Personal computing discussed

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Welch
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I/O of Embedded Computer - Project

Tue Sep 26, 2017 5:08 am

So I've been really surprised that the company that makes the heater for my little house (garage), doesn't have any "smart" functions available. Mostly because it would mean some ultra efficiency in my mind.

I have a Toyostove 730, which is a newer model with digital display of a very popular heater for small houses or cabins here in Alaska. I wish I could controller the temp while away from the house and possibly even a few more "smart" functions that would really save a lot of money due to efficiency.

Just had it open today to clean it out and it got me thinking about how easily accessible everything is. I can imagine a raspberry pi being setup to capture output and then possibly even input requests, remotely. This would mean if I was gone from my house longer than expected, I could keep the heat down or off. On my way home I could set it to something warmer and have it ready to go by the time I arrive home. Way more efficient.

How the heck do you do research on pin outs for circuit boards on a company that apparently isn't popular outside of Alaskan and Japan?
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Re: I/O of Embedded Computer - Project

Tue Sep 26, 2017 5:48 am

If the company does not have a publicly available service manual (and it has not been leaked onto the internet), you pull the board and start identifying components and tracing out the circuits. If the PCB has more than 2 layers (top and bottom) this process will be really "fun".
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Re: I/O of Embedded Computer - Project

Tue Sep 26, 2017 9:17 am

I don't know anything about the specific heater you have but the late 90s gas combi boiler I have at home has an aux input for an external timer/thermostat . This is very basic and just allows the heating to be turned on and off. Assuming your heater has something similar you should be able to get your rasberrypi etc to work a relay that can turn the heater on/off. So whatever system you build for the pi would have to do the timer, thermostat and frost prevention stuff as well as the extra smart stuff that you want to add. You will probably want to disable any of the built in functions in the heater has so the pi can be sure when the heater is on or off (though maybe you'd want to leave the frost prevention stuff alone as a safety measure in case the pi crashes).

First step is tracking down all the manuals you can for your heater.
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Re: I/O of Embedded Computer - Project

Tue Sep 26, 2017 10:05 am

Normally I would encourage such internal tinkering, but I'm willing to bet there are some hardware and software safeties built into the controller somehow.

I'd instead recommend overriding a single existing control, say for example the thermostat slider: http://www.rural-energy.net/images/P-163-3.jpg

This is most likely a slide potentiometer, so perhaps you could replace or supplant it with a digital potentiometer if you were able to find out the resistance range. After wiring the digital potentiometer to the Raspberry Pi you could write a script to digitally control the resistance, making your own thermostat.

My point is to not replace the entire I/O controller. Instead, replace the controls it exposes and make your own physical API into the heater.
 
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Re: I/O of Embedded Computer - Project

Tue Sep 26, 2017 2:40 pm

The display/control board is a separate board that doesn't appear to have any smarts on it. The main circuit board has the micro controller on it. Looking at pictures, there are enough lines in the connectors between the main and display boards that the switches and LEDs are probably passed through as discrete signals. This makes the take over of the control panel the more attractive option, rather than trying to replace the main board and dealing with the high voltage/power interfaces. I'll assume that the functionality you would like can be implemented by manipulating the front panel controls in some fashion and at the correct timing. Then the question is "how far do you want to take this?"

If you want to maintain the front panel controls and functionality as it, then you can build an interposer connects in between the display board and main board. Signals coming from the display board are intercepted by a micro controller on the interposer board. They can then either be passed through or modified according to the new smarts being implemented on the interposer. The interposer board is what feeds actual signals back to the main board.

If you want to replace the entire display board, the your replacement just has to implement the same electrical interface as the old interface board. What you actually for the new interface board doesn't matter after that point. Want to put a touch screen on it? Great. Want to remove it completely and just use WiFi? That works too.

Figuring out the control lines between the display board and mainboard shouldn't be too hard. It looks simple enough that you can probably get away with just a multimeter. Follow the traces from the connectors to the various switches, LEDs, and potentiometers. There aren't enough switches for them to be have to be multiplexed, so that will simplify things. The seven segment displays will be multiplexed, and it's possible they chained the LEDs on to that, effectively making the LEDs on the board look like another one or two seven segment displays.

http://www.ebay.ca/itm/Toyotomi-Toyosto ... Sw~G1ZyUbY

Depending on your programming chops and familiarity this would probably be good place for a Raspberry PI Zero W. Gives you wifi, blue tooth, and a full environment to run in. Pick your language, though Python is an obvious choice here. You could also use something a bit more dedicated, any of the larger Arduinos with a wifi shield would work. But, development would be a bit more invovled. The trade off is that you get much faster startup and don't have to deal with side effects of running a full linux distribution.

