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t3andy
01-08-2013, 12:32 PM
Teensy Diehards - An "universal" USB cable for development.
It's a lot cheaper than buying a separate micro USB adapter.

https://www.sparkfun.com/products/11515
:cool:

MichaelMeissner
01-08-2013, 12:50 PM
I've been thinking about getting that cable. I already have a 2 headed cable (mini/micro) that I got at the local drugstore, since I have both mini and micro devices, but the Uno has the old USB B connector. Fortunately, I still have plenty of B cables from when that was the predominant cable type for attaching printers and external disks.

If you read the comments at sparkfun, you see that multi-headed cables can degrade the signals in some cases. In fact, after writing this post, I was using the combo cable, and the SD card reader had some errors when I was uploading photos. I unplugged the cable, waiting a few seconds, and replugged it back i, and it worked at thos point. So, it might still be useful to have single ended cables. So far, I haven't found a set of USB cable attachments that would have all 5 ends that I need (USB A male, USB A female, USB B male, mini 5 pin male, micro male). Most of the USB travel kits were made before micro became dominant.

PaulStoffregen
01-08-2013, 05:05 PM
I'm a bit skeptical about that cable. It appears to be just 3 cables spliced (no selector switch routing the signals to only 1 location), which is almost certain to cause signal reflections.

Notice they say:



You may run into issues when transferring large amounts of data (hard drives, flash drives, etc), so it's best to just use it for low-speed applications like microcontrollers or charging devices.


It probably works fine at 1.5 and 12 Mbit/sec speeds. But even at 12 Mbit/sec, with 2 long stubs hanging off what is supposed to be point-to-point transmission line, the signal quality will be lower than it should be. Buyer beware.



Edit: the comments are filled with discussion of the signal quality issues and numerous reports it does not work with certain devices. If you buy this and it doesn't work with a Teensy board, probably best to return it to Sparkfun.

t3andy
01-08-2013, 05:43 PM
Buyer beware.

I will try anything for $5.95. It cost me $10 for a mini to micro converter adapter. <--- that is ~1/2 cost of the Teensy 3!
It would be nice if pjrc.com would carry an inexpensive adapter when customers buy the Teensy 3?

MichaelMeissner
01-08-2013, 11:47 PM
I will try anything for $5.95. It cost me $10 for a mini to micro converter adapter. <--- that is ~1/2 cost of the Teensy 3!
It would be nice if pjrc.com would carry an inexpensive adapter when customers buy the Teensy 3?
Well given the European Union has specified a common charger, which is the micro USB cable (except of course Apple decided to go its own way), just about any newly designed device these days will use the cable.

I just recently bought some short micro USB cables from ebay from US sellers (lets see two retractable cables for under $4, two 18cm cables also under $4, and a wall wart/car charger combination that each charge 2 devices with cables for $11) all with 'free' shipping. So, you can get the cheap cables at various places (or if you have upgraded your cell phone or have electronic book readers/tablets, you likely already have the cables).

MichaelMeissner
01-09-2013, 04:57 AM
I should mention, the cable that I really had to search for recently was a double ended cable with the A plug on both ends, for a breadboard power supply that I could power two sets of rails at the same or different power levels (3.3, 5, or none volts). I have older devices that use the square-ish B plug (but the Uno surprised me by being fairly new with this relic), quite a few devices that use the 5 pin mini plug (that is rapidly disappearing), as I mentioned newer devices seem to have the micro cable, I have several electronic universal chargers that do various voltages with several different plugs like the 2.1mm barrel plug also used by the Uno, but the breadboard power supply was the first device that used the A plug that you normally plug into the computer or wall wort so you needed an A end on both sides.

I dislike companies that seem to design a new cable for every new product, particularly when they upgrade a product and switch cables to yet another non-standard cable.

t3andy
01-29-2013, 01:35 AM
Just got the SF cable in and so far it works fine. Only time will tell.;)

MichaelMeissner
01-30-2013, 02:02 AM
As I said, I have a cable with 2 ends (mini/micro). It works maybe 95% of the time, but I have had times when it did not work. So now, I tend to use it mostly for charging batteries. Hopefully yours will work flawlessly.

t3andy
02-10-2013, 07:40 PM
@Paul S

It probably works fine at 1.5 and 12 Mbit/sec speeds. But even at 12 Mbit/sec, with 2 long stubs hanging off what is supposed to be
point-to-point transmission line, the signal quality will be lower than it should be. Buyer beware.

