Questions before purchase (A20 LIME2)

Started by andrea76, September 30, 2015, 10:45:28 AM

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andrea76

1) The default power adapter (2A) is sufficient for the olimex a20, a SSD (Crucial MX100) and keyboard/mouse usb connected devices? Or I should buy a more powerful power adapter?

2) I use Debian/Linux distributions. So I can buy the LIME2 version without NAND?

3) The microSD in your shop, how much GB does it have and which class is?

Gerrit

Quote from: andrea76 on September 30, 2015, 10:45:28 AM
1) The default power adapter (2A) is sufficient for the olimex a20, a SSD (Crucial MX100) and keyboard/mouse usb connected devices? Or I should buy a more powerful power adapter?

Do your own math, look at the specs from all the things you mention and add up the currents

Pawel_W

2) You don't need this 4 GB NAND if you don't do embedded solutions, if you do then buy a large (original from Olimex) battery too and make sure that the system gently shuts down when the power gets low, otherwise the data on NAND will get corrupted and the system will not start. System on MicroSD card is much more resilient to power outages.

3) I have Debian Wheezy on NAND and Android on 32 GB cat. 10 microSD card.

MBR

#3
Quote from: andrea76 on September 30, 2015, 10:45:28 AM
3) The microSD in your shop, how much GB does it have and which class is?

You don't have to use the microSD card from Olimex, any microSD card should theoreticaly work. The only difference that the Olimex ones will work surely. And the difference between classes is the writting speed (see https://www.sdcard.org/consumers/speed/), but generally the class 10 cards have also greater reading speed (because High Speed SD bus mode) and faster chips.

Quote from: Pawel_W on September 30, 2015, 11:45:29 PM
2)... otherwise the data on NAND will get corrupted and the system will not start. System on MicroSD card is much more resilient to power outages.

That's right, but if the filesystem on the NAND is mounted readonly, you can power it off anytime with no damage. The downside is that you (obviously) cannot write any changes on it (for compressed filesystems like SquashFS it's even utterly impossible :-) ), so this approach is better suited for an embedded systems (where all writes are redirectet to (overlayed) TmpFS or such) than desktop-like ones.

PS: Beware, journaling systems like Ext3+ write some data back to device even when mounted readonly. But no sane person will use these on the NAND Flash, so there is probably no problem with this ...