HeaterMeter Variant


 
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Prather

New member
First, Bryan, thank you, thank you, thank you for creating the HeaterMeter! Your work is amazing!!!

I have a few questions:

1. I was thinking, wouldn't it be nice if the HM could control 2 smokers, 2 sous vide machines, or 1 of each?! I was looking at the schematic for 4.3 and see pin 13 isn't being used. Could i just duplicate the same blower circuitry that is connected to pin 5 and connect it to pin 13? Of course, it would need additional code/UI elements to associate the temp probe to a blower. I have the UI in my head to configure which probe is controlling a blower. This leads me to question 2...

2. I've been looking at the Netduinos that run .NET Micro. I am a C#/Java/AngularJS developer and haven't touched C++ since many years ago in college which makes the Netduinos appealing to me; I prefer not to code in C++. Also, they have a model with builtin wifi. So, couldn't I just create a Netduino project and connect the pins to a HM board in place of the ATmega and Pi? Sorry, I am not an electronics engineer but I can read instructions. haha

3. Just curious, why didn't you use an actual Arduino instead of the Pi? Could the Arduino not act as a web server and control the PID process?

Thanks again for all your time and hard work for the smoking community!
 
It's been asked here before about controlling 2 pits with a single HM and I think the answer is that there's too much going on with the code already and that it's probably best to just build 2 HMs.

As for the HM and RasPi, the RasPi provides not only just the wifi/IP stack, but it also does the initial programming of the ATMEGA chip, takes care of the graphing, emails and alerting and the rest of the config system. The RasPi doesn't do any of the PID control. That's all handled by the ATMEGA328P chip (the same chip on the Arduino Uno and others).

I don't doubt that a lot of the that functionality could be moved over to something like an ESP32, as I'm in the thick of my own little project using an ESP8266 that is performing double duty of microcontroller and web interface. There are even combined systems like the LinkIt Smart 7688 Duo that have both an ATMEGA32U4 microcontroller and a ARM CPU that you can run OpenWRT on.

That said, I think we're well into the "it's not broken, so don't fix it till it is" stage of the heatermeter.
 
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Yeah the amount of UI complexity that comes with adding a whole second set of HeaterMeter data and configuration makes it a non-starter. There are also hardware concerns, seeing as you can't just use any pin to do any functionality you desire (the blower runs hardware PWM at 62.5kHz which pin 13 can not do). It would just be a giant monstrosity everywhere you look. The cost of HeaterMeter components is fairly low, $59.33 in quantity 1, so the hundreds of hours of development time to try to get it to working would never be justified by the few users that would use it.

I'm not sure what configuration you're talking about with #2, like take a Netduino and just hook the serial lines to a HeaterMeter? That's definitely doable because the HeaterMeter is its own thing which can run the grill all on its own without a host system. As Steve said, an ESP8266 is a dirt cheap way to add a wifi frontend to a HeaterMeter (although with a Zero W only being $10, that's not a huge investment for a full system). If you do roll your own host, you'd have to duplicate the data storage for the graph somehow though.

#3 The original HeaterMeter uses an actual Arduino Uno, which was their top of the line flagship in 2009. The wifi module alone was like $75 and was garbage in that it could only serve one request at a time and even then only in like 400 bytes at a time chunks, the pages themselves had to be stored on a separate EEPROM chip because there's only 32KB of storage on the Arduino for code and data (HeaterMeter is a svelte ~24KB currently). The Arduino alone only has 2KB of RAM so there's no way to really run a webserver on it with any amount of responsiveness for even a single user. There needs to be some sort of more powerful host board.
 
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