[cnvogel]

One of the very useful things to own when dealing with embedded computers is a low-voltage/CMOS usb-to-serial cable, such as this one: https://www.adafruit.com/products/954

There are modules that have variable I/O voltage, very handy when dealing with devices that have 1,8V, 2.5V, 3.3V or 5V logic: https://www.sparkfun.com/products/12731

Equipped with such a cable, you can also observe any errors that might occur on bootup, such as when you have made a mistake in configuring your config files on the filesystem.

For normal "Rasperry Pi"-Level work, the cheapest eBay-cable will probably be ok. If you have more exotic devices you'll appreciate UARTs that can produce almost arbitrary baudrates, or might support inverted Tx/Rx pins. I found some chinese knockoffs using a "CH310" UART/i2c/spi chip to be particularly broken.

(EDIT: Added last paragraph, fixed a few typos)

[unwind]

I noticed that the SparkFun product has export restrictions, which seemed funny.

I dug up this text on their site: https://www.sparkfun.com/support#IntExportRestrictions, which says:

[...] These are products designed for civilian use, but that could be used for devious purposes in the wrong hands. [...]

So, I guess that tells me there are weapons or other "dangerous" machines that have UARTs. Who would have thought that, huh? :| Really dubious restriction, but I guess they don't have a choice.

[cnvogel]

You get that for an awful lot of chips or software which are thought to have "dual use" to aid inadequately defined nefarious things.

On most orders for electronics parts, even if it's European distributors shipping to me, in Europe, I'll have to click some boilerplate where I assert to not make the chips available to terrorists on the Denied Persons List of the US department of commerce, which is conveniently available in ASCII...

https://www.bis.doc.gov/dpl/dpl.txt

[cordite]

The same applies when buying microcontroller starter kits, like the MSP430 for school.

That, and clauses about not using it to controller missiles. Which is admittedly more applicable than the weapons of mass destruction (exaggerated) clause in iTunes.

[jone673]

Ah the beauracracy.

[digi_owl]

Do belive the export restriction on encryption is still on the books, just sleeping.

[DanBC]

One of my hard drives "bricked" itself, and I was able to use such a cable to unbrick it.

This SuperUser post talks about it: http://superuser.com/questions/365999/how-do-i-recover-data-...

http://howto.starahead.com/?p=61

http://www.overclock.net/t/457286/seagate-bricked-firmware-d...

https://sites.google.com/site/seagatefix/Home

I had backups, but still, it was nice to be able to do this.

[Laforet]

When I worked in PC repair I used to see one of these every couple of months or so. It feels great to be able to being them back with no loss of data for the customer. I still have the hacked together PL2302 bridge somewhere in my toolbox.