--SS
 
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Re: I/O of Embedded Computer - Project

Wed Sep 27, 2017 1:33 pm

I can already see why it isn't popular in the US outside of Alaska: the fuel source.

In any case, is this merely a comfort heater, or is it the sole source of heat? I would be leery of DiY RPi modifications on the only heater standing between an un-winterized space and -50F.
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Welch
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Re: I/O of Embedded Computer - Project

Wed Oct 18, 2017 11:44 pm

Sorry, it's sad but I pretty much forgot I had posted this :|. I've been pretty busy preparing my property for winter and now that I'm done and the white stuff has landed, I should be able to pay more attention to online stuff. MAN, building a house takes so much time :P.

https://www.toyotomiusa.com/factoryOutl ... uct_id=206

This is the unit I have, a 730, the newer version of the Laser 73, which is pretty much the same internally (physical) but the electronics got a big upgrade. Digital readout for the front, more automatic timers and day/week schedule type things and a child lock. I had to clean it out a few weeks ago and the front panel readout and buttons are connected with a simple ribbon cable to the board.

Yes, this is my primary heating source, so I don't plan to do anything with it in the winter. Like you said Ludi... I don't want to battle -50 without a heater. Yeah, the heating oil is just the standard here, unless you get somewhere more south in Alaska where it is warmer and they have natural gas. They recently installed a bunch of gas lines around town and used right away for this, but it's well known nothing is going to be turned on for at least 5 years IF THAT. It's a political goat rope. They wanted to run gas a few 100 miles and then literally stop 40-50 miles outside of our city and truck it the rest of the way. Some politician has a buddy in the trucking industry. It's a good ole' boys club up here still unfortunately.

Yes, SS... you're talking about exactly what I was thinking. The display obviously sends and receives some fairly analog signals to the mainboard. I figured having those signals recieved first by a RPi Zero and then passed on to the display would be perfect. This was all input can still be done manually from the display, but input can also be done from somewhat of a web interface, perhaps eventually building out an app. I don't have an issue with a full Linux distro being on the RPi, especially considering the basic functions I'm talking about. I have thought of some very interesting possibilities for automation if this ends up working out, to include the RPi checking on a google locations from a phone, knowing the time until arrival to get home and turning the heat back up so that it can for instance bring the temp from 55*F to 70*F. So if Google says that it would take 15 minutes to get home and knows that is where I am driving, that it will know to kick on in time for things to heat up by the time I arrive home. Obviously some of these features would be further down the road. Right now I'd love to just have the current set temp and current room temp reported and be able to adjust those remotely.
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SecretSquirrel
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Re: I/O of Embedded Computer - Project

Thu Oct 19, 2017 7:10 am

Two things to consider. The Raspberry Pi doesn't have any analog inputs or outputs. If, by chance, there are thermistors on the control panel, or some other truly analog signal, you will need an something else to sit between the Pi and the control board. It is not terribly likely this is the case, but only exploration will say for sure. The second item is more important. The Pi has 3.3V logic level GPIO and the inputs are not 5V tolerant. When you start looking at signals, pay attention to the voltages used. It's entirely possible that the system uses 3.3V logic but its equally possible that it uses 5V logic levels, or even some other voltage levels. If it's not 3.3V levels (2.4-3.3V for logic high), then you will need some sort of logic level converter.

--SS
 
Welch
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Re: I/O of Embedded Computer - Project

Fri Oct 20, 2017 2:26 am

I'll start looking into the voltages as a first start. If it is a digital display with physical buttons, what are the odds that it is an analog input/output? You are saying we would prefer it to be digital for the sake of easy compatability to the GPIO headers on the RPi?
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Re: I/O of Embedded Computer - Project

Fri Oct 20, 2017 6:43 am

Maybe look at an Arduino then instead if you want analog inputs.
 
SecretSquirrel
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Re: I/O of Embedded Computer - Project

Fri Oct 20, 2017 7:54 am

Welch wrote:
I'll start looking into the voltages as a first start. If it is a digital display with physical buttons, what are the odds that it is an analog input/output? You are saying we would prefer it to be digital for the sake of easy compatability to the GPIO headers on the RPi?


Digital display with physical buttons will be all digital. The only analog thing that might be on the control board would be a temperature sensor. You wouldn't necessarily have to intercept such a signal, though I doubt one exists. You are still going to need some sort of buffer between the RPi GPIO and the control board. It's also quite possible that you will need more signals than exist on the RPi GPIO header. The LED display will be the most complex as it is almost certainly multiplexed. This means that the lines that drive the individual segments are shared between all digits and then one line enables each digit.

Using an Arduino to interpret what is on the display and feed to the RPi over a easier to handle serial interface. The RPi doesn't do high speed digital IO well unless you get into really low level programming.

--SS

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