So far, after one week, this cable seems to perform just fine.

Really, who cares about "degraded" signal quality unless the bootloader does NOT perform CRC or checksum and data verification of the data being upload to the Teensy 3. I hope this is not the case?

PaulStoffregen
02-10-2013, 10:20 PM
The USB protocol performs CRC checks on every packet. There are also redundant bits in the tokens and other measures in the USB protocol to detect errors at the lower levels. Teensy does not add more checks. If there are errors, the loading could be slower as the protocol retries some packets, or it could fail if there are too many errors. Teensy Loader will show "Download Failed" in red if transmission fails, and of course the board will not automatically boot to the failed code. The USB protocol is actually very good at detecting errors.

Just because the protocol can detect errors does not necessarily mean the operating system on your computer can report them to you. In fact, all 3 do a pretty terrible job in most causes (eg, after you've loaded code onto Teensy). Microsoft is particularly bad, where errors during device enumeration cause an on-screen message which advises you to install a new driver, rather than any indication of signal quality issues being the real cause! Microsoft's CDC serial COM port driver is also very poor, in some cases where it loses communication, it can leave a corrupted registry entry that causes it to fail the next time it sees the device. Teensy has a special delay before rebooting, to avoid Windows bugs! It's really sad the state of USB drivers is so terrible, but it's not so surprising. USB has very conservative specs, which is why funky cables like this can work. But because USB has always been so extremely reliable, none of the operating systems have developed particularly robust drivers to deal with the problems which almost never happen.

I'm glad it's working for you. If you do have strange problems, obviously try a standard cable before anything else.

Legb
02-17-2013, 11:06 AM
The SF cable was on my list to try, however, looking on ebay I found sellers offering Mini B and Micro B Blackberry cables at under a pound each and at 12" length they were perfect for keeping multiple devices connected and at least the USB cables were tidy :)

I then looked for a powered USB hub with individual power switches for each port, the 7 port USB 2.0 hub was around 5.

I'm much happier unplugging USB A plugs than the mini or micro connectors, and at the price the whole solution of cables and hub cost being around 12 all in, I can easily reset a board not responding to the reset button with an on/off switch, rather than unplugging USB cables and risking damage to connectors.

And everything is sitting on one switch ready just to be powered up and worked on without looking for a spare port and then cables. Of course, the discipline to use this hub ONLY for development is worth it in the long run, avoiding the temptation to quickly connect a USB key is the biggest hurdle, keeping all ports occupied makes it not so convenient.

t3andy
02-22-2013, 08:16 PM
And for $4 USD you can buy this from Adafruit
http://www.adafruit.com/products/1197

MichaelMeissner
02-22-2013, 10:33 PM
And for $4 USD you can buy this from Adafruit
http://www.adafruit.com/products/1197

Well $4 + shipping (my last Adafruit purchase was around $3.75 for shipping via US post office to USA delivery).

Note, the Sparkfun cable has 3 ends (B male which would be useful in an Adruino Uno, mini B male which would be useful in a Teensy 2.0/2.0++, and micro B male which is useful for a Teensy 3.0). If you have a mixture of devices, it can be useful to only have one cable.

BTW, I do wish the USB folk had chosen different letters for the 4 pin mini B connector, the 5 pin mini B connector, and the 4 pin micro B connector to make it easier to search for the right cable.

MichaelMeissner
02-22-2013, 10:48 PM
And for $4 USD you can buy this from Adafruit
http://www.adafruit.com/products/1197

Well $4 + shipping (my last Adafruit purchase was around $3.75 for shipping via US post office to USA delivery).

Note, the Sparkfun cable has 3 ends (B male which would be useful in an Adruino Uno, mini B male which would be useful in a Teensy 2.0/2.0++, and micro B male which is useful for a Teensy 3.0). If you have a mixture of devices, it can be useful to only have one cable.

BTW, I do wish the USB folk had chosen different letters for the 4 pin mini B connector, the 5 pin mini B connector, and the 4 pin micro B connector to make it easier to search for the right cable.

linuxgeek
02-22-2013, 11:42 PM
I just picked up 2 micro USB cables at Fry's for $1.99/each.

http://www.frys.com/product/7214583?site=sr:SEARCH:MAIN_RSLT_PG

Paul, maybe you could buy their stock and sell them along with your T3. :)