rownyr
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Lower temperature support

Wed Jul 11, 2012 1:39 am

If possible, please include industrial LAN9512i chip instead of commercial LAN9512. The former has lower temperature support (-40°C to 85°C). The "AP" mentioned in FAQ has the same low temperature range so the whole board should be usable down to -40 Celsius.

obarthelemy
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Re: Lower temperature support

Wed Jul 11, 2012 2:02 am

Sorry, this would not fit the design goals.

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Re: Lower temperature support

Wed Jul 11, 2012 2:16 am

Why? Cost?

jamesh
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Re: Lower temperature support

Wed Jul 11, 2012 2:49 am

I don't know the cost difference, but if they found it necessary to make two models I'm sure there is one. Assuming they are pin and software compatible, you could remove one from the board yourself and replace with the higher spec one. Not an easy job though.

Main issue would be - why does a device designed to be used in teaching computing need to run at -40. Not many classrooms are used when they gets that cold!
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holmez
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Re: Lower temperature support

Wed Jul 11, 2012 6:30 am

Perhaps rownyr is considering the governments educational cost cutting.

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Re: Lower temperature support

Wed Jul 11, 2012 6:48 am

holmez wrote:Perhaps rownyr is considering the governments educational cost cutting.
Ouch! :D
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Re: Lower temperature support

Wed Jul 11, 2012 6:52 am

jamesh wrote:
holmez wrote:Perhaps rownyr is considering the governments educational cost cutting.
Ouch! :D
Shouldn't that be "Brrrr!"?

rownyr
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Re: Lower temperature support

Wed Jul 11, 2012 10:06 am

holmez wrote:Perhaps rownyr is considering the governments educational cost cutting.
LOL! Actually, I was thinking about using RPi in a CarPC in the winter :)

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Re: Lower temperature support

Wed Jul 11, 2012 11:13 am

In which country? UK you should be OK with the standard device I would think - in a box there should be some heat build up to survive any UK winter.
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AndrewS
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Re: Lower temperature support

Wed Jul 11, 2012 11:47 am

...or instead of buying a ModelB and trying to remove the existing USB chip (probably quite difficult, due to the large solder-area under the chip), I guess you could wait for the ModelA, and 'mod' it into a ModelB with the lower-temperature USB chip you want (and associated SMD resistors) using the schematics http://elinux.org/RPi_Hardware#Schematic_.2F_Layout as a guide :geek:

rownyr
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Re: Lower temperature support

Wed Jul 11, 2012 12:04 pm

Thank you for all suggestions.
jamesh wrote:In which country? UK you should be OK with the standard device I would think - in a box there should be some heat build up to survive any UK winter.
Unfortunately it's not UK, it's Poland, where -20°C is normal and I doubt the build up heat would last long. So, I have three options:

- manually change chip to "i" version, or solder it to ModelA
- somehow heat the chip before running the board
- do not use RPi

I hope there are some solutions for option number 2 :D

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AndrewS
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Re: Lower temperature support

Wed Jul 11, 2012 9:36 pm

Could you mount the CarPC in the passenger compartment (e.g. under a seat or something) and only switch it on after it's warmed up? Or are you planning to leave it switched on (e.g. overnight) when you're not in the car yourself?

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Re: Lower temperature support

Wed Jul 11, 2012 10:21 pm

The LAN chip generates a fair bit of heat, so I think you'll have no problem once it's started.
You may find it just fails to work for a few minutes initially. (Or more likely just works.)

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Re: Lower temperature support

Thu Jul 12, 2012 1:11 am

jamesh wrote: Main issue would be - why does a device designed to be used in teaching computing need to run at -40. Not many classrooms are used when they gets that cold!
What? Do you expect that educational students will only use these as stand-alone computers? No way, students and adventuresome teachers will mod them and push them to their limits! Just look at the Pongsat project - students have been sending things to the edge of space! A low temp chip is almost a student necessity!

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Re: Lower temperature support

Thu Jul 12, 2012 2:12 am

Alligator wrote:
jamesh wrote: Main issue would be - why does a device designed to be used in teaching computing need to run at -40. Not many classrooms are used when they gets that cold!
What? Do you expect that educational students will only use these as stand-alone computers? No way, students and adventuresome teachers will mod them and push them to their limits! Just look at the Pongsat project - students have been sending things to the edge of space! A low temp chip is almost a student necessity!
Necessary for about 1000 people out of 1Million? Not all students are adventurers!
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NeilM
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Re: Lower temperature support

Thu Jul 12, 2012 2:21 am

jamesh wrote:
Alligator wrote:
jamesh wrote: Main issue would be - why does a device designed to be used in teaching computing need to run at -40. Not many classrooms are used when they gets that cold!
What? Do you expect that educational students will only use these as stand-alone computers? No way, students and adventuresome teachers will mod them and push them to their limits! Just look at the Pongsat project - students have been sending things to the edge of space! A low temp chip is almost a student necessity!
Necessary for about 1000 people out of 1Million? Not all students are adventurers!
Erm, that's 0.1%, quite significant in some circles...

Neil.

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AndrewS
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Re: Lower temperature support

Thu Jul 12, 2012 8:59 am

If there's really such a demand, I'm sure some enterprising user will come up with a "FreezerPi" low-temperature Pi-modding service ;)

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Re: Lower temperature support

Thu Jul 12, 2012 11:09 am

NeilM wrote:
Erm, that's 0.1%, quite significant in some circles...

Neil.
But not in mine. Or the Foundation who really don't want to put on a more expensive chip for 0.1% of the user base. It's the same reason MPEG2 isn't there. Why should 99.9% of the user base pay for a feature on 0.1% want?

On the other hand, if you are looking for some dodgy boson somewhere, 0.1% would be quite large.
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0117blocky
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Re: Lower temperature support

Thu Jul 12, 2012 12:09 pm

This thread has got a bit silly, so I'm going to add to it.
People put playstations in cars which are designed to operate at normal room temperatures the only time they remove them is to stop them being stolen and not frozen.
Slightly more serious note. The component I would worry the most on RPi is the SD card holder
which is flimsy and at extreme low temperatures the plastic will be quite brittle. The SD card holder could be prone to cracking from the pressure of the SD card.

Changing a chip or two does not make an electronic system cold weather proof.
Expensive component and completed board testing does.

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reiuyi
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Re: Lower temperature support

Sat Jul 14, 2012 3:53 pm

0117blocky wrote: Changing a chip or two does not make an electronic system cold weather proof.
Expensive component and completed board testing does.
Besides, it's just what the datasheet says

I'm sure the LAN9512 IO chip works fine at lower temperatures. And if it doesn't.. well, it only takes like 10 seconds before it's heated up itself, then it'll start up anyway.

I mean what do you think is the difference between the LAN9512 and the LAN9512i? I personally think it's just the plastic casing that is more rugged and less prone to brittleness in the industrial version. There shouldn't be any difference in the die nor the metal pins. I've never seen electrical components fail due to cold environments. I once actually did freezer tests on several of my own creations and they all survived -30°C without further consequences. Surely a raspberry pi won't survive 50 years in windy and snowy Arctic conditions, but it'll be fine inside the protection of a car.

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