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By TechMo
#200163
Hey Guys
Good to be part of this forum

I have seen some Instructables on how to use the Arduino as a Thermostat. Basically a LCD is connected with some Push Buttons to set the High and Low Temp thresholds and a Probe does the measuring.

My question is if I have 5 appliances for example and I want to measure and control the temperature of each appliance separately, would I need to have 5 separate Adruino boards or can I connect 5 X Probes + 5 X LCD's + 5 X whatever else is required to 1 single Arduino Board and the program the arduino to control each appliance temperature separately?

Thanks
Mo
By Valen
#200174
Are the appliances (sensor location and heating actuator) located close to one another or are they physically far apart?
What temperature probes?
Which LCD?

5x LCD to one Arduino (microcontroller)? Why multiple? Can't you operate all from one spot?

p.s. It's your job to define the "5x whatever else". Not ours.
By TechMo
#200181
Hi Valen

Thanks for your response. Let me elaborate further

I have 3 X Gas Fryers (The ones used to make Fries) and 2 Gas Grillers (Flat Top Model). All 5 items are lined up next to each other - perhaps a 2 Meter stretch from the first item to the last.
The purpose of having 5 individual LCD Screens is to monitor the temperature of each appliance individually.
I'm not sure what temp probes will be compatible - I'll have to research that further.

As for other peripherals, I'm thinking maybe 2 push buttons with each appliance to increase or decrease the temperature.

I'm open to any suggestions - this is what my limited imagination could think of - I'm sure there exists a better solution - the basic idea is to control the temperature of gas appliances individually.

Thanks
Mo
By Valen
#200182
I guess it depends on how many pins each LCD screen requires to interface. And how the temperature probes are measured, meaning by the Arduino itself (analog pins) or each probe has a dedicated measurement converter with digital output. And how many pins are required for that to work. If they work with an I2C bus then they can easily be managed by a single Arduino board through 2 pins. Serial display interfaces would take a single TX pin per display and maybe a common RX pin if they can respond. If however the LCDs have an 11-pin interface then pin count becomes an issue. Some pins may be common and used as a bus or through multiplex chips. But still, 5 times X pins add up quickly. And then there are still the as of yet unknown gas valve actuators. That could mean the difference between 5 (pro)micros/nanos or 1 Mega.

As for processing load, thermostat control in and of itself isn't so demanding. Read or analog convert 5 temperatures, maybe do some PID calculations and switch on the valves as needed. It depends more on how fancy you want to show the data on the LCD. Will they be simple lcd or should it have a (color) graphical display. The latter will require more processing to get the data across.

Since the fryers and grillers are co-located within 2 meter I don't see the need to make 5x individual thermostats. But it comes down to how much convenience is an issue. With a centralized temperature controller you would have to handle a bunch of wires going all over the place and protect them from melting. 5 Individual arduino controllers and screens would make it simple though. If price isn't an issue you can simply make one and replicate the other 4 identically. As less information is displayed per LCD , 5 small LCDs might be cheaper than a single larger display.

Tradeoffs only you can make.

[edit] Almost forgot the important part: Safety and single point of failure. If through some mishap (wire shorts through melted insulation, or software bug) the central controller locks up all the fryers and grills might stay on. It's probably safer if each grill and fryer is not dependent on failures of the other. So individual solutions might be saver.
By TechMo
#200186
Hi Valen

I'm looking for the most simplistic setup possible - I don't need any fancy displays or such.

What would you suggest I replace the 5 Thermostats with especially since each fryer will be running at a different temperature depending on it's use - e.g. Fries demands a temperature of not more than 170C however breaded chicken works best at around 155c.

Lastly, Safety is paramount importance and each appliance has a main valve, everything else comes after that hence if the main valve is switched off, nothing works. This is also the reason why I want the LCD, it gives me an idea of what the temp is at - of course, I will have to put in place a fail-safe solution in place.

Thanks
By Valen
#200196
I am sorry, I cannot give such suggestions what to buy/replace it with. I have an extremely general mental picture of what your fryer/grill entails as far a hardware goes. I've never done such a project of my own. And I live in another country so advice might not be appropriate for your's.

I suggest you start with prototyping a design for a single appliance. And maybe not even for a food preparation appliance yet. Maybe just for testing heating up a metal block or pan of boiling water with a gas heater. (You know, for controlled safety's sake) Single arduino, single lcd, single temperature sensor appropriate for the job, and whatever means you can control the gas with. Also from a programming perspective you want to keep it simple first with one control variable instead of 5. Then afterwards you have an idea what's needed and what the critical problems are. Once that is working and fleshed out you can consider the next step: expansion to controlling multiple heaters at the same time.
By TechMo
#200202
Hi Valen

That sounds like an idea - let me start procuring the components for 1 device - I'll expand from there on.

Will revert once I have the components required.

Thanks
Mo