
A dedicated MAX31855K is a better amplifier for a K-type thermocouple.
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