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Project Guidance / Re: Possibility to leave the U...
Last post by Dirkhens - Today at 04:03 am
[Solved]
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I did not realize I was such a youngster... being a small fraction of a score younger than most....  still a sexagenarian...
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Installation & Troubleshooting / Re: Content Mismatch
Last post by ENGR1000 - Today at 03:59 am
After trials and research I just purchased another Uno.
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There is a safety concern with using some, not all of these hobby type relay boards, for high current/voltage applications. And the only way you can really be sure of what you're getting, is to have one in hand, and know what you're looking at. And you also need to test it, At 1.5 times the rated current. The relay may stand up to this current, but the question is will the circuit board stand up to it. Does it have enough separation between the circuit traces to be safe. Even a small art between the traces will leave a carbon track. This becomes a resistor, it also becomes a path for electricity to flow. Any carbon track could cause the circuit board to catch fire. Also, the screw terminals on these relays are normally rated between 7A to 8A. To me I would not trust my home or business to this type of relay at high current/voltage. You're better off getting the proper relay/contactor, and driving it with a transistor/2nd relay, At a lower voltage. An SSR, is also a good choice. Just make sure that you use a heatsink and there is plenty of air circulation around it.
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Proyectos / Re: Monitorización sistema ter...
Last post by surbyte - Today at 03:51 am
El proyecto puede resolverse con un MEGA o DUE, yo usaría una TFT que ya trae SD card, asi simplifico tema menú, y dispongo de espacio para presentar información.

Los sensores de presion me parecen bien. Los de temperatura tmb.
Creo que costaría muy poco agregar WIFI al proyecto para estar conectado y hacer el relevamiento via web o usar alguna alternativa Radio Gateway que lo permita. De lo contrario la SD esta bien.

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Project Guidance / Re: Possibility to leave the U...
Last post by Dirkhens - Today at 03:51 am
Fixed it! Thanks! My D- Was flimsy, using a bad cable I took home for testing. In theory running a common wire would work and would need only only more wire and save me 5+! woohoo!
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Project Guidance / Re: Unless button is pressed w...
Last post by Dirkhens - Today at 03:46 am
See the sticky at the top of this forum.
Making newbies dive into the deep is not always the best approach. I know to you and I this is simple, but it's a mindset you need to get into. Telling them their problems are trivial and can be easily solved with generic steps also does not encourage those needing help. Stop being an elitist.
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@westfw thank you, I used the tip you gave me for __ftoa_engine. It was a new concept and I read about in here (http://www.geeksforgeeks.org/extern-c-in-c/). Thank you again, without your guidance I would never learn that.

@krupski, sorry to let you down. I did not mean to. Anyways later if I release the libraries which I am working on right now, I think more people will be benefited if no tweaks are needed on the IDE side. Again I am sorry if I have made you upset.


Things I have done which might be useful for future users:
1) I documented the dtoa_prf function which is the actual function when dtostrf is called. The code does not have any documentation and I think it has been implemented in a very smart and efficient way and without documentation it is hard to understand it.
2) I made a safe version and tried to test it as much as I could in few aspects.
   i) dtosrf and myDtostrf produce the same exact results when size is not an issue. (it was tested for hours by generating random float numbers)
   ii) NAN, INF, -INF are tested with different sizes to make sure correct result is obtained
   iii) size was tested on some variables (I have not seen any suspicious behavior but I think more testing is required which hopefully happens over time when I am testing other parts of the project)
3) finding out that another person has faced the same issue but the whole thread is in german :)


My overall code is in here (well, it was too long so had to attach it)


myDtoa_prf part of this code is exactly same as dtoa_prf and buy reading the comments you can easily understand the original dtoa_prf too.

There is only one part which I did not understand and that is
Code: [Select]
if ((signed char)nDigits < 1)
nDigits = 1;
else if (nDigits > 8)
nDigits = 8;


I tested with
Code: [Select]
if ((signed char)nDigits < 0)
nDigits = 1;
else if (nDigits > 8)
nDigits = 8;


and it produce exact same results after testing with random float number, but I think it is faster because it can be branch if minus. (I am not very familiar with AVR assembly instruction yet but from what I recall from 6800 instruction set, branch if minus was faster than comparing and then branching)
I would be happy if anyone can point out why there is a 1 there instead of 0. I am afraid it is for a very special case and the random number generator has not generated that.

The code I have attached contain the testing section. Let me know if you think the testing part is not accurate, I think it is fairly accurate but just to be sure.


And lastly,
 https://www.mikrocontroller.net/topic/301125
 shows folks who solved the same problem. However my version has one difference. Their version does not print the number at all if it does not fit. My version it prints as much as it can and then set the bool argument which passed by reference to false.



I would like to thank you all for the support, suggestions and your efforts.
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Project Guidance / Re: 64 yr old newby would like...
Last post by TomGeorge - Today at 03:39 am
Hi,
Welcome to the forum.

61 yo here, we are the whippersnappers, so don't feel alone.

Greenhouse is a good project, especially if you do not have a time limit and are prepared to develop it in stages.

Tom.. :)
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